THE EDWARD AND MARY ALLEN LECTURE IN STRUCTURAL DESIGN: HARNESSING EXTRAORDINARY MECHANICS FOR STRUCTURAL DESIGN

Master builders throughout history have made significant strides in exploiting forms to enclose three‐ dimensional spaces, to provide shelter or to bridge two‐dimensional voids, such as water and roadways. In absence of numerical prediction methods, they resorted to trial and error construction practices or structural theory to establish a good enough structural form. Pier Luigi Nervi, structural engineer and designer of the exquisite Little Sports Palace (Rome, Italy, 1958), stated: ‘Resistance due to form, although the most efficient and the most common type of resistance to be found in nature, has not yet built in our minds those subconscious intuitions which are the basis for our structural schemes and realizations’ [1]. I place my scholarship in this force‐modeled form tradition and focus on the advancement of analytical and computational approaches to predict and design the overall properties, stability, and failure of structural surfaces. In particular, I am interested in shells, membranes, and rod networks because they exhibit fascinating mechanical behaviors. I will talk about how we discovered, studied, designed and built surfaces that efficiently carry extreme loading, self-lock, adjust their stiffnesses, morph shape, or amplify motion. We have used these extraordinary mechanics to innovate systems ranging from macro-scale adaptive shading devices to medium-scale robotically constructed waste-free vaults and large-scale storm surge barriers.

[1] P. Nervi, Costruire Correttamente, Milan: Ulrico Hoepli, 1955.

FPO: OLEK PRESENTS HIS DOCTORAL WORK !

On Friday 9/23/, Olek (Alexander) Niewiarowski defends his work on “Towards a conic programming implementation of tension field theory for the static analysis of pneumatic membrane structures” at 11am in Friend 006.

POST-DOC POSITION AVAILABLE

The Form Finding Lab in the Department of Civil and Environmental Engineering (CEE) at Princeton University invites applications for a post-doctoral or more senior research position to support research on the robotic construction of discrete element systems. The research will be conducted under the direction of Professor Sigrid Adriaenssens.

Responsibilities will include:

  • Developing a computational framework that generates element geometries loaded under internal membrane or axial action, and tessellation of efficient element layouts; and that integrates robotic construction approaches;
  • Overseeing day-to-day graduate and possibly undergraduate and high school student’s research as it relates to project goals and meeting project milestones and go/no-go points;
  • Giving and contributing to research seminars within the Department of Civil and Environmental Engineering;
  • Presenting at conferences and leading journal publication efforts;
  • Leading outreach effort of designing and constructing demonstrators, and developing and writing research proposals.

Minimum qualifications:

  • Doctoral degree in mechanical or civil engineering, architectural engineering, physics or applied mathematics field;
  • Appropriate experience in form finding and optimization methods, discrete element modeling and prototyping;
  • Strong project management skills and a very good publication record.

This is a 1-year position and preferred start will be in January 2022 or earlier. Interested candidates should submit an application online at https://www.princeton.edu/acad-positions/position/21961.

AWARD: POINEERS’AWARD

I am humbled to have received the Pioneers’ Award today amongst such prominent engineers. It has been a tradition of the Spatial Structures Research Centre of the University of Surrey, to recognise and honour those who have made significant contributions in the field of spatial structures.

AWARD: Architect’s Magazine R+D Award

The LightVault won the 2021 Architect’s Magazine R+D Award. This is what Juror Jane Grant said “The success of the installation shows the impact that robotic solutions can have on the construction industry—they’re not just stacking vertical walls, but also creating complex shapes.”

FUNDING: NSF – CMMI WASTE-FREE ROBOTIC CONSTRUCTION OF SPATIAL DISCRETE ELEMENT STRUCTURES

The construction industry is one of most resource‐intensive sectors and yet much civil infrastructure continues to be constructed with traditional waste-intensive approaches. However robotic added manufacturing is projected to significantly disrupt the construction industry in the next decades. Its advantages include productivity gains, reduced labor costs, safer working environments and one-off, complex building designs that are not technically and economically feasible at present. Current building forms, constructed with robots, have significant economic and environmental consequences due to their construction process, which is still deeply rooted in a pre-robotic construction rationale. During construction, these forms need form and shore work, which goes to waste once the entire structure is completed. The research will develop computational and physical approaches for the analysis, construction-focused design, and robotic assembly of long span discrete structures, to build without any form or shore work waste. Additionally, this project will enhance research experiences for high school, undergraduate and graduate  students as well as a postdoctoral researcher, and will provide outreach to the K-12 minority community through an annual conference and an institutional summer materials research academy.

HONOR: VICE PRESIDENT INTERNATIONAL ASSOCIATION OF SHELL AND SPATIAL STRUCTURES

I am humbled to have been elected as vice president to the International Association of Shell and Spatial Structures. This international Associations bring together researchers and practitioners working in the areas of lightweight structures and has included many prominent and inspirational structural designers and artists under its members including Felix Candela, Heinz Isler and Bill Baker. I look forward to advancing this Association in the next 3 years.

JOURNAL PUBLICATION: Mapped phase field method for brittle fracture

Phase field method has proven capable of producing complex crack patterns in solids. It introduces a continuous phase field to regularize the sharp crack discontinuities. However, the applicability of this method to engineering problems is hindered by its computational costs. In this work, we proposed a mapped phase field method as a possible route to resolve this issue. The core of this method is a map that connects the physical domain to a parametric domain, which is essentially a local re-parametrization of the physical domain where large gradients are expected. By the use of this map the strongly varying fields can be approximated by a much smoother function. The reparametrized solution is solved via standard finite element in the parametric domain and then mapped back to the physical domain. A simple analysis shows that, with a properly defined map, such method consumes much less computational resources compared with conventional phase field method, without loss in accuracy. The map can also be easily manipulated to adapt to the evolution of cracks, and thus providing a flexible framework to simulate complex crack patterns without any knowledge of the crack path in advance. The advantages of our proposed method are further shown by four different numerical examples: single edge crack under symmetric and anti-symmetric loading, three-point bending, and L-shape panel under cyclic loading. The article can be freely downloaded here .

AWARD: Structural Engineers Association of Illinois: Best Special Structure for the LightVault

Displayed at the heart of SOM’s exhibition “Anatomy of Structure: The Future of Art and Architecture” in London, the Robotic Construction of the Glass Vault was assembled live onsite by robots through the course of the exhibition. The interactive installation required an intricate collaboration between SOM and Princeton University CREATE Lab and Form Finding Lab, with assistance from the TU Delft Glass & Transparency Research Group. The robotic arms were provided by Global Robots and the glass bricks were provided by Poesia Glass Studio. Structural Engineers Association of Illinois (SEAOI) honored the installation as a winner in the Best Special Structures category.

SEAOI’s Excellence in Structural Engineering Awards competition takes place every year recognizing innovative achievements in structural engineering.

Learn More

JOURNAL PUBLICATION: ILLUSTRATING MEMBRANE-DOMINATED REGIMES IN PRESSURIZED THIN SHELLS

Pressurized thin-wall structures cover a broad range of applications, including storage tanks, pressurized rubber flood barriers, and large span enclosures. To accurately model such structures, the analyst must select the appropriate mechanical formulation (e.g. membrane vs shell). Membranes are assumed to have negligible bending stiffness and respond to compression by wrinkling; shells resist axial compression (before buckling) and bending efficiently. While theoretical research on these differences is vast, this study aims to explicitly clarify the consequences of this choice and permit a comparison of error between membrane and shell formulations. Therefore, this paper presents a parametric study of canonical pressurized thin-wall structural geometries (i.e. semi-cylinder, hemisphere) to illustrate the transitions between membrane and bending dominant behavior. The mathematical models of a pneumatic 5-parameter shell and membrane are presented and employed to quantify the effects of variables such as thickness and geometry on the amount of membrane, bending, and shear energy. The effects of inflation pressure, self-weight, and hydrostatic loads are also considered. The graphical results, presented in terms of dimensionless quantities in the design space, are general and should be of interest to the theorist and practitioner alike.

AWARD: MATTHIAS RIPPMANN PRIZE

For my “continuous scholarship and innovation at the intersection of architecture and structural design” I have been awarded the 2020 Matthias Rippman Prize, granted by DigitalFUTURES (Tongji University). I am grateful for this recognition of our work!

JOURNAL PUBLICATION: Three cooperative robotic fabrication methods for the scaffold-free construction of a masonry arch

Geometrically complex masonry structures (e.g., arches, domes, vaults) are traditionally built with scaffolding or
falsework to provide stability during construction. The process of building such structures can potentially be
improved through the use of multiple robots working together in a cooperative assembly framework. Here a
robot is envisioned as both a placement and external support agent during fabrication – the unfinished structure
is supported in such a way that scaffolding is not required. The goal of this paper is to present and validate the
efficacy of three cooperative fabrication approaches using two or three robots, for the scaffold-free construction
of a stable masonry arch from which a medium-span vault is built. A simplified numerical method to represent a masonry structure is first presented and validated to analyze systems composed of discrete volumetric elements.

This method is then used to evaluate the effect of the three cooperative robotic fabrication strategies on the
stability performance of the central arch. The sequential method and cantilever method, which utilize two robotic
arms, are shown to be viable methods, but have challenges related to scalability and robustness. By adding a
third robotic agent, it becomes possible to determine a structurally optimal fabrication sequence through a multi objective optimization process. The optimized three robot method is shown to significantly improve the structural
behavior over all fabrication steps. The modeling approaches presented in this paper are broadly formulated and
widely applicable for the analysis of cooperative robotic fabrication sequences for the construction of masonry
structures across scales.

CHAPTER PUBLICATION: Shell structures for large span roofs

When we hold a sheet of paper, it cannot support its own weight and flops down . However, if we curve it, the same sheet is stiff and can actually now also hold a number of paperclips. Shells, like Toyo Ito’s Meiso no Mori canopy, act in the same way.

S. Adriaenssens, ‘Leichte Konstruktionen für weitspannende Dächer, in Atlas Tragwerke (Manual of Structural Design), 1st ed. DETAIL Engineering, 2021

GRADUATION: CONGRATS CLASS OF 2021 AND IN PARTICULAR JESSICA FLORES!

It has been a challenging year in so many ways and yet the class of 2021 has risen up to all these challenges. Congrats to this resilient and great class! In particular to my advisee, Jessica Flores for obtaining her Master of Science in Engineering. Jessica has pushed the limits of what we know about the mechanics of curved crease origami! Ave et Vale!

JOURNAL PUBLICATION: A new finite element level set reinitialization method based on the shifted boundary method

We propose an efficient method to reinitialize a level set function to a signed distance function by solving an elliptic problem using the finite element method. The original zero level set interface is preserved by means of applying modified boundary conditions to a surrogate/approximate interface weakly with a penalty method. Narrow band technique is adopted to reinforce the robustness of the proposed method where a smooth initial guess for the nonlinear equation is given by solving a Laplace’s equation. Numerical benchmarks in both two dimensions and three dimensions confirm the optimal convergence rates under several different error measures including an interface error measure, showing that our method is accurate and robust. A three-dimensional genus 2 surface is adopted to demonstrate the capability of the method for the reinitialization of complicated geometries.

JOURNAL PUBLICATION: Numerical modeling of static equilibria and bifurcations in bigons and bigon rings

In this study, we explore the mechanics of a bigon and a bigon ring from a combination of experiments and numerical simulations. A bigon is a simple elastic network consisting of two initially straight strips that are deformed to intersect with each other through a fixed intersection angle at each end. A bigon ring is a novel multistable structure composed of a series of bigons arranged to form a loop. We find that a bigon ring usually contains several families of stable states and one of them is a multiply-covered loop, which is similar to the folding behavior of a bandsaw blade. To model bigons and bigon rings, we propose a numerical framework combining several existing techniques to study mechanics of elastic networks consisting of thin strips. Each strip is modeled as a Kirchhoff rod, and the entire strip network is formulated as a two-point boundary value problem (BVP) that can be solved by a general-purpose BVP solver. Together with numerical continuation, we apply the numerical framework to study static equilibria and bifurcations of the bigons and bigon rings. Both numerical and experimental results show that the intersection angle and the aspect ratio of the strip’s cross section contribute to the bistability of a bigon and the multistability of a bigon ring; the latter also depends on the number of bigon cells in the ring. The numerical results further reveal interesting connections among various stable states in a bigon ring. Our numerical framework can be applied to general elastic rod networks that may contain flexible joints, naturally curved strips of different lengths, etc. The folding and multistable behaviors of a bigon ring may inspire the design of novel deployable and morphable structures.

OPINION: WHY CIVIL ENGINEERINGS STUDENTS SHOULD MAKE THINGS

In the American Society of Civil Engineer’s Member Voices article, Joe Scanlan (prof. Visual Arts at Princeton University) and I discuss the value of haptic learning for civil engineering students; why learning and working with their hands makes them better civil engineers.

REVIEW: Large-scale origami locks into place under pressure

In engineering, a deployable structure is one that can change shape in a way that greatly alters its size — large-scale examples include scissor lifts and bouncy castles. Conventional deployable structures are transformed into a larger shape through the extension of linkages (as in scissor lifts) or by inflation (bouncy castles). Both types of structure are then secured into their new shape by an external agent: a lock and the sustained application of air pressure, respectively. However, neither can secure themselves. This new approach I write about, does just that.

PANEL: MATERIALS, BRIDGING ARTS AND ENGINEERING

Materials are important DNA of culture: they shape how a society functions, how it looks, and how it feels. New materials enable new ways of living. In this panel we explore this relationship and also wonder how our human sensuality and culture influence which new materials are successful. https://materials.psb-prod.princeton.edu/events/symposium-2021

image: SU Beningfeld

PRESENTATION: Structural Forms in Architecture

By 2050, 70% of the world’s population will live in cities. We envision, design and construct structures that those city dwellers depend on daily. The construction industry is one of most resource‐intensive sectors, and yet our urban infrastructure continues to be built in the massive tradition in which strength is pursued through material mass. In contrast, I have focused my research on structural systems that derive their performance from their curved shape, dictated by the flow of forces. As a result, these structures can be extremely thin, cost‐effective, and have a smaller carbon footprint. My core research question is  ‘What is the relationship between form and efficiency in structures?’ In my lecture, I will focus on the design, optimization and realisation of structural forms for long-span shells, large-scale raised and submerged flexible net barriers, and adaptive building facades.  Some of these systems are inspired by systems that have evolved in biology, art or craft.

PRESENTATION: TENSION-ONLY STRUCTURES – FEELING A LITTLE STRETCHED

I am delighted to present our research on tension-only structures to architecture and engineering students in Prof. Ochsendorf’s Structures course at MIT. Our advances on the mechanics of suspended rope bridges, inflateable sea barriers and hanging networks will be discussed.

International Day of Women and Girls in Science

According to the UNESCO Institute for Statistics, women make up less than 30% of the world’s researchers. Today, Thursday 11th February 2021, is the International Day of Women and Girls in Science. A big shout out to all the women and girls changing the world through science!

HONOR: ASCE SEI FELLOW

It is with great joy that I can inform you that I have been named Fellow of the Structural Engineering Institute (SEI) of ASCE (American Society of Civil Engineering). The SEI Fellow grade distinguishes members of ASCE as leaders and mentors in the profession. I am being recognized for “her seminal contributions to the understanding of the mechanics of large-scale shells and membranes through the development of methods for form-finding, analysis and optimization, and for her leadership in bridging art and engineering to bring innovative solutions to the 21st century challenges of the built environment.” My thanks go out to all my students, collaborators, colleagues and all the other people (you know I mean you) that make my work possible every day!

EXHIBITION: Lace -HARNESSING LARGE DEFORMATIONS IN INTERLACED ELASTIC NETWORKS

How can art inspire engineering systems? We have been working with bobbin lace and textile artists to find out. Our work is exhibited at the 2021 Joint Mathematics Meetings. Inspired by a traditional bobbin lace pattern, ‘torchon ground’, elastic strips are interlaced to create a gradient of out-of-plane behavior. The key structural element is a bigon which consists of two strips deformed so as to intersect each other at a fixed angle at each end. Numerical modeling of each strip as a Kirchhoff rod shows that the 3D shape of a bigon depends on the width-to-thickness ratio of the component strips and the angle between strips. In this sculpture, the strip width and thickness are constant and the angle is varied along one axis. Intersecting twisted pairs in this torchon ground pattern form curved polygon cells with non-vanishing and tunable Gaussian curvature through the coupling of geometry and elasticity

PRESENTATION: DigitalFUTURES- Shell Structures

To start off the year in a good spirit, I cordially invite you to Virtual Panel and Lecture on Shell Structures on January 16th 2021 (9AM EST, 3PM CET, 10PM China) hosted by Philip Yuan on the DigitalFUTURES platform.  Besides myself, Philippe Block (https://www.block.arch.ethz.ch/) and Chris Williams (http://www.archeng.se/about/people/chris-williams/) will be offering thoughts and design approaches to shells.  This event explores a new way of connecting.

As the date comes closer, I will provide you with more details.

And now we welcome the new year, full of things that have never been.

And now we welcome the new year, full of things that have never been. – Rainer Maria Rilke (1875-1926)

Our best wishes to you from us at the Form Finding Lab.

JOURNAL PUBLICATION: Human–robot collaboration: a fabrication framework for the sequential design and construction of unplanned spatial structures

Robots in traditional fabrication applications act as passive participants in the process of creation—simply performing a set of predetermined actions to materialize a completed design. We propose a novel bottom-up design
framework in which robots are instead given the opportunity to participate centrally within a creative design process. This paper describes how two 6-axis industrial robotic arms were used to cooperatively aggregate a collection of solid spherical units. The branching spatial structure being constructed is unplanned at the outset of this process, and is instead designed in pseudo-real time during construction. This ‘design-as-you-build approach relies on robotic input, in the form of path-planning constraints in tandem with human evaluation and decision-making. The resulting structure emerges from a human–robot design collaboration operating within the specified physical domain.

Free downloads here for the first 50 downloads.

JOURNAL PUBLICATION: Robotic vault: a cooperative robotic assembly method for brick vault construction

Geometrically complex masonry structures built with traditional techniques typically require either temporary scaffolding or skilled masons. This paper presents a novel fabrication process for the assembly of full-scale masonry vaults without the use of falsework. The fabrication method is based on a cooperative assembly approach in which two robots alternate between placement and support to first build a stable central arch. Subsequently, the construction is continued individually by the robots – building out from the central arch based on an interlocking diagonal brick sequence. This proposed method is validated through its successful implementation in a full-scale vault structure consisting of 256 glass and concrete standardized bricks. The paper includes strategies for developing the design, sequencing, and robotic assembly methods used to build the vault.

POST DOC RESEARCH POSITION: ORIGAMI MECHANICS

The Form Finding Lab in the Department of Civil and Environmental Engineering (CEE) at Princeton University invites applications for post-doctoral and more senior research position to support research on the mechanics of curved crease origami. The research will be conducted under the direction of Professor Sigrid Adriaenssens. Responsibilities include conducting experimental and computational mechanics research as it relates to developing novel curved crease origami systems; overseeing day-to-day graduate and possibly undergraduate student research as it relates to project goals and meeting project milestones and go/no-go points; organizing and leading a curved crease origami workshop with our collaborating origami artist and mathematicians and designers; presenting at conferences and leading journal publication efforts; leading outreach effort of designing and constructing demonstrators; developing and writing research proposals. This is a 1-year position. Minimum qualifications: doctoral degree in mechanical or civil engineering, physics or applied mathematics field, appropriate experience in computational mechanics and mechanics of slender systems, prototyping and artistic flair. Strong project management skills and a superior publication record. Interested candidates should submit an application online at https://www.princeton.edu/acad-positions/position/18321

Applications should include a CV, a brief statement of research experience and interests, and the contact information for three references. Please send inquiries to sadriaen@princeton.edu. This position is subject to the University’s background check policy. Princeton University is an Equal Opportunity/Affirmative Action Employer and all qualified applicants will receive consideration for employment without regard to age, race, color, religion, sex, sexual orientation, gender identity or expression, national origin, disability status, protected veteran status, or any other characteristic protected by law.

GUEST SPEAKER: Rethinking Concrete, rethinking material conventions in the Anthropocene

Rethinking Concrete: Material Conventions in the Anthropocene, an interdisciplinary conference organized by Forrest Meggers and Lucia Allais, will discuss new approaches to the lifespan, material dynamics, cultural history, and design potential of reinforced concrete. Once conceived as a quintessentially modernist material, a “liquid stone” that announced the arrival of an eternal present, reinforced concrete is in fact a highly dynamic technological system, subject to inevitable failure through carbonation and other processes. Speakers will problematize the material conventions embedded in reinforced concrete, and expose its role as a complex agent of the anthropocene.

Conversations and presentations among speakers from architecture, engineering, material science, conservation, and design will include Daniel Abramson, Sigrid Adriaenssens, Ueli Angst, Dorit Aviv, Philippe Block, Brandon Clifford, Aude-Line Dulière, Branko Glisic, Tsz Yan Ng, John Ochsendorf, Evan Oskierko-Jeznacki, Antoine Picon, Sarah Nichols, Elisabeth Marie-Victoire, and Claire White, among others.

JOURNAL PUBLICATION: Machine learning generative models for automatic design of multi-material 3D printed composite solids

Mechanical metamaterials are artificial structures that exhibit unusual mechanical properties at the macroscopic level due to architected geometric design at the microscopic level. With rapid advancement of multi-material 3D printing techniques, it is possible to design mechanical metamaterials by varying spatial distributions of different base materials within a representative volume element (RVE), which is then periodically arranged into a lattice structure. The design problem is challenging however, considering the wide design space of potentially infinitely many configurations of multi-material RVEs. We propose an optimization framework that automates the design flow. We adopt variational autoencoder (VAE), a machine learning generative model to learn a latent, reduced representation of a given RVE configuration. The reduced design space allows to perform Bayesian optimization (BayesOpt), a sequential optimization strategy, for the multi-material design problems. In this work,we select two base materials with distinct elastic moduli and use the proposed optimization scheme to design a composite solid that achieves a prescribed set of macroscopic elastic moduli. We fabricated optimal samples with multi-material 3D printing and performed experimental validation, showing that the optimization framework is reliable.

MEDIA: SHAKERS AND MOVERS

I am so honored to be featured in the “Shakers and Movers” interview series. In the spirit of the key theme of ‘Inspiring the next generation,’ this series aims to reach out and encourage young people to enter the field of spatial structures, as well as to motivate everyone involved in this field. Read more in the link below

https://epubs.surrey.ac.uk/858369/1/A4_Movers%20%26%20Shakers_v9_High_Res.pdf

JOURNAL PUBLICATION: Adjoint optimization of pressurized membrane structures using automatic differentiation tools

This paper presents an adjoint-based method for solving optimization problems involving pressurized membrane structures
subject to external pressure loads. Shape optimization of pressurized membranes is complicated by the fact that, lacking bending stiffness, their three-dimensional shape must be sustained by the internal pressure of the inflation medium. The proposed method treats the membrane structure as an immersed manifold and employs a total Lagrangian kinematic description with an analytical pressure–volume relationship for the inflating medium. To demonstrate the proposed method, this paper considers hydrostatically loaded inflatable barriers and develops an application-specific shape parametrization based on the analytical inhomogeneous solution for the inflated shape of cylindrical membranes. Coupling this shape parametrization approach with the adjoint method for computing the gradients of functionals enables a computationally efficient optimization of pressurized membrane structures. Numerical examples include minimization and minimax problems with inequality and state constraints,which are solved considering both plane strain and general plane stress conditions. The numerical implementation leverages the
high-level mathematical syntax and automatic differentiation features of the finite-element library FEniCS and related librarydolfin-adjoint. The overall techniques generalize to a broad range of structural optimization problems involving pressurized membrane and thin shell structures.

JOURNAL PUBLICATION: Shape optimization of arches for seismic loading

In this paper a novel method for the shape optimization of tapered arches subjected to in-plane gravity (selfweight) and horizontal loading through compressive internal loading is presented. The arch is discretized into beam elements, and axial deformation is assumed to be small. The curved shape of the tapered arch is discretized into a centroidal B-spline curve with beam elements. Constraints are imposed for allowable axial force and bending moment in the arch so that only compressive stress exists in the section. The computational cost for optimization is reduced, and the convergence property is improved by considering the locations of the control points of B-spline curves as design variables. The height of section is also modeled using a B-spline function. A section update algorithm is introduced in the optimization procedure to account for the contact and separation phenomena and to further speed up the computation process. The objective function to minimize the total strain energy of the arch under self-weight and horizontal loading. Numerical examples are presented that demonstrate the effectiveness of the proposed method. To validate the findings, the properties of the obtained optimal shapes are compared to shapes obtained by a graphic statics approach.

JOURNAL PUBLICATION: A data-driven computational scheme for the nonlinear mechanical properties of cellular mechanical metamaterials under large deformation

Cellular mechanical metamaterials are a special class of materials, whose mechanical properties are primarily determined by their geometry. But capturing the nonlinear mechanical behavior of these materials, especially with complex geometries and under large deformation can be challenging due to the inherent computational complexity. In this work, we propose a data-driven multiscale computational scheme to as a possible route to resolve this challenge. We use a neural network to approximate the effective strain energy density as a function of cellular geometry and overall deformation. The network is constructed by “learning” from the data generated by finite element calculation of a set of representative volume elements at cellular scales. This effective strain energy density is then used to predict the mechanical responses of cellular materials atlarger scales. Compared with direct finite element simulation, the proposed scheme can reduce the computational time up to two orders of magnitude. Potentially, this scheme can facilitate new optimization algorithms for designing cellular materials of highly specific mechanical properties.

PRESENTATION: Amortized Finite Element Analysis for Fast PDE-Constrained Optimization

Optimizing the parameters of partial differential equations (PDEs), i.e., PDE-constrained optimization (PDE-CO), allows us to model natural system from observations or perform rational design of structures with complicated mechanical, thermal, or electromagnetic properties. However, PDE-CO is often computationally prohibitive due to the need to solve the PDE—typically via finite element analysis (FEA)—at each step of the optimization procedure. In this paper we propose a mortized finite element analysis (AmorFEA), in a neural network learns to produce accurate PDE solutions, while preserving many of the advantages of traditional finite element methods. This network is trained to directly minimize the potential energy from which the PDE and finite element method are derived, avoiding the need to generate costly supervised training data by solving PDES with traditional FEA. As FEA is a variational procedure, AmorFEA is a direct analogue popular amortized inference approaches in latent variable models, with the finite element basis acting as the variational family. AmorFEA can perform PDE-CO without the need to repeatedly solve the associated PDE, accelerating optimization when compared to a traditional workflow using FEA and the adjoint method.

KEYNOTE: A different perspective on shells

I am very grateful that the organizers of the 1st Italian Workshop on Shell and Spatial Structures went on-line and gives us the opportunity to connect and discuss our research in a keynote.

FUNDING: Fabrication-Informed Design: Building Efficient Structures with Cooperative Robotic Fabrication Methods

The aim of the collaborative research is to develop design and construction techniques to build geometrically complex, but materially efficient, structural forms. Designing structures with cooperative robotic approaches in mind has the potential to reduce the amount of waste (e.g. scaffolding and off-cuts) that is generated during the construction process of these efficient but complex form-found structures.

MEDIA: The Times “Hi-tech sleuths reveal dome truths”

In one of today’s leading articles of the Times, our study on the role of the herringbone brick spirals in the stability of the Italian Renaissance Domes, like the Duomo in Florence, is discussed.

Generations of pilgrims, tourists and architecture students have marvelled at the splendour of Italy’s Renaissance domed churches and cathedrals. But as the visitors wondered, the secret of how these majestic buildings came to be has remained elusive.

Despite their fabulous wealth, popes and merchant princes did not care for the expense of traditional building methods, which would have used elaborate wooden frames to support brickwork spans — and in any case, timber was in short supply. So how were they built? Modern technology has finally provided the answer: it is all down to geometry.

Engineers have used computer analysis to show how the architect Antonio da Sangallo perfected a complex double-helix design to build domes without the usual temporary timber centering. more here

JOURNAL PUBLICATION: Statics of self-balancing masonry domes constructed with a cross herringbone spiraling pattern

The Brunelleschi herringbone pattern was certainly known by the Sangallo in the 16th century, who developed their own self-balanced construction technology for masonry domes based on the cross-herringbone spiraling pattern. Such technology was used for over one century in Italy to build masonry domes without shoring and formwork. However today it is not well known how this cross-herringbone spiraling pattern enables equilibrium states of self-balancing masonry domes. Therefore, in this study we demonstrate how this pattern permits equilibrium states of an octagonal masonry dome using two analysis approaches (i.e. Discrete Element Model and Limit State Analysis). The Discrete Element Model analysis has been performed to show the existence of the plate-bande resistance within the pattern. Even in the construction stages, these plate-bande resistance systems are capable of preventing sliding and overturning of the masonry dome. With the global self-balanced static equilibrium state proven, a Limit State Analysis is then adopted to estimate a possible thrust configuration needed to achieve equilibrium of the plate-bandes and the whole dome at each construction stage. It is shown that the value of the mortar friction has little influence on the static behavior of the dome. The study of the cross herringbone spiraling pattern does not merely serve historical or conservation purposes. It has practical application for the development of dry self-balanced robotic masonry construction technologies, particularly suited for unmanned aerial vehicles.

JOURNAL PUBLICATION: Occupant-centered optimization framework to evaluate and design new dynamic shading typologies

Dynamic solar shading has the potential to dramatically reduce the energy consumption in buildings while at the same time improving the thermal and visual comfort of its occupants. Many new typologies of shading systems that have appeared recently, but it is difficult to compare those new systems to existing typologies due to control algorithm being rule-based as opposed to performance driven. Since solar shading is a design problem, there is no single right answer. What is the metric to determine if a system has reached its optimal kinematic design? Shading solutions should come from a thorough iterative and comparative process. This paper provides an original and flexible framework for the design and performance optimization of dynamic shading systems based on interpolation of simulations and global minimization. The methodology departs from existing rule-based strategies and applies to existing and to complex shading systems with multiple degree-of-freedom mobility. The strategy for control is centered on meeting comfort targets for work plane illuminance while minimizing the energy needed to operate space. The energy demand for thermal comfort and work plane daylight quantity (illuminance) are evaluated with Radiance and EnergyPlus based on local weather data. Applied to a case study of three typologies of dynamic shading, the results of the methodology inform the usefulness and quality of each degree-of-freedom of the kinematic systems. The case study exemplifies the iterative benefits of the methodology by providing detailed analytics on the behavior of the shades. Designers of shading systems can use this framework to evaluate their design and compare them to existing shading systems. This allows creativity to be guided so that eventually building occupants benefit from the innovation in the field.

FUNDING: GLOBAL COLLABORATIVE NETWORK AT PRINCETON

The research goal of the network is to develop an overarching methodology of systems, methods and processes based on the integration of mechanics, robotics, physics, material and computer science principles. Collectively, the network’s methodological insights and research findings are expected to uncover comprehensive approaches and contribute to a robust sustainable built environment.  The key components of our network are: (i) exchange opportunities for graduate students and faculty, (ii) a seminar series and workshop, (iii) co- teaching of a new undergraduate course “Origami and morphing structures”, (iv) joint journal and conference publications and (v) an annual industry advisory board meeting.

JOURNAL PUBLICATION: How and Why Laurent Ney Finds Steel Structural Forms

The talent, knowledge and approaches of the structural designer Laurent Ney (1964-present) are increasingly recognized by engineering, architecture and construction awards. Most of the writing on his work has focused on his design philosophy or on individual projects. The aim of this paper is threefold: 1) to provide a social, historic and geological context for his work, 2) to showcase how he masters digital and numerical shape finding and optimization approaches to inform his design and construction decisions and 3) to illustrate how his works revive underutilized public spaces and augment people’s happiness and well-being. The three chosen case studies are all large-span steel structures: one beam bridge (Centner) and two shell structures (steel/glass gridshell over the courtyard of the Dutch Maritime Museum and the hanging steel shell of the Knokke Lichtenlijn footbridge). The scholarship presented in this paper forms the basis for one of the contemporary lectures of CEE262 “Structures and the Urban Environment,” a course first taught by Prof. Billington in 1974 at Princeton University.

PRESENTATION: GEOMETRY AND TRANSFOMATION IN ANNE TYNG’S WORK

Connecting the technical and conceptual, the work of Anne Tyng stands out within and beyond the field of architecture. Through independent projects, in addition to her work with architects Louis Kahn and Pier Luigi Nervi, Tyng explored geometry as it relates to natural form and construction. She approached design as a process and profession through teaching and writing, addressing the social, psychological, and experiential dynamics of creativity and collaboration; her work has influenced other practitioners as well as models of practice. At the center of this conference is the question, “How do we position the legacy of an architect whose interests and methods remain relevant in contemporary discourse?” Anne Tyng: Ordered Randomness reconsiders established histories by tracing Tyng’s design approach through built and unbuilt works, and further explores continuing resonances of her work as found in current architectural and engineering practices.

Organized by Women in Design and Architecture (WDA), a graduate student group formed in 2014 at Princeton University School of Architecture, this annual conference celebrates the work and legacy of a pivotal female architect or designer with contributions from international historians and scholars, in addition to artists, curators, and practitioners.

FUNDING: NODES – Net Topology and Dance Exploration Systems

When dancers dynamically interacted with manmade nets in our choreographic piece “In*Tension” (Seattle, June 2019), the nets exhibited counterintuitive stiffness properties.  They stiffened under increased dancer impact loading and this phenomenon substantially differed for the orthogonal and bias net topologies. Historically, structural engineering has eschewed the design of structural nets, implicating their unsatisfactory stiffness as the cause of disastrous resonance and fatigue failures in, for example, cablenet building facades and impact net barriers.  We propose to harness the stiffening effect found in net topologies when they are driven into large displacements through dance to generate novel 3D resilient flexible systems nets with adaptive stiffness properties. The core concept is that, under external loading, the flexible net undergoes large displacements and stiffens, partially as a function the elastic stiffness of the net’s individual strands, but more as a function of its mesh shape, size, orientation, and arrangement.  Current structural net design occurs according to prescriptive guidelines that heavily restrict large displacements, while choreographic design focuses on expanding possibilities and here would maximize the dynamic interactions between the dancer and the net. The originality of the proposed research lies in harnessing the stiffening effect found in net topologies that are displaced unusually and extremely by dynamic dancer loading as a strategy to create resilient structural systems with force-dependent stiffness properties.

Our goals are to create choreographic works that generate a new understanding of how  different net topologies rigidify when loaded and soften when unloaded.

JOURNAL PUBLICATION: A 3-dimensional elastic beam model for form- finding of bending-active gridshells

In this paper, we present a 3-dimensional elastic beam model for the form-finding and analysis of elastic gridshells subjected to bending deformation at the self-equilibrium state. Although the axial, bending, and torsional strains of the beam elements are small, the curved beams connected by hinge joints are subjected to large-deformation. The directions and rotation angles of the unit normal vectors at the nodes of the curved surfaces in addition to the translational displacements are chosen as variables. Based on the 3-dimensional elastic beam model, deformation of an element is derived from only the local geometrical relations between the orientations of elements and the unit normal vectors at nodes without resorting to a large rotation formulation in the 3-dimensional space. Deformation of a gridshell with hinge joints is also modeled using the unit normal vectors of the surface. An energy-based formulation is used for deriving the residual forces at the nodes, and the proposed model is implemented within dynamic relaxation method for form-finding and analysis of gridshells. The accuracy of the proposed method using dynamic relaxation method is confirmed in comparison to the results by finite element analysis. The results are also compared with those by optimization approach for minimizing the total potential energy derived using the proposed formulation.

PRESENTATION: Lightweight Structures for a resilient urban environment

PRESENTATION: EXTREME STRUCTURES

PUBLICATION: Effect of Gravity on the Scale of Compliant Shells

Abstract: Thin shells are found across scales ranging from biological blood cells to engineered large-span roof structures. The engineering design of thin shells used as mechanisms has occasionally been inspired by biomimetic concept generators. The research goal of this paper is to establish the physical limits of scalability of shells. Sixty-four instances of shells across length scales have been organized into five categories: engineering stiff and compliant, plant compliant, avian egg stiff, and micro-scale compliant shells. Based on their thickness and characteristic dimensions, the mechanical behavior of these 64 shells can be characterized as 3D solids, thick or thin shells, or membranes. Two non-dimensional indicators, the Föppl–von Kármán number and a novel indicator, namely the gravity impact number, are adopted to establish the scalability limits of these five categories. The results show that these shells exhibit similar mechanical behavior across scales. As a result, micro-scale shell geometries found in biology, can be upscaled to engineered shell geometries. However, as the characteristic shell dimension increases, gravity (and its associated loading) becomes a hindrance to the adoption of thin shells as compliant mechanisms at the larger scales-the physical limit of compliance in the scaling of thin shells is found to be around 0.1 m.

Find our full paper here

SHOW: EXTRAORDINARY PROCESSES – EXTRAORDINARY BEDS

Our students in VIS and CEE 418 are showcasing their extraordinary sleeping platforms or “beds” in the Co_Lab at the Princeton Lewis Center for the Arts until February 3rd 2020. If you are around, be puzzled and dazzled by these extraordinary structures!

PRESENTATION: FORM FOLLOWS FORCE – EXTREME STRUCTURES FOR A RESILIENT URBAN ENVIRONMENT

I am delighted to present our newest work on architectural shells and membranes at the Applied Mechanics Colloquium at Harvard University on December 4th.

By 2050, 70% of the world’s population will live in cities. Civil engineers envision, design and construct structures that those city dwellers depend on daily. The construction industry is one of most resource‐intensive sectors, and yet our urban infrastructure continues to be built in the massive tradition in which strength is pursued through material mass. In contrast, I have focused my research on structural systems that derive their performance from their curved shape, dictated by the flow of forces. As a result, these structures can be extremely thin, cost‐effective, and have a smaller carbon footprint. My core research question is  ‘What is the relationship between form and efficiency in civil-scale structures?’ I will focus on the form finding and structural performance of rigid and compliant shells, and flexible net and rod networks with applications for a resilient urban environment. The applications include large-scale storm surge barriers, long-span buildings, adaptive building shading devices and submerged barriers.  Some of these systems are inspired by structures that have evolved in biology, art or craft.

MEDIA: Engineering, Beauty and a Longing for the Infinite

Today a superb piece on the deeper impact and importance of the PIIRS Global Engineering Seminar “Two Millennia of Structural Architecture in Italy.” (CEE463/CEE263), we taught this summer in Rome, appeared on the Scientific American blog.

INNOVATION: Solar shade and energy-efficient and comfort control system

Our innovation is featured in “Celebrate Princeton: Innovation 2019”. Come and see you on Thursday November 4th 2019, 5-8pm in Frick Chemistry Laboratory, Princeton University. Find out more here

AWARD: 2019 AIA Northwest and Pacific Region Merit Student Design Award

In*Tension, our collaborative project resulting for the Barry Onoue Studio at the University of Washington, has just won the 2019 AIA Northwest and Pacific Region Merit Student Design Award. Thank you students, the wonderful artists Janet Echelman, Rebecca Lazier and Samantha Boschnacks and my talented co-instructor Tyler Sprague! More about this project in our blog soon. And this only the beginning of a series of fascinating net project! Stay tuned!

PUBLICATION: Dynamic behavior of form-found shell structures according to Modal and Dynamic Funicularity

Civil thin shell structures are generally designed with the objective to achieve an ideal membrane behavior and pursuing criteria of structural efficiency and minimization of the material used. During the shell form finding process, gravity loads are considered, while the role of horizontal loading is ignored. Today shells with complex geometries are being designed and built, and are used to shelter people during extreme events such as earthquakes, but the dynamic behavior of civil thin shells has always been subjected to limited research. This paper investigates the effects of dynamic loading on the behavior of civil thin shells form-found under gravity loads. A two-phased methodology is presented. In the first phase a modal analysis of the shell is performed and the R-Funicularity Ellipse Method is applied to the modal stress distribution obtained to observe which modes show a more funicular behavior. In the second phase, the structure is analyzed performing a time-history analysis under single and multi frequencies spectra defined using ad hoc functions based on the outputs of phase one. The results of such a phased approach applied to benchmark studies, show that the frequency content of the different areas of the shell can give insights onto its membrane behavior. Finally the form-found shell is analyzed under the action of the L’Aquila Earthquakes (Italy, 2009) to prove how the methodology proposed can help to identify the vulnerable area of a shell under a real seismic event.

PUBLICATION BOOK CHAPTER: Structured Lineages: learning from Japanese Structural Design

MoMA Announces Publication on Japanese Structural Design from 1950 Through Today.
Structured Lineages: Learning from Japanese Structural Design presents a selection of essays and roundtable discussions by internationally prominent structural engineers on the intertwined traditions of architecture and engineering in postwar Japan.

PRESENTATION: EXTREME SHELLS

I am delighted to present our work that advances how to design and build earthquake resistant vaults at the University of Bergamo, Italy, on the 26th of July 2019.

FUNDING: “Designing Intelligent Structures that Learn and Adapt”

We are delighted to have been awarded Princeton Catalysis Initiative Funding for our research on smart structures and materials with Prof. Ryan Adams (COS).

PERFORMANCE: IN*TENSION

Nets, non-linear tensile systems, are form active when they interact with human bodies. They visualize fluid dynamics and can be bundled or fill a volume. They are strong, yet appear delicate. Join us for our structural/dance/architecture performance IN*TENSION on June 11th at 1pm Gould Hall, University of Washington, Seattle. This is event is the culmination of the Onouye Studio I co-taught with Tyler Sprague. We worked with the choreographer Rebecca Lazier and her dancers, the visual artist Janet Echelman, the engineer Clayton Binkley (Ove Arup) and the composer Samantha Broshnack.

CONGRATS TO OUR GRADS: Amber, Angel, Nyema and Victor

Valete and avete! Undergrads Amber Lin, Angel Fan, Nyema Wesley and Doctor Victor Charpentier graduated yesterday: all the best to you!

Amber won the SEAS Joseph Clifton Elgin Award and Nyema the CEE book Award. We are so proud.

OUTREACH: RESILIENCY AND BUILDINGS

We had the pleasure of holding workshops for 3rd, 4th and 5th graders at the Riverside Elementary School on how buildings can be designed to resist earthquakes. We made toothpick and marshmallow buildings and subjected them to shock waves induced in pan filled with jello, simulating liquefaction of soils. We had so much fun and learned a lot.

PRESENTATION: FORM FOLLOWS FORCE – WHY AND HOW DOES IT MATTER?

The Cherry Blossoms are blooming at eth University of Washington, Seattle and I am giving a public lecture in the School of Architecture, Gould Hall on April 3rd. Drop by if you are around!

PUBLICATION: Hygroscapes: Innovative Shape Shifting Facades

This chapter focuses on the testing and design of shape shifting façade prototypes that are programmed to passively sense stimuli and respond in a controlled setting based on the hygroscopic properties of wood. Wood is introduced in this context as a low-tech smart material with a naturally soft responsive mechanism that offers a substitute for mechanical actuators. First, a set of physical experiments were conducted to deduce the design parameters that affect wood morphology, behavior and response time upon changes in humidity levels and moisture content, including dimensional ratio, grain orientation, material thickness, type of wood, and lamination. We then report on the process and outcome of a workshop held at the American University in Cairo, with the main challenge of regulating the morphology and hygroscopic behavior of wood to work as an actuator with specifically desired motion for adaptive building façade prototypes. Based on the observations and analysis of concepts and mechanisms, we discuss shape shifting grammars as a framework for devising adaptive façade prototypes from a generative design perspective, where specific combinations of motion parameters are used to induce semantic rules and customized commands for the overall behavior of shape shifting mechanisms.


S. Abdelmohsen, S. Adriaenssens, G. Stefano, L. Olivieri, R. El-Dabaa, ‘Hygroscapes: Innovative Shape Shifting Facades’, in ‘Digital Wood Design: Innovative techniques of representation in Architectural Design’, 1st ed. F. Bianconi, M. Filippucci, Springer International Publishing, 2019, ISBN 978-3-030-03676-8.

PRESENTATION: Form Finding of Shells for Extreme Loading and Environmental Stress

I thoroughly enjoyed presenting our most recent work on rigid and semi-flexible shells with civil applications at Rutgers University on February 13th.

FUNDING: Intellectual Property Accelerator Fund

We are delighted to have been awarded Intellectual Property Accelerator Funding to pursue the development of our bio-InspiRed adaptive Shading Device (IRiS)

PRESENTATION: BIOMIMETIC MORPHING SHAPES

Our work on biomimetic morphing shapes drew attention at the Hygroscapes Workshop 3, held at Roma Tre University, Rome (Jan 2019)

FUNDING: HARNESSING LARGE DEFORMATIONS IN INTERLACED ELASTIC NETWORKS

In mechanics, large deformations can occur at both the material and structural scales. In the past, structural engineering has eschewed large deformations, implicating them as the cause of several disastrous failures of rigid structures. However, attention is now turning to how to take advantage of large deformations. Therefore, we propose to investigate 2D interlaced networks of elastic rods and deliberately drive them into the large deformation realm to create novel 3D elastic (and thus reversible) structures with interesting mechanical properties. The core concept is that, under compression, the interlaced continuous rods will bend, twist, and slide with respect to each other, forcing the 2D network into three dimensions in order to minimize the network’s strain energy. The research objectives of this proposal are threefold: to 1) use a mathematical approach to identify interlaced patterns for the purpose of shifting between 2D and 3D states, 2) investigate their reversible mechanical response and establish their performance envelope using an experimental and numerical approach, and 3) design, prototype, and demonstrate the feasibility of interlaced elastic networks at the architectural scale using robotic manufacturing.

PUBLICATION: Form finding of corrugated shell structures for seismic design and validation using non-linear pushover analysis

The geometry of shell structures plays an essential role in their capacity to withstand earthquakes. However seismic loading is rarely considered when determining the overall geometry of shells. This paper presents a novel form finding methodology for the conceptual seismic design of corrugated shells. The method ensures that a compression load path exists to carry lateral earthquake accelerations by deriving shell geometries from a series of funicular polygons obtained through a graphic statics procedure for combined gravity and horizontal loads. While the method can be applied to any material that resists compressive stresses, it is employed in this paper to find the shapes of corrugated thin-tile masonry shells. Non-linear pushover analysis is then used to quantify lateral capacity and evaluate form finding results in terms of material efficiency to resist lateral loads. The analysis furthermore provides insights regarding the collapse mechanisms and flow of forces. It is demonstrated that the lateral capacity before cracking in the corrugated shell shapes is up to 79% higher than the capacity of a non-form-found reference shell shapes considering identical material use. All form-found shells were found to fail through a similar collapse mechanism which is defined by four crack zones. The location of these crack zones can be manipulated through the form finding process and identify the locations where reinforcement could be most efficiently introduced. Finally, the flow of forces within the form-found shells is used to propose alternative designs that provide additional openings in the shell surface while maintaining similar seismic capacity. Thus, the paper provides a new approach for the conceptual design of safe corrugated shell structures in earthquake prone areas.

FUNDING: NOISE POLLUTION, BARRIERS, HEALTH, EQUITY AND THE CITY

Noise pollution is a growing problem that affects our physiological and psychological health. Despite noise codes being reinforced through local laws, a complaint is deposited every four minutes in a city like New York or Trenton. In this project, we establish the relationship between the health effects of noise pollution and the socio-economic status of areas in Trenton. To start tackling the noise pollution in those areas, we envisage novel esthetic noise barriers to effectively create quieter regions. However, designing such barriers is a challenging task due to i) absence of literature on noise pollution in Trenton; and ii) the temporal nature and range of the noise levels that need to be absorbed by the barriers. This project will explore these challenges and solutions.

PUBLICATION: A multi-physics approach for modeling hygroscopic behavior in wood low-tech architectural adaptive systems

Wood is a natural engineering material that has traditionally been exploited in design for a wide variety of applications. The recent demand for sustainable material and construction processes in the construction industry has triggered a renewed interest and research in the inherent properties of wood and their derived applications, and specifically for developing low-tech architectural adaptive systems. This paper focuses on the physical and computational modeling of the morphing behavior of wood through hygroscopic expansion or contraction to a high degree of precision. The amount of stress related to the hygroscopic shrinking or swelling ranges from almost zero to high values, and its prediction is fundamental to alleviate any fatigue challenges. The capability of designing wood composite whose stress state remains limited under changes of the environmental humidity is beneficial for any engineering application subjected to a repeated reversal of loading such as adaptive systems. In this paper, a mechanical model, together with its numerical implementation is presented; the model is benchmarked against and some prototypical experiments, performed by using real material parameters The control parameter in the model is the relative moisture change in wood, that determines the orthotropic swelling/de-swelling phenomenon, and is coupled with the elastic behavior of wood. This model is integrated into a programmable matter design approach that combines physical and computational exploration. The approach is illustrated for a hygro-morphic building façade panel. The approaches and algorithms presented in this paper have further applications for computer-aided design of smart materials and systems with interchanging functionalities.

FUNDING: Planning Grant: Engineering Research Center for Naturally Inspired Resilient, Sustainable and Adaptable Infrastructure

The overall goal of this planning grant is to develop the team and structure of transdisciplinary convergent research that examines the attributes of resilient ecosystems, create collaborations between innovative researchers able to work across disciplinary boundaries, embrace diversity in teaming on multiple levels and construct an infrastructure that allows for collaborative research, development of innovative pedagogical approaches, and supports economic development through tech transfer.

2018 IASS: CREATIVITY IN STRUCTURAL DESIGN

Here are the papers we are presenting:

S. Gabriele, S. Adriaenssens, L. Teresi . ‘Modeling the physics of hygromorphic adaptive surfaces‘ in IASS 2018: Creativity in Structural Design, Massachusetts, 2018.

Addi K., Niewiarowksi A. , Pauletti R. , Adriaenssens, S. ‘Parametric topology study of cable-net systems under cyclic loading’, in IASS 2018: Creativity in Structural Design, Massachusetts, 2018.

V. Charpentier,  S. Adriaenssens, O. Baverel Compliant 2-dof mechanism based on elasticity of thin shells ‘, in IASS 2018: Creativity in Structural Design, Massachusetts, 2018.

R. Pauletti, S. Adriaenssens, A. Lin ‘Numerical modeling of the activation and the snap-through instability of a bending-active umbrella’, in IASS 2018: Creativity in Structural Design, Massachusetts, 2018.

G. Tomasello, S. Gabriele, S. Adriaenssens R-Funicularity of shell structures under dynamic load: the influence of the shape’, in IASS 2018: Creativity in Structural Design, Massachusetts, 2018.

T.   Michiels, M. Dejong, S. Adriaenssens Employing thrust lines to find the optimal form of corrugated shells designed to withstand earthquakes’, in IASS 2018: Creativity in Structural Design, Massachusetts, 2018.

IABSE HENDERSON COLLOQUIUM: How to design the next generation of adaptive structures?

This is what I talked about: The metaphor of a city as an Urban Metabolism, as a living organism that encompasses material and energetic streams from the inorganic construction of settlements, was first introduced by the pioneering ecologist Arthur Tansley.  To be able to apply this concept to urban design, the different urban flows, scales and the corresponding infrastructures need to be understood. The design and engineering of these infrastructures is directly linked to the quality of Urban Metabolism. Current digitization and upgrading of traditional cities pushes us towards “Adaptive” Infrastructure. Adaptive Infrastructure manages urban flows and allows for real-time responses. In my research I focus on the development of novel adaptive structures, that can be equipped to be intelligent, knowledgeable and systematic. I draw on rigid body motions, found in linkages and origami, and elasticity, found in nature, to tailor the deployment and service behavior for novel bridge and architectural façade systems.  These systems exhibit remarkable properties of low actuation energy and variable stiffness amongst others.  I am excited to share the research and development of these systems and foresee their application in the domain of Adaptive Infrastructure.

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PUBLICATION: Modeling underwater cable structures subject to breaking waves

This work explores the design problem of a cable net shark barrier. Protective cable net barriers are generally accepted as the most acceptable approach to preventing shark attacks, but their adoption has been hampered by high costs of maintenance. As with any structural design, to achieve high reliability at low cost, it is paramount to investigate and select the most appropriate form. This work focuses on the effect of the mesh shape. The software OrcaFlex is used to analyze different mesh shapes subject to variable wave heading. The mechanical behaviors of six regular net configurations is presented and compared in terms of their cumulative tensile load histories. In general, the results indicate that the use of vertically orientated elements should be minimized to more evenly distribute the internal forces. This research is of relevance to the analysis and design of moored cable structures.

A. Niewiarowski, S. Adriaenssens, R.M.O. Pauletti, K. Addi, L. Deike, ‘Modeling underwater cable structures subject to breaking waves ‘, Ocean Engineering, vol. 64, 15, pp. 199-211.https://doi.org/10.1016/j.oceaneng.2018.06.013

PUBLICATION: Seeking congruency in digital optimisation and constructability in fabric formed ice shells utilising bending active frames

Fabric formed structures are widely used to produce structural forms through the use of a temporary rigid framing to support a flexible membrane as formwork. Recent research has sought to introduce flexible support systems for fabric formwork so that they may participate in the parametric behaviour of fabric, while providing useful constraints for design. In the project presented here, a bending active frame is used to create a fabric formed ice shell using this approach. A focus is placed on the use of ice as a temporary structural
material that allows for the iterative accumulation of mass during construction, as well as an analogous material for speculating about the use of other more permanent liquid-to-solid materials (like concrete). This project presents novel construction methods seeking to establish a meaningful link between digital optimisation design techniques and the often incongruent realities that must be
confronted to build such a structure.

CONGRATS TO OUR GRADUATE STUDENTS ANDREW AND TIM!

Avete atque valete. Andrew Rock and Tim Michiels were hooded and graduated on June 4th and 5th. They will go on to do great things.

PUBLICATION: Assessing the stability of unreinforced masonry arches and vaults: a comparison of analytical and numerical strategies

Despite being accepted as a robust assessment of masonry stability, thrust line analysis (TLA) relies on assumptions that can lead to a conservative assessment of stability. This article aims to quantify the extent of these limitations through a comparison of TLA with discrete element modeling (DEM). Two studies are provided. The first study compares TLA with DEM (using fixed input parameters) in assessing the stability of unreinforced masonry arches, semi-circular barrel
vaults, multi-ring arches, and groin vaults. The tests demonstrate the types of sliding failures overlooked by the safe theorem due to its assumption of infinite friction. Following these validations, the comparisons between 2D structures and 3D counterparts also give insight into the efficacy of the slicing method. The second study examines the effect of DEM input parameters on the DEM-predicted stability of the considered geometries. While material parameters had limited effect on the determination of stability, for each typology, joint friction angle had a unique impact on stability. These trends are graphically presented and demonstrate how t/R ratios alone are not sufficient to unequivocally confirm stability of the considered vaults. Overall, this research informs the extent of safety for using the geometry-based analysis tool, TLA, for
analyzing masonry structures.

CONGRATS: TIM SUCCESSFULLY DEFENDS HIS PhD THESIS

Congratulations to Tim Michiels who successfully presented his doctoral research on Monday! You can see his presentation video on the Form Finding Lab Facebook page.

AWARD AND PRESENTATION: ASCE STRUCTURES CONGRESS

We are at the ASCE SEI Congress in Fort Worth, Texas to present our innovative course CEE546 “Form Finding of Structural Surfaces” and to receive the ASCE George Winter Award.

FUNDING: SHELLS AND DOMES IN SEISMIC REGIONS

Thin structural shells have shown to be inherently able to withstand earthquakes, but the reasons for this apparent seismic resistance have only been partially reported in literature, and never well studied. Shells exhibit a high structural efficiency, meaning they can be very thin, and thus have a low carbon footprint. Because of their lightweight nature, earthquake forces induced in a thin shell structure are relatively low. However, the shape of a shell structure is typically established so that it performs optimally under gravity loads (such as self-weight), carrying the loads to the foundations mainly through membrane action over the shell surface. Unanticipated horizontal forces induced by earthquakes generate bending stresses in shell structures, which could lead to structural damage.  The relevance of our shared research interest in the study of shells and domes in seismic regions is a direct consequence of the high incidence of earthquakes in Italy and the west coast of the United States of America, and the potential of shells and domes to be safe havens for local communities during such an event. Therefore, together with the University of Roma Tre we seek to build a collaborative research project on how to evaluate and exploit the potential shells and domes in seismic regions.  If successful, the strategies developed in this collaboration will help mitigate the devastating effects of earthquakes in cities and improve the well-being of its inhabitants.

PANEL: ENGINEERING AND THE SMART SUSTAINABLE CITY

We discussed what will a smart sustainable city look like from an engineering perspective at the Woodrow Wilson School of Public and International Affairs Conference on Smart Cities and Innovations in Urban Government,

FUNDING: ENGINEERING DESIGNS OPTIMIZED FOR PEOPLE’S PERCEPTION OF ESTHETICS

We are super happy to our proposal to generate new knowledge of how systems can be engineered to be not only efficient and economic, but also be perceived as being esthetic, has been funded by the Council for Science and Technology. This research project is the first collaboration between the research groups of Prof. Adriaenssens (Department of Civil and Environmental Engineering CEE) and Prof. Todorov (Department of Psychology PSY). The scholarship of both groups is focused on forms, namely the generation of structural forms and the perception of abstract forms respectively and Prof. Todorov (Department of Psychology PSY). The scholarship of both groups is focused on forms, namely the generation of structural forms and the perception of abstract forms respectively

AWARD: Prof. Adriaenssens wins the 2018 ASCE George Winter Award

Prof. Adriaenssens will be awarded the 2018 ASCE George Winter Award at the ASCE Structures Conference in Fort Worth, Texas. This award is important to us as it recognises the value of the integration of engineering and art in our work.

In the words of ASCE:

“The George Winter Award is intended as a recognition of the achievements of an active structural engineering researcher, educator or practitioner who best typifies the late Dr. George Winter’s humanistic approach to his profession: i.e., an equal concern for matters technical and social, for art as well as science, for soul as well as intellect. “

WELCOME TO TWO STUDENT RESEARCH COLLABORATORS

In this new year, we welcome Giulia Tomasello and Martina Russo from Roma Tre and Sapienza University of Rome respectively to work with us on (historic) shell structures.

PUBLICATION: PARAMETRIC STUDY OF SHELLS FORM-FOUND FOR SEISMIC LOADING

In this paper, a form finding approach is presented that allows for the shape generation of masonry shells in seismic areas. Through a parametric study, this method is illustrated for a wide variety of boundary conditions and leads to a set of shapes for double layer thin shells. Earlier studies have shown that continuous shells behave well during earthquakes due to their high stiffness and low mass. Additionally, there is a renewed interest in constructing masonry shells because of their low carbon impact, spurring the need to understand how such shells should be designed in seismic areas. Currently available form finding techniques for shells, however, rely solely on gravity loads for the generation of their shape and do not account for seismic loading. The form finding approach examined here is based on the generally accepted assumption that masonry structures cannot resist tensile stresses. Therefore, for masonry shells subjected to both vertical gravity and horizontal seismic loading, a compression-only load path (in 2D often referred to as a thrust line) should be present within the thickness of the shell to avoid collapse mechanisms. Through the application of an inversed hanging chain model subjected to lateral loading in a dynamic relaxation solver, shell forms are generated for which it can be ensured that such a load path exists. To illustrate this methodology, a variety of shapes are generated based on a set of parameters including boundary conditions and net stiffness. The shapes discussed in this paper are the first instances of compression only shells reported in literature, whose forms are successful and efficient in withstanding combined gravity/seismic loading. This paper’s findings demonstrate how to tailor masonry shells for a resilient built environment and can be extended to the shape generation.

INVITED TALK: KYOTO UNIVERSITY

Our latest work on form finding of shells under extreme loading will be presented and discussed next week (17th of November) at Kyoto University. We look forward to the exchange of ideas of our presentation “Form Finding of Shells under Earthquake Loading”.

INVITED TALK: TOKYO UNIVERSITY OF TECHNOLOGY

By 2050, 70% of the world’s population will live in cities. Structural engineers envision, design and construct the bridges and long‐span buildings those city dwellers depend on daily. The construction industry is one of most resource‐intensive sectors, and yet our urban infrastructure continues to be built in the massive tradition in which strength is pursued through material mass. In contrast, I have focused my research on structural systems that derive their strength from their curved shape, dictated by the flow of forces. As a result, these structures can be extremely thin, cost‐effective, and have a smaller carbon footprint. My research questions are ‘What is the relationship between form and efficiency in structures?’ and ‘How can algorithms and methodologies transform our construction approach from a massive tradition to a design framework for a lightweight, force‐ modeled built environment that contributes to our quality of life?’ I will demonstrate this approach for the design of footbridges, cupolas, building facades and coastal structures.

PUBLICATION: Identification of key design parameters for earthquake resistance of reinforced concrete shell structures

Concrete roof shells have shown to be inherently able to sustain earthquakes, but the reasons for this apparent seismic resistance have been subject to limited research. Concrete shells exhibit a high structural efficiency and thus can be constructed very thin. Because of their relative lightweight nature, the earthquake forces induced in a thin shell structure are relatively low. However, the shape of a shell structure is typically established so that it performs optimally under gravity loads, carrying the loads to the foundations mainly through membrane action over the shell surface. Unanticipated horizontal forces induced by earthquakes generate bending stresses in concrete shell structures, which could lead to structural damage. Through a parametric study of 8 cm thick, concrete roof shells with a square plan, the research presented in this paper demonstrates that small to mid-sized (span < 15 m) thin concrete roof shells can indeed be intrinsically earthquake resistant. They owe this resistance to their great geometric stiffness and low mass, which lead to high fundamental frequencies that are well above the driving frequencies of realistic seismic actions. Due to these characteristics the shells analyzed in this paper behave elastically under the earthquake excitation, without surpassing the maximum allowable concrete strength. For shallow shells it is observed that the vertical components of the earthquake vibrations, can induce larger stresses in the shell than the horizontal components. It is further demonstrated that by increasing the rise and curvature of larger shells (20 m by 20 m), their fundamental frequencies are increased and the damaging effect of the vertical earthquake vibration components mitigated.

PUBLICATION: Form-finding algorithm for masonry arches subjected to in-plane earthquake loading

This paper presents the first form finding method for masonry arches subjected to self-weight and inplane
horizontal loading due to earthquakes. New material-efficient arch shapes are obtained by considering
both horizontal and gravitational acceleration in the form finding process. By interpreting the
obtained forms, insights into the influence of form on the earthquake resistance of the arches are presented.
The form finding algorithm relies on two simplified, first-order equilibrium methods: thrust line
analysis and kinematic limit state analysis, which present respectively a lower- and upper-bound
approach to the analytic problem of arch stability under gravity and horizontal loading. Through a
methodological application of a series of geometric manipulations of the thrust line, shapes are obtained
that can resist the design acceleration by guaranteeing a compression-only load path. Forms are obtained
for horizontal accelerations of 0.15, 0.3 and 0.45g, as well as for arches of different rise-to-span ratios
(1/2, 1/4 and 1/8). The obtained shapes require up to 65% less material than circular arches with constant
thickness that are designed to withstand the same horizontal acceleration and self-weight, regardless of
acceleration magnitude. The findings of this research will thus allow more material-efficient design of
masonry arches in seismic areas.

AWARD: TIM MICHIELS WINS THE HANGAI AWARD

Yesterday our PhD Candidate Tim Michiels was awarded the Hangai prize for his “Outstanding paper by a young talented researcher under 30” at the annual symposium of the International Association of Shell and Spatial Structures (IASS) in Hamburg. Tim presented his research titled “Parametric study of masonry shells form found for seismic loading” during the plenary session on Tuesday. Tim’s award marks the 3rd consecutive prize for the Form Finding Lab at the yearly IASS conference, after Edward Segal et al.’s Tsuboi prize in Amsterdam (2015) and the stadium competition won by Olek Niewiarowski in Tokyo (2016) last year.  You can read more about Tim’s work in our blog post here.

PRESENTATION: IASS shells, nets, membranes

Here they are:

L. Coar, M. Cox, S. Adriaenssens, L. de Laet, ‘The design and construction of bending active framed fabric formed ice shells utilizing principle stress patterns’, in IASS 2017: Interfaces, Hamburg, Germany, 2017.

S. Gabriele, S. Adriaenssens, V. Varano, G. Tomasello, ‘Modal funicularity of shell structures’ in IASS 2017: Interfaces, Hamburg, Germany, 2017 .

A. Niewiarowski, S. Adriaenssens,R.M. O. Pauletti, K. Addi ‘ Cable net systems under dynamic loading: an overview of appropriate numerical modeling techniques’ in IASS 2017: Interfaces, Hamburg, Germany, 2017.

T. Michiels, S. Adriaenssens, J.J. Jorquera-Lucerga ‘ Form Finding of Shells in Earthquake Zones’ in IASS 2017: Interfaces, Hamburg, Germany, 2017.

R.M. O. Pauletti, S. Adriaenssens, A. Niewiarowski, V. Charpentier, M. Coar, T. Huynh, X. Li’ A minimal Surface Membrane Sculpture’ in IASS 2017: Interfaces, Hamburg, Germany, 2017.

LECTURE: UNIVERSITEIT VAN GENT

I am delighted to be presenting our research tomorrow at the University of Ghent, where I am a guest professor during my well-deserved sabbatical. “In pursuit of better urban forms” at Labo Magnel, University of Ghent, Science Park, Zwijnaarde.

COMMENDATION: OUTSTANDING TEACHING OF CEE546

Prof. A. has been commended for her outstanding teaching of CEE546 “Form Finding of Structural Surfaces”, a unique course that brings together graduate architecture and engineering students. The Princeton Engineering Commendation List for Outstanding Teaching will be published in Fall in the Daily Princetonian and the SEAS webpage. Thank you graduate students!

PUBLICATION: Kinematic amplification strategies in plants and engineering

While plants are primarily sessile at the organismal level, they do exhibit a vast array of movements at the organ or sub-organ level. These movements can occur for reasons as diverse as seed dispersal, nutrition, protection or pollination. Their advanced mechanisms generate a myriad of movement typologies, many of which are not fully understood. In recent years, there has been a renewal of interest in understanding the mechanical behavior of plants from an engineering perspective, with an interest in developing novel applications by up-sizing these mechanisms from the micro- to the macro-scale. This literature review identifies the main strategies used by plants to create and amplify movements and anatomize the most recent mechanical understanding of compliant engineering mechanics. The paper ultimately demonstrates that plant movements, rooted in compliance and multi-functionality, can effectively inspire better kinematic/adaptive structures and materials. In plants, the actuators and the deployment structures are fused into a single system. The understanding of those natural movements therefore starts with an exploration of mechanisms at the origins of movements. Plant movements, whether slow or fast, active or passive, reversible or irreversible, are presented and detailed for their mechanical significance. With a focus on displacement amplification, the most recent promising strategies for actuation and adaptive systems are examined with respect to
the mechanical principles of shape morphing plant tissues.

PUBLICATION: Comparison of thrust line analysis, limit state analysis and distinct element modeling to predict the collapse load and collapse mechanism of a rammed earth arch

This paper assesses the suitability of two analytical and one numerical analysis techniques to determine the collapse load and the collapse mechanism of a rammed earth arch. The first method, based on thrust line analysis, is a graphic statics based approach that can predict collapse relying only on material properties of density and compressive strength, assuming that rammed earth has no tensile strength. The second method, limit state analysis, is based on a virtual work formulation to predict the collapse assuming the same set of material properties. Both analytical methods have been adapted from masonry analysis to take into account the limited compressive strength of rammed earth to better predict the rammed earth arch’s behavior and can be generalized to any material without tensile strength. The third method is based on a distinct element modeling technique. It is shown through a comparison with a load testing experiment of a 2 m span rammed earth arch that thrust line analysis is an excellent tool to predict the collapse load, but that it cannot provide decisive information regarding collapse mechanisms. Limit state analysis, in contrast, is very suitable to determine the collapse mechanism but may underestimate the ultimate load capacity if the location where cracks can form is not known in advance. Distinct element modeling can provide accurate information on both collapse mechanism and collapse load, but is more computationally demanding and requires a comprehensive characterization of material properties. The application of these techniques to rammed earth is motivated by the rise of the design of new arched and curved rammed earth structures, while appropriate analysis tools are lacking.

PRIZE: DEMI FANG ’17 WINS SEAS MacCracken AWARD and CEE David W. Carmichael Prize

Class Day and Graduation. It was such a pleasuring working with these multi-talented students. I am delighted that Demi Fang won the MacCracken Award and the David W. Carmichael Prize. Well deserved!

ELECTED: EXECUTIVE COUNCIL IASS

Prof. Adriaenssens has been elected to the Executive Committee of the International Association for Shell and Spatial Structures.

SPECIAL ISSUE: New Directions for Shell Structures

Philippe Block (ETH Zurich) and I co-edited a special issue on how key challenges such as geometry, design and analysis methods, construction and new materials, can be overcome to bring thin shell structures into the 21st Century.

SEMINAR: FUTURE OF DESIGN

Bill Washabaugh (Hypersonic) and I talked about how biomimicry is key to the future of Design ‘Future of Design 2017’, IABSE US group, Many Cantor Center, April 2017.

PUBLICATION: DESIGN OF THREE HYPAR ROOFS MADE OF GAUDUA BAMBOO

While seeking new ways to build inexpensive and attractive shells, designers have increasingly been exploring shells and space structures made of guadua bamboo. Guadua bamboo poles, with their relatively low mass, high strength, and great axial and bending stiffness are promising linear building components for curved grid systems. Guadua bamboo is also a sustainable building material that can be easily harvested and deployed to construct economically efficient and elegant yet durable large span roofs. However, rigorous numerical structural analyses of bamboo are not common practice. Therefore, we present the structural analysis of two roofs consisting of a set of hyperbolic paraboloid (hypars) (designer Greta Tresserra, Colombia, 2015) that are planned in Cali, a region where the giant bamboo species Guadua Angustifolia grows abundantly. Additionally, a prototype hypar built in Austria (designers Greta Tressera and Tim Michiels, Austria, 2016) is presented as well.
In this study we examine the relationship between the structural behavior of hypar grids and their most critical bamboo joint. A simplified analysis, as well as a finite element (FE) analysis is performed in order to determine how the overall hypar form influences the internal loads in the bamboo. Subsequently, the most critical joints that interconnect the bamboo poles are analyzed through laboratory testing. Particular attention is given to the “fish-mouth” connection with and without mortar inserts. A better understanding of the flow of forces in the hypar grid combined with a detailed quantification of the behavior of the “fish-mouth” joint, allows for a more informed and efficient use of the bamboo material used in Cali structures. More broadly, this study seeks to demonstrate how an eco-friendly, widespread and inexpensive material such as bamboo can be used at its full structural capacity for the design and construction of hypar roofs.

YOUNG WOMEN’S CONFERENCE

Tomorrow we share our excitement about our research an biomimetic adaptive facades at the Young Women’s Conference. We will meet with hundreds of young women aspiring to achieve a future career in STEM! Princeton University, Frist Building 23rd March 8am – noon

LECTURE: SHELL ZEITGEIST: ANDRE PADUART AND MARCEL BROODTHAERS

Civil shell structures mostly originated in Germany in the beginning of the 21st century, spurred by development of analytical “shell” theory and reinforced concrete. Their evolution in that century can be marked by 3 phases. These phases also happen to span the biological life of Belgian artist Marcel Broodthaers (1924-1976) who is , among other projects, known for his assemblies of shells of eggs and mussels. In this talk, I briefly describe the history of civil shell design and construction in Belgium in the 20th century and in particular I focus on the work of the civil engineer Andre Paduart (1914-1985), who operated in the same time and geographical space as Marcel Broodthaers.

TedX: Designing for strength, efficiency and beauty

By 2050, 70% of the world’s population will live in cities. Structural engineers envision, design and construct the bridges and long‐span buildings those city dwellers depend on daily. The construction industry is one of most resource‐intensive sectors, and yet our urban infrastructure continues to be built in the massive tradition in which strength is pursued through material mass. In December 2016, Professor Adriaenssens gave aTedX talk “Designing for strength, economy, and beauty” at the GeorgeSchool, PA. Her idea is that our bridges and buildings should derive their strength and stiffness not through material mass but from their curved shape, generated by the flow of forces. As a result, these structures can be extremely thin, cost‐effective, and have a smaller carbon footprint and arguably they can have an esthetic quality to them.

Check out the video and like it here

LANDSDOWNE VISITOR: Resilient and Sustainable Structural Forms

FUNDING: BARTLETT COLLABORATION WITH THE AMERICAN UNIVERSITY OF CAIRO

The purpose of adaptive building skins is to actively moderate the influence of weather conditions on the building’s interior environment. Current adaptive skins rely on rigid body motions, complex hinges and actuation devices. These attributes are obstacles to their broader adoption in low-carbon buildings. This project explores these challenges and solutions. The core idea of soft adaptive skins is that they exploit the systems’ elasticity to respond to stimuli. However, designing such a skin is a challenging task due to the interaction between geometry, elasticity and environmental performance. The research tasks are to i) identify concept generators, ii) carry out numerical feasibility studies, and iii) improve environmental response through optimization . If successful, these skins will reduce energy consumption in the construction industry. However at the heart of our proposal is the exchange of people and ideas.

 

PUBLICATION: LA FORM IMPORTA – OUR FIRST PUBLICATION IN SPANISH!

S. Adriaenssens, ‘Form Matters’, Revista Materia, Special Issue: Tecnologia: Material Digital, vol. 13., pp.76-83, 2016.

Master builders throughout history have made significant strides in exploiting forms to enclose three-dimensional spaces, to provide shelter and protection or to bridge voids, such as water and roadways. In the absence of numerical prediction methods, they resorted to of free forms as an architectural expression. Yet, structural performance as the main design driver is often excluded from the initial design process. The scholarship at the Form Finding Lab (Princeton University, USA) can be placed in a force-modelled tradition by pioneering novel numerical structural form generation approaches and unique structural performative forms. Three studies are presented that showcase the development of such techniques, which when craftfully manipulated, result in surprising shapes for structurally efficient footbridges, roofs and barriers.

 

PUBLICATION: BRICK / SYSTEMS

For those who want an inspiring FREE read to snuggle up next to the fire, check out BRICK/SYSTEMS, including contributions by renowned practicing architects, directors of research groups and architectural experimental ’young guns’.

 At first glance, this book may appear eclectic. It contains writings from architectural practice in a language and structure based on subjective views and experiences, combined with research contributions based on systematic design investigations of discrete computational systems. Discussions range from an undulating masonry wall at the University of Virginia erected by then-U.S. President Thomas Jefferson to agile robotic manufacturing processes and computational solver strategies based on graph networks. Conversely, the focus of this anthology is expressed directly in the title: bricks and systems. The basis for this theme is the work conducted at the Utzon(x) Research Group at Aalborg University, in combination with the rich tradition and implementation of masonry work in Denmark, which has attracted increasing attention from architectural practitioners and researchers alike. How should one understand this book, with its widely varied yet converging contributions? As stated by German architect Frei Otto, buildings should be understood as auxiliary means—they are not ends in themselves. We believe this book should be understood through the same lens. It connects, rather than concludes, and it aims to illustrate and identify new modes of working in architecture, particularly with regards to brickwork and other complex systems of modular assemblies, whether physical or digital.

Link: Aalborg University Press

http://aauforlag.dk/…/arkitektur-design…/bricks-systems.aspx

Link: Aalborg University Research Portal

http://vbn.aau.dk/…/bricks–systems(ba86e77d-44dd-4761-8aab…

 

SEMINAR: CAMBRIDGE UNIVERSITY, BETTER URBAN FORMS

On Monday 12th of December, I will be giving a talk on “Better Urban Forms” at the Department of Engineering, Cambridge University, UK.

MEDIA: COLLABORATION SAO PAULO UNIVERSITY

Our collaboration with Prof. Pauletti from Sao Paulo University is in its second year. We are happy that the impact of this collaboration is discussed on the PU homepage 

TedX: Form Follows Force

TEDX: Next Saturday I am presenting my “Idea Worth Spreading.” at George School, PA. By 2050, 70% of the world’s population will live in cities. Structural engineers envision, design and construct the bridges and long‐span buildings those city dwellers depend on daily. The construction industry is one of most resource‐intensive sectors, and yet our urban continues to be built in the massive tradition in which strength is pursued through material mass. In contrast, I have focused my research on structural systems that derive their strength from their curved shape, dictated by the flow of forces. As a result, these structures can be extremely thin, cost‐effective, and have a smaller carbon footprint.

 

 

MEDIA: Resilient, Smart Cities

Our work on resilient, smart, livable cities is featured in “Discovery Research at Princeton”. Read more about it here

“Like forms in nature, engineering professor Sigrid Adriaenssens’s structures often show striking curves, from spiraling earthen walls and arching steel footbridges, to shell-shaped pavilions that keep out direct sunlight while admitting scattered light and breezes.” Bennet McIntosh

LECTURE: FORM, MATERIALS AND SHELLS

Join us to celebrate the launch of the exhibition entitled: Timber Gridshells: Architecture, Structure and Craft. The private view of the exhibition directly follows on from a free guest lecture delivered by Professor Sigrid Adriaenssens from Princeton University (USA) entitled FORM, MATERIALS and SHELLS at 6pm Pennine Lecture Theatre, Level 2, Sheffield Hallam University S1 1WB right across the road from Millennium Gallery. November 4th 2016.

image credit: Prof. I. Lochner

LECTURE: HOW FORM MATTERS

Please join us at Kent State University, this Thursday for an exciting lecture on “How form matters” at the new Center for Architecture + Environmental Design and the Cleveland Urban Design Collaborative! 5h30pm Cene Lecture Hall

INAUGURAL RECEPTION: SPIRALING DIRT

Spiraling Dirt. (June 2016)

This rammed earth spiral is entirely made out of local, Princeton soil. It revisits a traditional vernacular construction technique used in New Jersey in the 19th century, and throughout the past 3 millennia around the globe. Rammed earth deserves renewed attention because of its sustainable potential as a low-cost zero-emission material. Local soil, coated with a lime-dirt mixture for erosion protection was densely compacted into a temporary wooden formwork. The spiral’s performance over time will be monitored as an ongoing Campus as a Lab research project of the Form Finding Lab in the Civil and Environmental Engineering Department.

Designed by Tim Michiels and Prof. Sigrid Adriaenssens.

Construction lead by Tim Michiels (earth construction) and Eric Teitelbaum (carpentry) with a construction team consisting of Amber Lin, Jacob Essig, Victor Charpentier, Sigrid Adriaenssens, Olek Niewiarowski and Paul, Steve and Mike from the Princeton University Civil Engineering and Construction crew

FUNDING: Princeton University Resilient City Lab

Cities are centers for innovation and offer economic and social opportunities.  They are complex, dynamic metasystems where technical, economic and social networks intersect.  Because the vulnerability of these intersecting systems cannot be completely predicted, cities are also hot spots for disasters caused by climate change, energy scarcity, growing urban populations and manmade and natural catastrophes. In the face of this unpredictability, we want cities to be resilient and able to prepare, respond to and recover from significant multi‐hazard threats with a minimum of damage to public safety, health, economy and security.  Under uncommon stress, people and property have proven to fare better in resilient cities.   The research goal of this proposal is to develop a community-level framework for studying extreme event scenarios in cities taking into account infrastructure and social dependencies.

BOOK CHAPTER: Model Perspectives

We are delighted with the publication of our contribution “Nervi’s isostatically inspired ribbed floors” in Cruvellier’s and Sandaker brand new book on Structure, Architecture and Culture. The book is described as a “treasure trove”.  We cannot wait to read it!

PRESENTATION: A seismic analysis of Félix Candela’s Church of our Lady of the Miraculous Medal

T. Michiels; M. Garlock; T. Huyn, and S. Adriaenssens.   ‘A seismic analysis of Félix Candela’s Church of our Lady of the Miraculous Medal’, in 10th International Conference on Structural Analysis of Historical Constructions, Leuven, Belgium, 2016.

FUNDING: 2017 ICFNJ Undergraduate Research

Congrats to Amber who secured funding for her project on “Rammed Earth and erosion protection measures” from ICFNJ!

BOOK: ADVANCED ARCHITECTURAL GEOMETRY 2016

The Advances in Architectural Geometry (AAG) symposia serve as a unique forum where developments in the design, analysis and fabrication of building geometry are presented. With participation of both academics and professionals, each symposium aims to gather and present practical work and theoretical research that responds to contemporary design challenges and expands the opportunities for architectural form.

The fifth edition of the AAG symposia was hosted by the National Centre for Competence in Research Digital Fabrication at ETH Zurich, Switzerland, in September 2016.

This book contains the proceedings from the AAG2016 conference and offers detailed insight into current and novel geometrical developments in architecture. The 22 diverse, peer-reviewed papers present cutting-edge innovations in the fields of mathematics, computer graphics, software design, structural engineering, and the design and construction of architecture.

Get it here for free

CONFERENCE: AAG2016

I am getting ready for the AAG2016 Conference in Zurich where I will be chairing a very exciting structural session.The AAG 2016 conference brings together researchers  to present and discuss the challenges  emerging at the intersection between geometry and design.

http://www.aag2016.ch/

BLOG: FROM STUTTGART TO RIO, SBP STADIUM DESIGNER KNUT STOCKHUSEN

With the Olympic Games in full swing, we can but marvel at the lightweight elegant roofs covering some of the stadia.  We spoke with Knut Stockhusen (sbp) who designed and built a number of them.

FUNDING: Grand Challenges project – Novel Deployable Storm Surge Protection for Coastal Cities

We are really delighted to have been awarded by the Princeton Environmental Institute (PEI) – Grand Challenge for our research proposal. Together with Prof. Ning Lin (Hurrican Hazards and Risk Analysis Group, CEE, PU)  we will develop stowable storm surge protection systems for use in coastal cities.

BLOG: A FREE FORM IN RIO

If you are in Rio, do not miss out on checking out the “Carioca Wave” freeform! /

BLOG: A New Design for the Tokyo 2020 Olympic Stadium

Though Japan has selected Kengo Kuma’s design over Zaha Hadid’s for its 2020 Olympic Stadium, how can we envision the structure from a form-finding point of view? Our students have come up with three proposals, one of which has been selected as a finalist in IASS 2016’s Design Competition for the Young Generation. check out our blog

PRIZE: NATIONAL STADIUM FOR JAPAN IDEA COMPETITION DESIGN

Congratulations to our grad students Mauricio Loyola Vergara and  Alexander Niewiarowski who are amongst the winners of the IASS 2016 National Stadium for Japan competition.  Their “mountainous grid shell” design started in the CEE546 Form Finding of Structural Surfaces class.  A well deserved honor!

PRESENTATION: Revisiting the form finding techniques of Sergio Musmeci: the Bridge over the Basento River

S. Adriaenssens, S. Gabriele, P. Magrone and V. Varano  ‘Revisiting the form finding techniques of Sergio Musmeci: the Bridge over the Basento River.’ in ICSA 2016, Guimares, Portugal, 2016.

BLOG: CONSTRUCTION OF A SWIRLING RAMMED EARTH WALL

Find out how we constructed a swirling rammed earth wall this summer!

MEDIA MENTION: TRANSFORMATIONS

“This project really energized me to be a maker and a doer and physically create something. I couldn’t be more thankful to the class for allowing me to create something like this.”

Wonderful feature on Princeton University’s webpage on a class that explores the intersection of engineering and the arts, co-taught by Prof. Adriaenssens last spring! The class will be offered again this spring.

Picture: From left, students Noah Fishman, Nora Bradley and Sunny He prepare a device they designed that allows visually impaired people to experience color.

BLOG: A DELIGHTFULLY SWEET PAVILION

We anticipate Belgium National Day  by sharing one of our projects on designing and constructing a chocolate pavilion! Delicious– in more ways than one

MEDIA MENTION: NATURE DOES IT BETTER

“Nature is lazy and intelligent– it uses very little material and places it in the right place.” We were happy to contribute to this article on biomimicry in architecture!

LECTURE: FLEXIBLE SHELLS

Our graduate student Victor Charpentier ’18, is presenting his work on Flexible Shells at Pedro Reis’s EGS lab at MIT on 6th of July.

PUBLICATION: DESIGN-TO-CONSTRUCTION WORKFLOW FOR CELL-BASED PATTERN RECIPROCAL FREE FORM STRUCTURES

Reciprocal structures are composed of mutually supporting rigid elements that are short with respect to the span of the entire structure. Although reciprocal structural systems have received significant interest among architects and engineers, they are not yet commonly employed in construction. The main reason for this non-adoption, is the complexity of conceiving a structure from a module to the global scale without adapting the structure’s final global shape. As a result, two approaches have emerged for the design of reciprocal structures. The first approach takes the module as primary building blocks and the final global form emerges as a result of the module’s properties. The second approach results from adjusting the module’s properties throughout the surface of the structure to fit its predefined global shape. This paper presents a complete design-to-construction workflow for reciprocal frames using a cell-based pattern algorithm. The developed parametric model explores geometry and patterning to adapt any module geometry to any free-form surface by adjusting the eccentricities between the modules. The resulting reciprocal structure is then analyzed and sized using finite elements. Finally, manufacturing layouts are generated and construction processes are discussed. The design-to-construction workflow was validated experimentally with the construction of a 5-meter diameter reciprocal hemispherical dome.

Y. Anastas, L. Rhode-Barbarigos, and S. Adriaenssens ‘Design-to-Construction workflow for cell-based pattern reciprocal free-form structures‘ , Journal of the International Association of Shell and Spatial Structures, vol. 56(2), pp. 159 – 176, 2016

BLOG: Reflective practitioner and educator

How to practice and teach well? Demi Fang ’17 asked Eric Hines and received some thought-provoking answers.  Read about their conversation in our blog

AWARD: WALBRIDGE GRADUATE AWARD

Congrats to Victor ’18 on winning the Walbridge Graduate Award!

MEDIA MENTION: Digging into service at Forbes

Eight PACE Center Interns enjoyed working with Amber Lin and Tim Michiels on our rammed earth project.  Read there story here

LECTURE: STRUCTURAL AFFAIRS

On Monday 13th of June, I will be presenting our work on form active, passive and adaptive structures to the Master Graduate Architecture Students at Sao Paulo University, Brazil. I further look forward to review their work on deployable roofs together with Prof. Ruy Pauletti (USP) and ing. Knut Stockhusen (SBP).

CONGRATS TO THE CLASS OF 2016: AVETE ATQUE VALETE

Congrats to the graduating class of 2016! Lu Lu, Dennis Smith, Russell Archer and Aaron Katz, it was a pleasure advising your thesis! Avete atque valete. (Catullus) (I salute you and … goodbye)

BLOG POST: DO UTILITARIAN SILOS HAVE ESTHETIC VALUE?

Can structures, designed solely for functional purposes, be esthetic? Le Corbusier seemed to think so. Read this week’s blog post

Image credit: Malmo Cement Silo, PUL Ingenieure Catalogue

PRIZE: AARON KATZ ’16 WINS CEE BOOK AWARD

Aaron Katz’16, won the CEE Book Award for his senior thesis “An evaluation of the earthquake loading capacity of rammed earth walls.” This award is given to a senior in the CEE department who has written an outstanding senior thesis. Congratulations, Aaron! Find out more about Aaron’s work here 

RECEPTION: COSTA SURFACE

To celebrate the learning achieved in the CEE graduate course “Non-linear analysis of pre-stressed structural systems” this semester, visiting Professor Ruy Pauletti from University of São Paulo and myself would like to organize a small event.  The grad students will showcase and discuss the Costa Surface Sculpture  they designed, calculated and built.  Friday 20th May 4-5pm in the CEE Student Lounge (opposite the school office). 

 

image credit: Prof. R. Pauletti

BLOG POST: HOW TO NUMERICALLY MODEL A COSTA SURFACE?

Our grad students explored different form finding techniques to establish the form of the fascinating Costa surface, a surface with no boundaries and intersections with itself. Read more about that in our blog post here

image credit: math.hmc.edu

 

BLOG POST: MAKING BUILDINGS BREATH

During my Art Residency  in Bellagio, Italy, I had the privilege of interviewing USC Architecture Professor and Princeton alumna Doris Kim Sung. In her work, Doris interprets architecture as an extension of the body and explores how buildings can passively adapt to their environment through self-ventilation and shading by using smart materials and design.

Read my interview with her here

THORNTON TOMASETTI STUDENT INNOVATION FELLOWSHIP: TIM MICHIELS

I am very pleased to announce that PhD candidate Tim Michiels has won the THORNTON TOMASETTI STUDENT INNOVATION FELLOWSHIP for innovative research concerning finding forms for earthquake resistant zero-carbon shell structures made from earth using a dynamic relaxation algorithm. Congratulations, Tim!

BLOG POST: BENDING ACTIVE SYSTEMS IN ANTIQUITY

Find out what was so special in the bow of Odysseus in our latest blog post https://formfindinglab.wordpress.com/2016/05/04/strain-energy-the-bow-of-odysseus/

PUBLICATION: STRUCTURAL DELIGHTS: COMPUTATION, MATTER AND THE IMAGINATION

This article records an asynchronous discussion conducted via email over the course of several weeks. Initiated by Martin Bechthold, the co-authors were invited to contribute sequential responses in the course of a virtual conversation centered on questions of design, engineering, computation and materials.

M. Bechthold, S. Adriaenssens, P. Michalatos, N. Oxman and A. Trummer ‘Structural Delights: Computation, Matter and the Imagination’, GAM 12 Architectural Magazine, vol. 12, pp. 32-55, 2016.

ROCKEFELLER ART RESIDENCY: SURROGATE TREES

Together with Artist Doris Kim Sung and Environmental Engineer Russell Fortmeyer (ARUP) I will be thinking about and designing surrogate tree systems for natural tree depleted urban environments  in Bellagio, Italy (May 2nd – May 10th). This is such a great opportunity to take our work on biomimetic systems to an urban scale.

 

Image: Bloom by Doris Kim Sung

MoMA SYMPOSIUM: Structured Lineages: Learning from Japanese Structural Design

The event Structured Lineages: Learning from Japanese Structural Design will be held on Saturday April 30th 8.30am-4.30pm at MoMA. 
Reserve your seat here

This event runs in conjunction with the exhibition A Japanese Constellation: Toyo Ito, SANAA, and Beyond and is organized by The Museum of Modern Art and Guy Nordenson of Princeton University, with John Ochsendorf of MIT. Speakers and panelists include William Baker of SOM Chicago; Seng Kuan of Washington University; Marc Mimram, architect and engineer, Paris; Laurent Ney of Ney + Partners, Brussels; Mike Schlaich of Schlaich Bergermann Partner, Berlin; and Jane Wernick of Jane Wernick Associates, London. Additional panelists include Sigrid Adriaenssens of Princeton University; Caitlin Mueller of MIT; and Mutsuro Sasaki of SAP, Tokyo; with concluding remarks by Martino Stierli, The Philip Johnson Chief Curator of Architecture and Design.

Image: St Mary Cathedral, Tokyo, Tange and Tsuboi collaboration

BLOG POST: COSTA SURFACE NO BOUNDARY AND NO INTERSECTION WITH ITSELF

How to visualize and realize a finite surface with no boundary and no intersection with itself?
Find out more on this week’s blog post https://formfindinglab.wordpress.com/2016/04/28/a-physical-costa-surface-13-history-of-the-surface/

DISCUSSION: ENGINEERING AND CREATIVITY

You are invited to a fascinating discussion on “Engineering and Creativity” between 4 of the world leading structural designers Mike Schlaich, Laurent Ney, Marc Mimram and Mutsuri Sasaki here on Campus.  The event takes place this Monday 2nd of May Betts Auditorium (School of Architecture) 11.30 AM – 1PM. The conversation will be led by our own students Olek Niewiarowski, Sharon Xu and Aaron Yin.

Image: bridge studio Mimram

SCHOLARSHIP:Princeton Energy & Climate Scholar: Tim Michiels

Founded in 2008, Princeton Energy and Climate Scholars (PECS) brings together a select group of highly talented and engaged Princeton Ph.D. students with research expertise ranging from energy security and technology to climate science and policy.

PECS enhances the research experience of Princeton’s graduate students by encouraging them to transcend the boundaries of their fields and by fostering a sense of common intellectual adventure. Drawing from a broad range of disciplines, PECS students and members of the Faculty Board thoughtfully approach multifaceted energy challenges of the 21st century.

LECTURE AND WORKSHOP: RETRACTABLE ROOFS SBP

Some of the iconic lightweight roofs you will see hovering above the Summer Olympic Games in Brazil this summer, were designed by Knut Stockhusen and his team.  Knut, Partner and Managing Director of world renowned schlaich bergermann partner practice, also happens to be the lead structural designer of the stadia designed for the 2014 FIFA World Cup in Brazil, the legendary Maracanã Stadium, in Rio de Janeiro, and the Arena da Amazônia, in Manaus. He has been actively engaged in international projects since 2000, and managed several FIFA and UEFA Stadia projects.

Knut and his team are amongst leading experts in the field of lightweight structures with a particular focus on sports venues and stadium design. He has accumulated a wealth of experience in the design, analysis and construction of moveable structures and retractable roofs. In this lunchtime talk he will focus onto this particular type of systems.

His engineering prowess has been celebrated by a number of awards for pioneering engineering projects such as the National Stadium Warsaw, and the stadia designed for the 2014 FIFA World Cup in Brazil, the Maracanã Stadium, in Rio de Janeiro, and the Arena da Amazônia, in Manaus.

He graduated from the University of Stuttgart in 1999 and currently leads projects for the 2022 FIFA World Cup Qatar, and other projects in Europe and South America. Knut is a member of the Chamber of Engineers Baden-Württemberg and International Association for Shells and Spatial Structures.

OUTREACH: YOUNG WOMEN’S CONFERENCE STEM

The Young Women’s Conference in Science, Technology, Engineering, and Mathematics introduces middle-school and high-school aged girls (in 7th though 10th grades) to women scientists and engineers and the wide breadth of careers available to them in these fields. Prominent female scientists and engineers from around the region spend the day with the girls in a variety of formats that includes small-group presentations, hands-on activities, a keynote address, and tours of laboratories.

LAUNCH FORM FINDING LAB: BLOG AND FACEBOOK PAGE

https://www.facebook.com/formfindinglab/

https://formfindinglab.wordpress.com/

MEDIA: PU WEBPAGE FEATURES “EXTRAORDINARY PROCESSES”

Tension mounted at the Lewis Center for the Arts‘ Lucas Gallery as Julia Wilcots, a civil and environmental engineering major at Princeton, hung small sandbags from the graceful wood bridge that spanned the gallery’s clean white walls.

The bridge — thin strips of ash crossed in an X and mounted at their four ends — bowed and shimmied with each new weight. Its stresses and deflections seemed to transmit directly into the intently watching students gathered for the final session of “Extraordinary Processes,” a seminar offered jointly by theProgram in Visual Arts and the Department of Civil and Environmental Engineering.

Having succeeded in meeting the course requirement of loading the bridge with 16 pounds, Wilcots and fellow student Neeta Patel tried radically shifting all the weight to one end, and Wilcots could not bring herself to fully release her hand from the last weight as the asymmetrical structure danced near the edge of its stability.

“Go for it,” said Patel, a senior majoring in Program 2 studio arts in the Department of Art and Archaeology and Wilcots’ partner in making the bridge.

“I love it,” said Joe Scanlan, director of the Program in Visual Arts who co-taught the class this fall. “The artist is saying ‘Let go!'”

It was the sort of moment that Scanlan and his collaborator Sigrid Adriaenssens, assistant professor of civil and environmental engineering, had hoped for as they invented a course to nudge students beyond their comfort zones at the boundary of art and engineering. The two began talking a couple years ago about teaching a class together and looked for a theme that appealed to both of them and was not grounded specifically in either art or engineering.

An environmental crisis provided the impetus they needed: the recent decimation of ash trees by an invasive insect, the emerald ash borer. First discovered in Michigan in 2002, the insect’s destruction of ash trees has spread across the Eastern United States, reaching New Jersey in 2014. With tens of millions of trees lost, ash lumber is temporarily plentiful. As Scanlan and Adriaenssens researched ash and its plight, the more intrigued they became.

“It wasn’t any old tree,” Scanlan said. “It was the wood that made the 20th-century leisure culture — tennis racquets, picnic baskets, canoe paddles. It has a lot of interesting structural properties — you can work with it really thin as a veneer, you can work with heavy pieces, and it’s very amenable to steam-bending.”

During the semester, the students heard talks by experts engaged in the ash tree crisis and visited the studios of legendary woodworker George Nakashima in New Hope, Pennsylvania. They built their own apparatus to steam-bend wood, a process of exposing wood to high-temperature steam until it becomes pliable, and conducted lab sessions that explored the difference between mathematical predictions and actual experience. They made self-portraits out of ash and culminated the semester with the bridge project.

The title “Extraordinary Processes” came from the idea that “extreme amounts of invested time and manual labor are capable of transforming the ordinary into the extraordinary,” according to the course description.

“To work with one material so intensively for one semester is really enriching,” Adriaenssens said. Immersed in cutting, carving, bending, weaving, buckling and simply handling the ash wood, the students’ creativity grew.

“Their bridges show systems that I haven’t really seen before,” Adriaenssens said. “They were really playing with it.”

At first, the two professors noted that the students’ approaches to the class were firmly rooted in their respective disciplines. “Arts students bristled at the measuring and utility that was woven into the class,” Scanlan said. “Engineers were dubious about discussions of aesthetics.”

As the semester progressed, however, arts students developed forceful ideas about utility and engineers were appreciating the aesthetic success that is possible even in something that failed a structural test.

“In the end there was not so much a split — here is an engineer and here is an artist,” Adriaenssens said. “The boundaries softened and the two had really merged.”

One group made a looping chain of veneer-thin strips bent into figure eights and fastened with a combination of rivets and embroidery thread. Their first challenge had been making the strips. “The more we did it, the better we got at making a consistent thickness,” said Veronica Nicholson, a senior majoring in Program 2 studio arts in art and archaeology, as she hung fruits to weight the bridge during the class demonstration.

“Then we were surprised by how strong and versatile the loops were,” said her teammate Lu Lu, a senior majoring in civil and environmental engineering.

With the strips in hand, the group did not make detailed drawings or calculations beforehand like those in traditional bridge design. “The process was very tactile,” Lu said. “It was respecting and exploring specific properties and potentials of the material, instead of focusing on a drawing which might hinder that process.”

Michael Cox, a junior majoring in civil and environmental engineering, said it was the first class he’s had that not only focused almost entirely on hands-on problem solving but also incorporated an aesthetic viewpoint. “It is really interesting having both Joe and Sigrid’s perspectives,” he said.

He built a bridge with seniors Olivia Adechi, who is concentrating in Spanish and Portuguese languages and cultures, and Lauren Frost, who is concentrating in Program 1 history of art in the Department of Art and Archaeology. The team wanted their bridge to compress horizontally like an accordion when loaded. Adriaenssens helped them think about a system of hinges and a pulley-like arrangement of strings that pulled their structure sideways. But Scanlan suggested turning the whole plane of the mechanism from vertical to horizontal.

“It was a suggestion that would only come from the two perspectives combined,” Cox said.

In the end, their bridge consisted of two arms, each made of four hinged segments, that crossed the gallery in a large horizontal polygon. The weights pulled segments closer, while others moved apart. “It was spectacular how it moved,” Adriaenssens said.

 

written by Steven Schultz

FUNDING: CAMPUS AS A LAB

Princeton earth zero carbon structures : Dirt—as in clay, gravel, sand, silt, soil, loam, mud—is everywhere. The ground we walk on and grow crops in also happens to be one of the most widely used construction material worldwide . Earth does not generate CO2 emissions in its generation, transport, assembly or recycling and this in contrast to more conventional building materials such as concrete and steel. In rammed earth construction a mixture of suitable loam, clay and sand is compressed into a formwork to create a solid low-cost loadbearing wall. Despite the renewed architectural interest in contemporary rammed earth construction in (semi-)arid climates of the USA, little is known about its potential in the erosive humid continental climate of New Jersey. Therefore we propose a multi-faceted rammed earth exploration in Princeton University Forbes garden through the construction and monitoring of a set of walls and a pavilion made out of local soil.

 

EXHIBITION: EXTRAORDINARY PROCESSES

The MEDIA STUDIES exhibit features sculptures crafted from ash wood by students in VIS 418 / CEE 418: Extraordinary Processes. Co-taught by Joe Scanlan (Director, Princeton Visual Arts Program) & Sigrid Adriaenssens (Professor of Civil & Environmental Engineering), the class explored the structural and artistic possibilities of this material, which is in abundant supply owing to the spread of an invasive insect, the emerald ash borer (Agrilus planipennis). These artworks highlight ash’s strength and its flexibility, transforming the gallery with their structures and casting beautiful shadows …

PUBLICATION: An Automated Robust Design Methodology for Suspended Structures’

Suspended structures such as cable roofs and bridges are tensile spatial systems. The objective of this paper is to describe an automated robust design methodology that can be used to evaluate suspended structures. Numerical simulations combine dynamic relaxation for the nonlinear structural analysis with a non-dominated sorting genetic algorithm (NSGA-II) for multicriteria optimization. The formulation used is general and adaptable to allow for handling of multiple objectives and constraints concurrently. Robust designs are obtained by including random uncertainties in the methodology. Uncertainties are assigned to model inputs which yields outputs with associated uncertainties. Polynomial chaos expansion (PCE) is utilized to create reduced-order stochastic structural analysis models. These models allow statistical robust measures to be obtained with reasonable computational time. A polyester-rope suspended footbridge case study is analyzed to show how the methodology handles both static and dynamic parameters. Test cases in which Young’s Modulus and prestress are taken as random variables are examined. Two objectives (maximization of the lowest in-plane natural frequency and minimization of rope volume) and two static constraints (maximum stress and maximum slope) are considered simultaneously. Best compromise solution sets, also named Pareto fronts, for the deterministic and robust designs are compared and found to be similar for all test cases examined. Thus, for this case study, the deterministic solution is the most robust solution. The design methodology described in this paper can be used to evaluate other suspended systems subject to different constraints, objectives, uncertainties, etc. Consequently, this methodology has the potential to be a powerful computational tool for designing robust suspended structures.

E. Segal, L. Rhode-Barbarigos, R. Coelho, and S. Adriaenssens, ‘An Automated Robust Design Methodology for Suspended Structures’, Journal of the International Association of Shell and Spatial Structures, vol. 56, pp. 221-229, no.4, 2015

PRESENTATION: SUSTAINABLE AGENDA

On Thursday 19th November, I will be presenting our work on Sustainable Structural Forms in the Sustainable Agenda’s Symposium, Princeton University, School of Architecture, 5pm.

PUBLICATIONS: Learning Form Finding and Flexible Shells

Large displacements and the stiffness of a flexible shell

The design of static thin shell structures can be carried out using analytical and numerical approaches. Recently, thin shells have been studied for their flexibility, which can be beneficial for adaptive systems. However flexible systems involve large displacements and precise kinematics. The analysis of flexible shell systems is challenging due to the nonlinearities induced by these large displacements. This study addresses the nonlinear behaviour and stress-stiffening effects caused by large displacements in a 0.80 m-long carbon fibre reinforced plastic shell consisting of two monolithically connected lobes. The structural behaviour of this system is investigated both numerically and experimentally. Following the analysis
framework, the non-linear effects of the large displacements on the shell stiffness are numerically determined using eigenvalue analysis and the displacement response to external loading on deformed shell configurations. The numerical displacement results are compared with results obtained in the experimental study. In conclusion, our study shows that the stiffness of the shell system under study increases 113% during deformation. More precisely, we establish that this change in stiffness is governed by the presence of tensile stresses in the shell surface due to deployment rather than by the change of the system’s geometry.

A project-based approach to learning of structural surfaces

In the last two decades, a renewed interest has arisen, both from the structural engineering and architectural field, to exploit the elegance and structural efficiency of structural surfaces. This paper discusses a project based course aimed at graduate architecture and civil engineering students to i) develop an in-depth understanding of the basics of surface structures, ii)
cultivate relevant numerical and physical form finding proficiency, iii) communicate complex technical issues with peers and iv) problem scope, brainstorm and generate design alternatives for force-modeled systems. Because of the nature of the course and workshop objectives, the evaluation of the effectiveness is qualitative rather than quantitative. Therefore, the findings
are supported by students’ reactions captured in their course evaluations as well as their chosen careers paths after graduation. Since there is rarely room for the introduction of new courses in an established academic curricula, this paper also shows how the course can be adapted to project-based workshops which can vary in length from half of a day to three days. In conclusion, this paper is of interest to educators in structural engineering and architecture because it contributes to methods for effectively teaching structural surface structures.

PUBLICATION: Innovative structural bridge typologies

Bringing together historic and contemporary case studies, our chapter discusses the influence of form finding, optimization and digital fabrication techniques on the development of novel bridge typologies.  First, we discuss the engineering and societal framework within which these methods are introduced and present a succinct overview of recent computational advances in the domain.  Second, we focus on design case studies of prominent bridges that highlight the evolution in structural typologies that these design tools have facilitated.  We distinguish two series. The first series are form found bridges, characterized by their three-dimensional composition of linear elements. The second series of optimized typologies explores the potential of surface elements, facilitated through digital fabrication techniques.  Finally, we emphasize the role of the bridge designer and suggest how these tools can aid in the discovery of novel efficient bridge typologies.

S. Adriaenssens*ᵻ and A. Boegle, ‘Digital design and fabrication techniques facilitate novel bridge typologies’, in Innovative Bridge Design Handbook: Design, Construction and Maintenance’, 1st ed., A. Pipinato, Ed. Chennai: Elsevier, 2015.

PRESENTATION AND SESSION: Advances in Dynamic Relaxation

At Structural Membranes 2015 (Barcelona, Spain,19-21 September) , we will be chairing a session and presenting our latest work on the form finding method, dynamic relaxation. In particular we will focus on the capabilities of the torsion/beam element algorithm and different damping approaches.

KEYNOTE: STRUCTURAL FORM FINDING AND OPTIMIZATION

At the SPP 1542 Jahrestreffen 2015, in Bochum, Germany I presented our research on form active, passive and adaptive structures. At the same time we explored how to connect the hand to the mind while generating hanging physical models and inverting them as shells.

FEATURE: ‘Motion and mirrors put light to work in buildings’

Civil engineers typically spend a lot of effort securing structures in place, but Sigrid Adriaenssens is finding new possibilities in motion. “If we allow structures to move, we can do some very interesting things with them,” said Adriaenssens, an assistant professor of civil and environmental engineering. Specifically, Adriaenssens is interested in elastic deformation – the ability of a structure to deform in response to a force and then return to its original shape once the force is removed. One of her newest projects involves creating a folding shade on the outside of buildings. The shade would open and close as the sun strikes the structure’s surface – illuminating and darkening the interior as needed. “It would be a beautiful feature that helps define the architecture,” she said. “But it would also be a component that would be very useful for the building.” Working with Axel Kilian, an assistant professor of architecture, Adriaenssens is developing a thin structure assembled around bi-metallic beams. When sunlight heats a beam, it expands the two metal components at different rates, causing the beam to flex. By carefully calculating the shape of the cells between the beams, the researchers can build a shade that opens and closes using only the sun’s energy. “If we change the thickness of the material, the shape of the cells and other components, we can create completely different structures,” she said. The sunshade project, with its unusual but innovative perspective, is the type of work that is often difficult to support through traditional funding. Adriaenssens has funded the research through the Andlinger Innovation Fund, which is administered by the Andlinger Center for Energy and the Environment and is intended to promote cross-disciplinary collaborations outside traditional funding systems. “The approach of combining structures, forms and materials for environmental and structural performance is new, and it can be difficult to fit into traditional funding models,” Adriaenssens said. “The grants make it possible to undertake a new kind of research.”

n another unusual project, Adriaenssens and Kilian are teaming up with Adam Finkelstein, a computer science professor, to create a simple reflector to draw daylight into offices. The researchers hope that the work, supported by the University’s Wilke Family Fund, could someday substantially decrease the amount of energy used for lighting a building. They call the reflector a light shelf. It is simple in concept, but quite complex to pull off. The shelf not only needs to draw light into a variety of shapes and orientations, it also needs to be cheap enough to deploy in large numbers of windows. “It is a reflective surface that mounts on a window,” Adriaenssens said. “The shelf can be made up of very small areas and each is oriented in such a way that they maximize the amount of light reflected into a room.” Experts estimate that 14 percent of electricity usage is related to interior lighting and that the amount is up to 60 percent higher in office buildings. “With this device, we can reduce that usage by 20 to 60 percent depending on the location,” said Adriaenssens, who added that the researchers hope to have a prototype in about a year. “The ultimate goal is to produce a simple device that could reduce energy consumption, particularly in large office buildings.” Another critical application will be designing the many small structures that make up the shelf with an eye to maximizing the amount of light reflected inside. Finkelstein, a specialist in computer graphics, said it is like focusing an array of tiny mirrors to produce a beam of light. “The idea is to redirect light coming from the sun to bounce off the ceiling the same way that light fixtures do,” he said. “It’s hard to make a reflector that works optimally for any orientation of window, at any latitude, at any time of the year and at any time of the day. So part of the goal of the project is to think about how to design a reflector that would do a reasonable job across different times of day and times of the year and that can be customized for a particular location.”

by John Sullivan

IStructE STREAM SPEAKER: Innovate, create and inspire

The Institution of Structural Engineers hosted an International Conference on the third and fourth of September 2015, at The Grand Hyatt Hotel, Singapore. The event saw international delegates discuss structural engineers’ global role, the future challenges faced by the profession, and the key priorities for structural engineering education. As an invited speaker, I presented our work on compressive and tensile structures.

NSF AWARD: Adaptive Building Skin to Enhance Interior of Buildings

Operating buildings, for either professional or residential use, accounts for as much as 41% of the energy consumption in the United States of America. Adaptive building skins are active filters between the interior environment and outside weather conditions. These skins are able to respond to changing outdoor weather conditions and indoor operational needs, potentially reducing the energy demand of a building by as much as 51%. However, current adaptive building skins rely on mechanical hinges and actuation devices of high construction complexity and life cycle cost. These attributes are obstacles to their broader adoption. Therefore, this award supports the fundamental research underlying the development of lighter, more durable, and, mechanically, less complex adaptive skins. More energy efficient buildings will lead to decreased greenhouse gas emissions, less US dependency on fossil fuels, and improved well-being of individuals in society. For this project, a team spanning the disciplines of civil and mechanical engineering, material science and botany is assembled. This project will have a broad educational impact through the curating of an exhibition at a national museum and providing research experiences at high school, undergraduate and graduate levels and outreach to the K-12 community.

 

TSUBOI AWARD AND PRESENTATIONS: SHELLS, ACTIVE LEARNING, BIOMIMETIC TOPOLOGIES AND MUSMECI

Lochner-Aldinger, Karl, J. Adriaenssens, S.(2015). ‘Biomimetic approach to structural morphology.’ IASS Symposium: Future Visions, Amsterdam, Netherlands.

Fang, D; Adriaenssens, S; Bands, H; Segal, E. (2015). ‘The digital engineering classroom: collaborative structural design space and supplementary educational material.‘ IASS Symposium: Future Visions, Amsterdam, Netherlands.

Adriaenssens, S; Schmidt, K., Katz., A., Gabriele, S., Magrone, P., Varano, V. (2015). ‘Early Form Finding Techniques of Sergio Muscemi revisited. ‘IASS Symposium: Future Visions, Amsterdam, Netherlands.

Michiels, T; Adriaenssens, S; Rhode-Barbarigos, L. (2015).‘Topology Optimization of a cylindrical thin shell subjected to the 1992 Landers earthquake’ IASS Symposium: Future Visions, Amsterdam, Netherlands.

Charpentier, V; Adriaenssens, S; Rhode-Barbarigos, L; Baverel, O. (2015). “The influence of large displacements on the stiffness of an adaptive shell.” IASS Symposium: Future Visions, Amsterdam, Netherlands.

Adriaenssens, S. (2015). ‘Learning “Form Finding of Structural Surfaces”: an effective project-based course’. IASS Symposium: Future Visions, Amsterdam, Netherlands.

AWARD: AFFORDABLE, SUSTAINABLE INFRASTRUCTURE FOR EMERGING MEGACITIES

Energy consumption is a global strategic issue. With more than 50% of the human population living in growing urban areas, improving building-energy efficiency is a major challenge. The building sector accounts for approximately 40% of the world’s energy consumption and associated carbon dioxide (CO2) emissions. According to the US Energy Information Administration, the US building sector uses approximately 40% of the primary energy. Fossil fuels account for 75% of this energy, largely due to the energy required during construction phases.
Comparable to the US, Brazil’s building sector accounts for 45% of the national energy consumption. However, the challenges on the road to a sustainable built environment are different for both countries due to their social-economical context. For example, the Brazilian per-capita income is 1/5 of the USA. Additionally, Brazil is facing the challenge of the rising megacities which experience explosive growth and income disparity. Sustainable, material-intensive approaches and technologies developed for the North cannot be successful in Brazil. Therefore, we seek to build a collaborative program around affordable, sustainable megacity infrastructure that will focus on innovative, material-efficient strategies for the design of an urban environment, informed by its social-economic context. If successful, these strategies will reduce energy consumption and C02 emissions, and also improve housing and living conditions in the megacity.
The objectives of this project are (i) to reinforce existing endeavors that deepen the intellectual engagement between Princeton and São Paulo University,  (ii) to progress the existing body of knowledge on affordable sustainable construction and (iii) to prepare for continued collaborative teaching and research beyond this grant.

PUBLICATION: Conceptual Design of a Single-Crease Origami-Arc Inspired Movable Footbridge Structure

Origami, the craft of folding paper, has been a source of inspiration for developable foldable systems in various engineering disciplines. Origami inspired segmented plate systems result in lightweight and stiff structures that change shape by folding. With curved-crease origami, a three-dimensional change in shape can arise from a single fold mechanism. In this paper, the curvedcrease mechanism of a single-crease arc is investigated as the driver for the conceptual design of a movable footbridge. The folding mechanism is investigated using particle-spring models and small-scale physical models. The structural feasibility of a 40 m radius curved-crease origami-inspired movable footbridge is investigated using finite element analysis. Static analysis and sizing according to US footbridge design code are presented for the critical configurations of the footbridge. Results show that the footbridge can meet typical civil engineering design criteria and illustrate the potential of curved crease folding mechanisms to inspire the development of movable structures.

PUBLICATION: DETAIL ENGINEERING 4: SOM

With nearly 80 years of experience in integrating architecture and engineering, Skidmore, Owings & Merrill’s (SOM) work remains groundbreaking, especially when it comes to designing supertalls. Besides addressing the question of “how high can you go”, as well as the issues of efficiency and economy, this fourth volume of the DETAIL engineering series presents the theoretical background of SOM’s structural group. On the basis of a variety of projects with their general structural concept or their specific details, the book explains the process of finding corresponding solutions. These solutions illustrate the company’s core values: simplicity, clarity, hierarchy, efficiency and continuous research. I contributed to this edition by writing about the importance of hierarchy at different levels in their work and compared it to structural poetry.

PUBLICATION:Dialectic Form Finding of Structurally Integrated Adaptive Structures

Structural engineering, prompted by advances in mechanics
and computing as well as design principles such as sustainability and
resilience, is evolving towards adaptive structures. Adaptive structures
are structures that use active components to change shape and
properties in response to their environment and/or to their users’
desires. Form-found structures, such as tensegrity and shell structures,
can be designed to accommodate such changes within their structural
behavior. Dialectic form finding is an extension of the traditional
form-finding process integrating performance-related constraints and
criteria in the search of a geometry in static equilibrium. Two
examples of dialectic form-found structurally integrated adaptive
structures are presented. The first example is a shape-shifting
tensegrity-inspired structure, while the second example is a shapeshifting
shell structure. Both systems are designed to explore elastic
deformations for shape changes reducing actuation requirements and
highlighting the potential of the proposed method.

TSUBOI AWARD: best conference paper in IASS 2014, Brasilia

Our paper “An automated robust design methodology for suspended structures”. has been selected as the winner of the IASS Tsuboi Award in the category of the most outstanding paper in the Proceedings of the 2014 IASS-SLTE Symposium, Brasília, Brasil.  The Tsuboi Award honors the memory of Professor Yoshikatsu Tsuboi (Japan, 1907-1990), former President and Honorary Member of the IASS, and his outstanding contributions to structural and architectural design. The authors are Ted Segal, Landolf Rhode-Barbarigos, Rajan Coelho and Sigrid Adriaenssens.

AWARDED: Rockefeller Foundation Bellagio Center Residency

The goal of the residency is to explore, discuss, contemplate, develop andpropose tangible ways to make artificial, surrogate trees for urban environments where real trees are limited or lacking. The intent is to develop a resilient infrastructure that is
cost-effective, zero-energy, easy to maintain, and highly performative. In addition shading, cooling, and filtering the air below, the new structures can propose places for activity, community and identity. The infrastructure can be a new canvas for artists and expression; it can house performances or spawn new types of performances; and, it can even be made into an instrument to make music. These new urban pockets can embody the merging of art with science, and serve the community on multiple levels.

CONGRATULATIONS TO HANNAH!

Hannah Bands received her Master Degree! Congratulations, Hannah!

PUBLICATION: MULTI-OBJECTIVE OPTIMIZATION OF POLYESTER-ROPE AND STEEL-ROPE SUSPENDED FOOTBRIDGES

Historically, suspended footbridges have been built from ropes (i.e., cables) constructed of a variety of
materials including iron and natural fibers. However, contemporary suspended footbridges are typically
constructed with steel rope. One exception, a 64 m span polyester-rope footbridge completed in 2013,
demonstrates the potential for alternative rope materials in contemporary footbridge design and construction.
The first goal of this paper is to support the idea that polyester rope has promise in future footbridge
applications by comparing minimum rope volume and self-weight results for polyester-rope and
steel-rope footbridges with spans ranging from 15 to 64 m in two multi-objective optimization problems.
In both problems the competitive objective functions are span which is maximized and rope volume
which is minimized. The results are minimum volume systems for spans in the defined range.
Minimizing volume reduces rope cost and eases material transport and handling. To provide an alternative
measure of rope quantity, volume results are scaled to find the equivalent self-weights. This study
focuses on in-plane structural behavior and investigates two-dimensional rope systems with or without
prestress and with or without under-deck stays. A combination of static and natural frequency constraints
is considered in the optimization problems. The second goal of this paper is to describe the novel
methodology developed to evaluate these optimization problems. This methodology combines a
non-dominated sorting genetic algorithm for searching the design space with dynamic relaxation and
eigenanalysis algorithms for the structural analysis. Results indicate that polyester-rope systems have
higher volumes, but lower self-weights than steel-rope systems. This observation supports the premise
that polyester-rope footbridges are potential alternatives to steel-rope footbridges. The presented
methodology can be adapted to evaluate how other unconventional materials compare to more conventional
counterparts that are well established in bridge applications.

TALK: “Taut Structures:  a personal approach to the analysis of cable and membrane structures”

In the presentation, the challenges for the form finding and analysis of taut, light and flexible structures will be discussed.  A number of techniques such as Newton’s method, matrix methods, the force density (and its extension natural force density) as well as dynamic relaxation will be highlighted and exemplified with a number of design examples.

Please join us on Wednesday 3rd of June at 4:30pm in E219, CEE, PU for Prof. Pauletti, Sao Paulo University on ““Taut Structures:  a personal approach to the analysis of cable and membrane structures”.

CONGRATULATIONS TO TED SEGAL!

Congratulations to Ted for obtaining his PhD today!

AWARD FOR MICHAEL: DAVID CARMICHAEL PRIZE AND GEORGE J. MUELLER AWARD

Congratulations to Michael Manhard for winning these two awards. The first one is awarded in CEE for his outstanding thesis in civil engineering. The second one celebrates his academic achievements with quality performance in intercollegiate athletics.

AWARD FOR DENISA: CEE BOOK AWARD and MAC CRACKEN SENIOR THESIS AWARD

Congratulations to Denisa for winning both prizes – one at the departmental and one at the School level – for her senior thesis that is most distinctive for its inventiveness and technical accomplishment.

AWARD: ALFRED RHEINSTEIN ’11 AWARD

Alfred Rheinstein was a civil engineer and builder noted for developing low-cost housing projects in the NYC area. He graduated with a civil engineering degree in 1911 from Princeton University.  In his honor,Prof. Adriaenssens plans to spend award toward the study of low-cost, forced-modeled, shell structures made of low strength waste materials. The forms of these shells, will be form-found and optimized for earthquake loading and other extreme loads. Not only do these shells show great potential to be aesthetically pleasing and economically efficient, but also provide the community effective shelters in times of natural disaster.

TALK: BISTABLE SHELL STRUCTURES

My talk will consider some of the ways that it is possible to make a shell structure bistable, i.e. where the structure can be left unloaded in two different configurations.  In particular I will consider structures have the same initial geometry as a simple tape-measure; they are straight in a longitudinal direction, but have a curved cross-section.  However, unlike a tape-measure, the structures have a stable coiled configuration.  Structures using this technology are already being used as coilable masts, and have been suggested for use as components of aircraft landing gear.

Two different methods of making these shells bistable will be described.  The first depends on altering the relative bending stiffnesses of the shell using, for instance, fibre-reinforced composites.  The second requires an initial state of self-stress to be set up in the shell.  Physical examples of both types of structure will be available to show the wide range of behaviour that is possible.

A simple inextensional analytical model that captures the key properties of the shells will be descibed.  An interesting prediction of the model is that it is possible to make tubes that are neutrally stable; they have no stiffness, even for large deformations.  An example will be shown.

Princeton Homepage: Denisa’s adaptive origami structure

Princeton  student Denisa Buzatu’s vision for an environmentally sustainable building is a sort of shape-shifting origami façade. For her senior thesis, Buzatu, is designing and prototyping a structure that shades the façade of a building by folding and adapting its shape in response to sunlight.

Her design takes advantage of a type of wire that contracts when current is applied to it and yet “remembers” and returns to its original shape. These wires make up the edges of eight triangular faces, which are combined to form a seamless surface, and can be activated individually or in combination by a microcontroller to fold the surface in myriad ways.

PUBLICATION:Robust topology optimization of truss structures with random loading and material properties: A multiobjective perspective

In this paper an approach to robust topology optimization for truss structures with material and loading uncertainties, and discrete design variables, is investigated. Uncertainties on the loading, and spatially correlated material stiffness, are included in the problem formulation, taking truss element length into account. A more realistic random field representation of the material uncertainties is achieved, compared to classical scalar random variable approaches. A multiobjective approach is used to generate Pareto optimal solutions showing how the mean and standard deviation of the compliance can be considered as separate objectives, avoiding the need for an arbitrary combination factor.

Richardson, J.N., Coelho, R.F., Adriaenssens, S. (2015).‘Robust topology optimization of truss-like structures with random loading and material properties: a multi-objective perspective.’ In: Computers and Structures doi:10.1016/j.compstruc.2015.03.011

TALK AND WORKSHOP: The beauty of lightweight structures

In the framework for the Princeton-Sao Paolo strategic partnership, I have been invited by Prof. R. Pauletti to present our research and give a workshop on physical modeling of membrane structures in collaboration with Eng. Knut Stockhusen from Schlaich Bergerman and Partners. 4-5 April at the Civil Engineering Building of Sao Paolo University.

PRESENTATION: ASCE CONGRESS 2015 Portland

Lightweight suspended footbridges are frequently constructed in rural areas. Often, contemporary structures of this type utilize steel cables, but the completion of a 64m span polyester-rope bridge in 2013 demonstrates the potential of a non-traditional material for this application. In this presentation, design strategies for polyester-rope suspended footbridges are described. These strategies highlight the influence of low material stiffness and high damping (determined through full-scale bridge testing) on the static and dynamic behavior of polyester-rope bridges.  Modifications to structural performance are achieved by adjusting rope prestress, adding supplemental mass to the bridge, and/or including under-deck stiffening ropes.  The effects of these changes on form and construction are discussed.

This presentation will be of interest to practitioners, researchers, and academic members in structural and architectural engineering because of its focus on a material that is new to suspended footbridge design. The strategies presented may aid a design professional if a site lends itself to a polyester-rope suspended footbridge. Researchers may see opportunities to develop optimization routines that can refine the strategies and forms presented.

SCHOLARSHIP: THORNTON TOMASETTI for Denisa BUZATU

Denisa Buzatu has been chosen to receive the Thornton Tomasetti Foundation National 2015-2016 Scholarship for her exceptional academic success and demonstrated interest in the integration of engineering and architecture. Well done, Denisa!

FINAL PUBLIC ORAL EXAM: Ted Segal Characterisation of polyester-rope suspended Footbridges

On May 1st Ted will be defending his PhD work on Characterisation of polyester-rope suspended footbridges.  This event will take place in E219 at 12h30pm.  You are invited to attend.

FUNDING: COURSE EXTRAORDINARY PROCESSES CEE418/VIS418

Since 2002, the emerald ash bore beetle, Agrilus planipennis, has destroyed more than 20 million ash trees in the US, with only 30% of the waste timber recycled into low-end products such as mulch and firewood. High value uses could turn this “waste” material into a valuable resource and an economic opportunity, especially considering that, before the widespread development of plastics, aluminum, and carbon fiber, the high tensile strength of ash wood was optimal for fabrication and use in the form of vehicle undercarriages, industrial infrastructure, and sporting goods. The ash bore beetle only established itself in New Jersey, a state with 24.7 million imperiled ash trees, in Spring 2014. The movement of ash wood is currently under federal and state quarantine. Our course “Extraordinary Processes” will adopt new ways of thinking about and finding novel uses for local infested ash wood as a catastrophically available material. The course will also develop learning opportunities beyond the “chalk and talk” classroom and explore hands-on synergies between engineering and the arts.

TALK: FORM FINDING AT ARUP

Henry Unterreiner, Ecole des Ponts, Paris will share his work on the form finding of the New Mexico Airport, MOMA PS2 Mushroom Tower and Park on the Hudson River.  All be welcome! March 17th, 2015 2-3pm E219

WORKSHOP: REVISITING MUSCEMI at Università Roma Tre

In this workshop the students will learn to apply physical and numerical FORM FINDING techniques for the shape generation of form-active (pre-stressed membranes) and form passive (thin shell structures) systems. Using these tools, the students will develop a research-by-design project that draws its inspiration from the masterworks of Sergio Musmeci (Rome, 1926-1981). The projects will be showcased and critiqued in the Scientific Seminar Session at the School of Architecture, Università Roma Tre 14-17 april 2015.

http://host.uniroma3.it/laboratori/lams/FFW

TALK: SHELLS REVISITED – Learning from the Gothic Master Builders

This lecture will present new computational form-finding and optimization approaches for exploring three-dimensional equilibrium shell structures, based on the stability analysis of the Gothic masonry vaults. Thanks to the intuitive graphical methods, the designer gains control over the exploration of form, which allows designing vaults with little or low-quality materials, or designing efficient and expressive surface structures. Several projects will demonstrate the power of these innovative methods for the safety assessment of historic masonry vaults with complex geometries and for the design and engineering of novel masonry shells, which range from sustainable construction solutions for developing countries to unique unreinforced vaults in tile or cut stone. The last part of the lecture will demonstrate how we can learn from the Master Builders to design better – well beyond masonry.

TALK: How a historian and a civil engineer look at landscape and infrastructure.

In context of the Princeton-Mellon Initiative Urban Studies Research Seminar at Princeton, Sigrid Adriaenssens and Vera Candiani will be showcasing how practitioners from different disciplines interrogate components of our built and unbuilt environments. This will be an interactive and experimental pedagogical practicum designed for undergraduate and graduate students, part of our effort to demonstrate how to work collaboratively and in closer engagement across disciplines to unpack what surrounds us. All are welcome.N-107, March 13, 2015, 12-13:30

PUBLICATION: A unified stochastic framework for robust topology optimization of continuum and truss-like structures.

In this article, a unified framework is introduced for robust structural topology optimization for 2D and 3D continuum and truss problems. The uncertain material parameters are modelled using a spatially correlated random field which is discretized using the Karhunen–Loève expansion. The spectral stochastic finite element method is used, with a polynomial chaos expansion to propagate uncertainties in the material characteristics to the response quantities. In continuum structures, either 2D or 3D random fields are modelled across the structural domain, while representation of the material uncertainties in linear truss elements is achieved by expanding 1D random fields along the length of the elements. Several examples demonstrate the method on both 2D and 3D continuum and truss structures, showing that this common framework provides an interesting insight into robustness versus optimality for the test problems considered.

TALK: Embodied computation and models of design

The relationship between design intent and the possibilities of new models of design possible through computation creates interesting challenges about the embodiment of design. Embodied computation can be understood as the steering of form in the design process as well as the implementation of a design idea into a physical construct that continues to adapt during its lifetime. Examples of both instances will be shown from structural form finding, actuated towers and concept car studies.

TALK: CREATING AN INCLUSIVE CLASSROOM

How do you design your classes to enable all of your students to succeed? Students arrive at University from a wide spectrum of intellectual and social experiences that may unevenly prepare them for coursework across the curriculum. Furthermore, students may begin your class with a conception of themselves as inherently capable of flourishing in some disciplines but not in others, a mindset which might limit their academic success. We all know students who say they are “not math people” and we see others quietly disengage from a risky discussion of ambiguities in a text. This lunchtime discussion opens a conversation to share how we view the range of our students’ academic strengths and how we can surface their tacit learning preferences. Whatever differences our students bring to us, then, how might we encourage all of our students to discover their potential for intellectual dexterity and engagement in an academic setting? What diverse paths to learning can we design for coursework and class meetings?

NSA shell on cover of IASS Journal

Read more about the actual form finding of the shell  in Adriaenssens S., Ney L., Bodarwe E., Williams C., (2012). ‘Construction Constraints drive the form finding of an irregular meshed steel and glass shell’. In: Journal of Architectural Engineering. 18(3) ,pp.206-213,doi: 10.1061/(ASCE)AE.1943-5568.0000074

In the context of the search for an efficient structural shape to cover the Dutch Maritime Museum courtyard in Amsterdam, Netherlands, the authors briefly discuss the driving design factors that influenced the earliest glass roof coverings. The trends that emerged during the late 20th and early 21st century in the design of skeletal steel glass shells are exposed. These design developments range from sculptural to geometric and structural intentions. The discussion of the competition design development of the Dutch Maritime Museum steel glass shell roof shows the quest for a structurally efficient catenary form based on a poetic geometric idea. This paper presents a construction-driven design methodology that slightly adapts the numerical form found catenary shape with the objective of achieving planarity in all the triangulated, four-sided and five-sided mesh faces. The challenge of facet planarity is gracefully solved by an analytical origami approach and presented. This approach is compared with finding the Maxwell reciprocal network diagram. The final faceted shape shows elegance and structural efficiency.

 

 

 

 

PUBLICATION: Form finding and analysis of inflatable dams using dynamic relaxation

Inflatable dams are flexible membrane structures inflated by air and/or water. Due to their ease of construction, rapid deployability and low cost, these systems have great potential for hazard mitigation applications in the context of global warming. However, designing inflatable dams is a challenging task as the dam’s initial equilibrium shape has to be determined by either experimental or numerical form-finding methods. Furthermore, the dam’s shape and the applied loading are coupled since changes in the form of the structure induce also changes in the loading profile. In this paper, dynamic relaxation, a well-established form-finding and analysis technique, is employed for the cross-sectional analysis of inflatable dams. Using this technique and the proposed extensions, the structural behavior of inflatable dams can be analyzed under constant and varying internal pressure as well as different loading and support conditions. The results are in agreement with published results in literature. Therefore, the presented method provides an alternative computationally advantageous tool for the design of inflatable dams

PUBLICATION: Nonlinear Elastic In-Plane Buckling of Shallow Truss Arches

The available analytical methods for determining the buckling resistance of trusses typically focus on the local load capacity of individual elements and ignore global in-plane buckling behavior. In addition, theoretical expressions that describe the in-plane critical buckling load of shallow arches do not account for trusses or nonsolid cross sections. This paper investigates the nonlinear elastic in-plane buckling behavior of shallow truss arches subjected to a uniformly distributed gravity load. Adapted methods for calculating the equivalent moment of inertia and equivalent area of truss cross sections are presented first. Using these equivalent geometric properties and existing analytical expressions, a novel methodology is then presented for generating an equivalent arch model that accurately predicts the critical nonlinear elastic inplane buckling behavior of shallow truss arches. This methodology is validated by obtaining close agreement between the nonlinear elastic critical buckling factors of the truss arches and their accompanying equivalent arch models. Approximation equations, using the equivalent moment of inertia, are also generated for estimating the nonlinear elastic critical buckling factor for fixed- and pin-connected shallow truss arches. A simple strategy is presented to augment the existing nonlinear elastic in-plane arch buckling equations by efficiently identifying the approximate central axis location of the truss cross section at midspan.

 

PUBLICATION: In-plane optimization of truss arch footbridges using serviceability and stability objective functions

This paper investigates the use of stability and serviceability objective functions in the shape optimization of truss arch footbridges prone to in-plane snap-through buckling. The objective functions evaluated relate to global linear buckling, geometrically nonlinear response, fundamental frequency, linear compliance, and maximum deflection. These objective functions are applied to help define the global structural shape for the 2D configuration of a truss arch footbridge subjected to its governing code-defined load combination. The strength criterion of maximum axial force, the global stability responses of critical linear buckling load and nonlinear limit load, and the serviceability responses of fundamental frequency and unfactored live load deflection are used to evaluate the optimized topologies. These structural performance results are compared to those of a benchmark structure prone to in-plane snap-through buckling. The results highlight that improvement in stability and serviceability behavior can be obtained by altering the global structural form according to the presented objective functions. Stable optimized topologies, which are not prone to in-plane snapthough buckling, are achieved without the use of computationally expensive, geometrically nonlinear analysis functions.

 

FUNDING: DAYLIGHT HARVESTING THROUGH GEOMETRIC BUILT FORM

75% of all electricity produced in U.S. is expended in the construction and operation of buildings. Of that energy, 14.4% is typically devoted to fluorescent or incandescent lighting. However, in commercial buildings, this percentage can be as much as 60%. On Princeton University’s campus, we have identified at least 14 buildings (being E‐Quad, Bowen, Friend, Comp Sci, Wallace, Corwin, Fisher, Arch, Woolworth, McCosh, Gyot, Powers Field, Fine and Peyton) that use Venetian blinds to reduce solar gain and glare. Unfortunately, these blinds fail to redirect lighting into the office space. As a result, we switch on incandescent or fluorescent lighting in our offices, classrooms and labs throughout the day. In contrast, daylight harvesting uses daylight to offset the amount of electric lighting required to adequately light a space which can reduce the energy consumption between 20‐60% . Recent research in computer graphics and architecture has focused on the potential of caustics, the bundling or diverting of light rays by reflection and refraction of a surface, to esthetically enhance the quality of spaces. We propose to draw on these recent developments and advance them through development into a design methodology for campus‐specific daylight harvesting systems. Our research goal is to investigate how lighting and structural performance can be integrated into a single, daylight harvesting surface that reduces the operational energy consumption of a typical campus building.

 

FUNDING: Spatial Adaptable Rapidly Erectable Building Systems

At a time of increased awareness about sustainability globally, adaptive building systems could provide the needed resources minimising solutions. The aim ofthe new partnership is to establish research synergy and understand the regional trends and capability, especially with the new partners from USA. Therefore the main activities, two one week workshops (USA and Korea) and final conference (Denmark), aim to create a platform for global k nowledge and data sharing, enabling the participants to determine the specific interests of the other i nternational researchers, their current progress, sharing views on global research issues in the field. The network will give possibilities for exploring: a) early stages researchers’ mobility, b) new-shared graduate teaching courses, and, c) joint funding applications including additional industrial partners from Asia, Europe and USA. The two workshops (USA and Korea) will present the state-of-art research work within Europe, Asia and USA, and also, generate new research links between Europe, Asia and Denmark. The visits will give input into the research partners’ current work, facilities, their networks, and also establish links with other researchers from these environments. The common conference held in Denmark towards the end will build a discussion platform and establish future collaboration agreements beyond the current network program.