Sigrid Adriaenssens « Form Finding Lab

JOURNAL PUBLICATION: Integration of kinks and creases enables tunable folding in meta-ribbons

You can read about our important work on the mechanics of kinks and creases now in Matter. Free downloads here https://lnkd.in/eNu48a5G

Highlights
•The nonlinear folding behaviors of annular ribbons are comprehensively investigated
•The folding mechanism and bifurcation type of elastic annular ribbons are uncovered
•The meta-ribbon is created by integrating in-plane kinks and out-of-plane creases
•The tunable dynamic folding behavior of a meta-ribbon is achieved

Progress and potential
Exploring how thin structures fold can lead to innovative technologies in fields like soft robotics, flexible electronics, and space deployable systems. By studying the mechanics of folding in elastic ribbons, through discrete model, theory, and experiment, we uncovered that different types of folds, i.e., in-plane kinks and out-of-plane creases, initiate folding in distinct ways and correspond to different types of bifurcation. We also found that by combining these folds strategically, we can create “meta-ribbons,” which can fold smoothly or abruptly based on how they are engineered. This tunability opens doors for advantages like controllable dynamic folding and transitions among different stable states, offering exciting possibilities for future technologies.

EXHIBITION: SWARM GARDEN

Our recent “Swarm Garden” exhibition, a collaboration with Princeton University’s Nagpal research group, showcased how swarm intelligence and adaptive mechanical designs can create “living-like” environments. At the Lewis Arts Complex’s Co_Lab, visitors experienced firsthand the blend of art and engineering, witnessing how these dynamic spaces promote health and happiness.

HONOR: FRANCQUI CHAIR AND INTER UTRUMQUE MEDAL

Prof. A was awarded the 2024 Francqui Chair at Ghent University, Belgium. The Francqui Foundation promotes excellence in fundamental research by fostering higher education and scientific advancement in Belgium. She also received the medal of Ghent University “Inter Utrumque” (which means between science and humanities).

AWARD: GRAND GOLD ‘I LIVE WITH NATURE’

The ‘I Live with Nature’ garden has won the Grand Gold Award, the highest award available, at the 2024 Greater Bay Area Flower Show in Shenzen, China. The show garden, designed by Jo Thompson, includes our intricate brick pavilion at its center created using Augmented Reality technology and self-balancing mechanics without any site survey, construction drawings or in-person training of the Chinese-only speaking contractor. We designed, analyzed and determined the construction of the pavilion is less than 3 months. This project underscores the Form Finding’s Lab commitment to integrating innovative technology with natural and urban environments.

RESEARCH FUNDING: HMEI BUILDING FOR BIODIVERSITY

The built environment causes major land fragmentation and habitat loss through construction and raw material extraction. However, sustenance and growth of animal populations and diversity can be enhanced through urban master planning, engineered designs of wildlife infrastructure, and adoption of low carbon construction practices. Current master planning and engineering design are mainly focused on efficiency, economy and elegance, all human centric requirements. The goal of this project is to present the first animal-informed urban planning and infrastructure design methodology that generates and enhances bio-diverse habitats and passages based on circular economy principles. The research testbed is the rapidly changing environment of the Princeton University campus and its surroundings. Given that Princeton is endowed with a diversity of animal species, and the area will continue to develop, the site makes a perfect microcosm to study how design can impact biodiversity. This project will identify mammal species that indicate broader biodiversity, will research and test animal-informed suburban planning and infrastructure design, document their use, and raise public awareness of the enhanced campus biodiversity. Princeton can protect its natural endowment by fostering biodiversity as a primary ethic in development and design, setting an example for suburban spaces where human and non-human animals co-exist.

JOURNAL PUBLICATION: Kirigami-inspired wind steering for natural ventilation

Ensuring adequate ventilation of exterior and interior urban spaces is essential for the safety and comfort of inhabitants. Here, we examine how angled features can steer wind into areas with stagnant air, promoting natural ventilation. Using Large Eddy Simulations (LES) and wind tunnel experiments with particle image velocimetry (PIV) measurements, we first examine how louvers, located at the top of a box enclosed on four sides, can improve ventilation in the presence of incoming wind. By varying louver scale, geometry, and angle, we identify a geometric regime wherein louvers capture free-stream air to create sweeping interior flow structures, increasing the Air Exchange Rate (ACH) significantly above that for an equivalent box with an open top. We then show that non-homogeneous louver orientations enhance ventilation, accommodating winds from opposing directions, and address the generalization to taller structures. Finally, we demonstrate the feasibility of replacing louvers with lattice-cut kirigami (“cut paper”), which forms angled chutes when stretched in one direction, and could provide a mechanically preferable solution for adaptive ventilation. Our findings for this idealized system may inform the design of retrofits for urban structures – e.g. canopies above street canyons, and “streeteries” or parklets – capable of promoting ventilation, while simultaneously providing shade.

WORKSHOP: SEGOVIA 2024 WEAR YOUR WEAVE

We explored the mechanics of woven networks for the design and making of a dynamic and static human scale performance piece. This workshop at the IE University was organized by Prof. Wesam Al- Asali and brought together architecture students and the amazing basket weaver Carlos Fontales-Ortiz. Together, we explored how bending, buckling, stretch and drape in rod networks coupled with traditional basket weaving techniques can produce installations that can perform when loaded. The workshop culminated in an interesting performance at the Creativity Center at the IE University in Segovia, a UNESCO World Heritage City, Spain.

JOURNAL PUBLICATION: novel graphical assessment approach for compressed curved structures under vertical loading

Important research developed for the Angelus Novus project.

JOURNAL PUBLICATION: Continuous Stress-Based Form Finding

Excited to share this publication developed for the design of the award-winning Angekus Novus vault!

JOURNAL PUBLICATION: Experimental and Numerical Characterization of a Rotational Kirigami System

Engineered kirigami strategies enable structural systems that reduce cost and energy through flat-packing and rapid assembly. We studied the effect of the polygonal shape and cut pattern on the structural behavior of rotational kirigami units under tension and compression loads. Multi-step finite element models were developed, compared to experiments, and shown to predict experimental results robustly in the decimeter scale. We evaluate buckling-to-deployment load ratios, showing the load-carrying capacity of the system, and present a sensitivity analysis on localized geometric imperfections. These verified models can be used to further develop the system for load-carrying applications at larger scales.

AWARD: VENICE BIENNALE ECC INNOVATION

Inspired by Brunelleschi’s dome of the Santa Maria del Fiore and Klee’s artwork Angelus Novus, the Form Finding Lab and the UCHV Research Film Studio of Princeton University, together with architects and engineers at Skidmore, Owings & Merrill, present an exhibition that explores new possibilities for the self-balancing vault—a construction method that has enabled centuries of architectural innovation. In the garden of Palazzo Mora, the Angelus Novus Collaborative displays a self-balancing masonry vault constructed using augmented reality (AR), and a digital film-fresco that is viewable in two ways: on an LED panel, and on the vault itself via an interactive AR application.

Ph.D. position available (ML, circular economy, structural design)

Would you like to join my research group the Form Finding Lab in the Department of Civil and Environmental Engineering at Princeton University as a PhD student? Are you keen on delving into machine learning approaches and circular economy principles to transform the structural engineering design framework? If you have a background in any of those fields, you are strongly encouraged to apply to this Ph.D. position.
You can officially apply via Princeton University’s application portal (https://lnkd.in/e2k8Cmga) by January 3, 11:59 pm EST. For instructions and qualifications, you can consult the department’s guidelines https://lnkd.in/efJErrhm).

If you are seriously interested in joining my group, do not email me since I am on sabbatical. But send me a handwritten letter and a printed CV. The letter should explain why and how you will make a good fit for the position and can be sent to
Prof. Sigrid Adriaenssens
E332 E Wing
Engineering Quadrangle
Princeton University
Princeton NJ 08544
USA

2023 Myron Goldsmith Visiting Chair at IIT College of Architecture

I am thrilled to have been asked to be the 2023 Myron Goldsmith Visiting Chair at IIT College of Architecture (Chicago, IL).
If I could go back to the 60’s, I wish I could be part of Myron’s ‘Saturday Sessions’, reviews at IIT, followed by a lengthy lunch at Bertucci (I learned this is one of the ways he infused practice and education). My mentor David Billington always lauded Myron and I have studied him in the context of his work with Fazlur Khan. (At Princeton we organized a studio course and exhibition on Fazlur Khan.) As a bridge designer, I have always found joy in the stay geometry of the Ruck A Chucky bridge which turns out to be of the hand of Myron. I am honored to be sharing my structural design insights and experiences in this capacity with the students and amazing Chicago-based designers and to present the Form Finding Lab work at IIT.

PROCTER FELLOWSHIP FOR EDVARD BRUUN

Congrats to my PhD student Edvard Bruun, on being awarded the Procter Fellowship. This prestigious honorific fellowship reflects the Princeton University Graduate School’s exceptionally high opinion of his scholarship.

FUNDING: PU SEAS Innovation: Kirigami tailors airflow and shade in public, outdoor spaces

In urban environments facing rising temperatures, pollutants, and airborne viruses, we need spaces that can thermally regulate and effectively ventilate, all with minimal energy input. To address the needs for shade and ventilation in cities simultaneously, we propose a solution based on kirigami, the ancient Japanese art of paper cutting. Adding cuts to a thin sheet frees pore-like sections to buckle out-of-plane and rotate when the sheet is stretched in one direction. This mechanism could be used to steer wind into spaces with stagnant air to improve air filtration,while also modulating sunlight to improve thermal comfort, thus reducing energy needs for cooling. Kirigami offers a widely customizable, zero-waste design, which is easy to deploy and adaptively actuate. The aim of this research is to develop a framework for designing kirgami structures that can be tuned to optimize shading, ventilation, or a combination of the two.

INTERNATIONAL WOMEN’S DAY

Celebrating the engineering achievements of the wonderful women in my research group, the Form Finding Lab, and all those I was lucky to work with over the years!

USC PRESENTATION: FORM AND FORCE IN THE URBAN ENVIRONMENT

I was delighted to present our work in the 2023 Engaged Spring Series Lecture in the School of Architecture at the University of Southern California – Los Angeles, and learn about their adaptive re-use studios.

EXHIBITION: BALANCING ACT

Newton’s laws of motion lie at the basis of the works shown in this exhibition. A body is in equilibrium when it balances out external forces acting on it with the internal forces within. Even when this equilibrium is disturbed like by pulling and releasing a node in a net, this equilibrium is restored, and the node returns to its initial position. The works on concern networks comprised of many interconnected flexible, semi-flexible or rigid elements. The way in which the individual elements are connected (i.e, .their topology) and the collective shape they constitute, determine how the global network responds to external loading. This exhibition is structured in three parts. The first part focuses on efficient equilibrium shapes for tensile nets and inverted compressive nets with linear elements. The second part introduces shape-shifting flexible networks that are metastable and inspired by the handcraft of lace. The third part focuses on how domes and vaults, composed of rigid volumetric elements, can be assembled without any external supports.

14 E Peace St, Raleigh, NC 27605

31 January -24 February 2023

A big shout out to NC State University and the AIA Triangle for their support.

Poster Design: Axel Larsson

PNAS PUBLICATION: Continuous modeling of creased annuli with tunable bistable and looping behaviors

Creases are purposely introduced to thin structures for designing deployable origami, artistic geometries, and functional structures with tunable nonlinear mechanics. Modeling the mechanics of creased structures is challenging because creases introduce geometric discontinuity and often have complex mechanical responses due to local material damage. In this work, we propose a continuous description of the sharp geometry of creases and apply it to the study of creased annuli, made by introducing radial creases to annular strips with the creases annealed to behave elastically. We find that creased annuli have generic bistability and can be folded into various compact shapes, depending on the crease pattern and the overcurvature of the flat annulus. We use a regularized Dirac delta function (RDDF) to describe the geometry of a crease, with the finite spike of the RDDF capturing the localized curvature.Together with anisotropic rod theory, we solve the nonlinear mechanics of creased annuli, with its stability determined by the standard conjugate point test. We find excellent agreement between precision tabletop models, numerical predictions from our analytical framework, and modeling results from finite element simulations. We further show that by varying the rest curvature of the thin strip, dynamic switches between different states of creased annuli can be achieved, which could inspire the design of deployable and morphable structures. We believe that our smooth description of discontinuous geometries will benefit the mechanical modeling and design of a wide spectrum of engineering structures that embrace geometric and material discontinuities.

www.pnas.org/doi/10.1073/pnas.2209048120

JOURNAL PUBLICATION: CREATIVE TENSION HOW A CHOREOGRAPHER AND AN ENGINEER INNOVATE TOGETHER

This month’s A+U edition focuses on Engineering Art. I am proud as punch to see our work with the choreographer Rebecca Lazier featured in it. Other contributors to the edition include Mike Schlaich and Anne Burghartz, John Ochsendorf, Mark Sarkisian, Bill Baker and Alessandro Beghini, Guy Nordenson, Walter Hood, Walker Downey and Caroline A. Jones, Adam Weinberg

WE MADE IT ON THE COVER OF EXTREME MECHANICS!

Happy Holidays from the Form Finding Lab! Enjoy our Origami Water Bomb Curved Crease Studies on the Cover of this month Extreme Mechanics. Do they do not look a little like ornaments or snowflakes?

JOURNAL PUBLICATION: Effect of crease curvature on the bistability of the origami waterbomb base

Largely due to its geometry-endowed bistability, the origami waterbomb base offers wide-ranging engineering potential. Here, we explore how nonzero crease curvature, which leads to panel bending, enhances the tunability of this structure. To reveal the influence of crease curvature on the deployed geometry and the mechanical response of the octagonal curved-crease waterbomb base, we combine physical experiments with a parametric numerical study. The crease curvature ranges from zero (i.e. the well-known straight-crease waterbomb base) to the maximum curvature possible within the allotted boundary. In addition, we perform finite element analysis (FEA), which incorporates crease plasticity and also allows us to examine the effects of crease stiffness and sheet thickness on mechanical behavior. Our results show that increasing crease curvature reduces the folded height and vertex range-of-motion, but raises the critical load for snap-through instability, without necessarily increasing the switching energy. Applications for these tunable structures can range from small-scale, energy harvesting mechanical metamaterials, to architectural scale adaptive shading devices and large-scale deployable space-based solar power systems.

JOURNAL PUBLICATION: Learning the nonlinear dynamics of mechanical metamaterials with graph networks

The dynamics of soft mechanical metamaterials provides opportunities for many exciting engineering applications. Previous works have shown tremendous success in describing the unique nonlinear dynamics of certain types of soft mechanical metamaterials. However, capturing the nonlinear dynamic response of these materials especially those with complex geometries, can be a challenge due to the strong nonlinearity and large computational cost. An efficient and reliable framework to predict the overall response of the metamaterials based on the geometry of their building blocks is not only key to understanding the unique behavior of metamaterials, but also vital to the rational design of such materials. In this work, we propose metamaterial graph network (MGN), a machine learning approach to address this challenge. MGN is based on a graph that represents the lattice-like metamaterial structure. The trained MGN is capable of simulating the dynamics of a metamaterial structure with over 200 by 200 unit cells, a task that is practically impossible for traditional direct numerical simulation using the finite element method. We also verify the accuracy of the proposed MGN against several representative numerical examples. In the first two examples, we show that MGN successfully captures the well-known pattern transformation behavior of porous metamaterials. In the later examples, we consider wave propagation in a dynamic setting and show that MGN produces quantitatively accurate results compared with direct numerical simulation. An additional feature of MGN is that defects/inhomogeneities can be easily incorporated into the metamaterial structure. We expect our method to open a new avenue for the study and modeling of mechanical metamaterials.

FUNDING: PIIRS Structural Crafts: Developing Vernacular Construction for Sustainable Futures.

We are delighted to deepen and enrich our understanding of Spain-based craft construction using natural locally available materials with this new funding. We look forward to working with Dr. Wesam Al Asali, School of Architecture, IE University.

JOURNAL PUBLICATION: Differential Formulation and Numerical Solution for Elastic Arches with Variable Curvature and Tapered Cross-Section

In this paper, an alternative analytical and numerical formulation is presented for the solution of a system of static and kinematic ordinary differential equations for curved beams. The formulation is represented here as being useful in the structural evaluation of arch structures and it is propaedeutic to be used in optimization frameworks. Using a finite-difference method, this approach enables the evaluation of the best solution sets accounting for (1) various arch shapes (i.e. circular, quadratic and quartic polynomial forms); (2) different loading combinations; (3) cross-sections varying along the arch span; and (4) different global radius of arch curvature. The presented original approach based on finite-difference, produces solutions with a good precision in a reasonable computational time. This method is applied to 4 different arch case studies with varying rise, cross-section, loading and boundary conditions. Results show good agreement with those obtained using a numerical finite element approach. The presented approach is useful for the (preliminary) design of arches, a common and efficient structural typology for road and railway bridges and large span roofs. As far as buckling verifications are concerned, the comparisons in terms of maximum acting axial force and critical axial force computed is reported in order to consider the effect of instability phenomena coming to trace for each arch configuration the feasible domain.

JOURNAL PUBLICATION:

The Impact of Online STEM Teaching and Learning During COVID-19 on Underrepresented Students’ Self-Efficacy and Motivation

Female students, students of color, first-generation students, and low income students face considerable barriers in access to STEM education, leading to their underrepresentation in STEM fields. Ensuring that these students develop strong self-efficacy and motivation in STEM during the college years is key to addressing the “leaky” STEM pipeline. To determine whether the rapid shift to online teaching and learning during the COVID-19 pandemic exacerbated or mitigated inequities for college-level STEM students, we examined correlations between demographic and sociocultural factors and students’ self-assessments on indicators of self-efficacy and motivation. Our findings suggest that students from underrepresented groups were differentially negatively impacted by the shift to online teaching and learning, particularly with regard to access to study spaces, the internet, and peers. However, we found that the loss of traditional laboratories was not particularly impactful on any students’ motivation or self-efficacy, regardless of a course’s levels of dependence on such labs, as students were generally more impacted by concerns about family members’ health and loss of social and structural supports than academic experiences. We discuss these results in light of psychosocial theory and suggest pedagogical and structural changes that can support more equitable outcomes in online and in-person college-level STEM education.

MEDIA: COMPOSERS AND COMPUTERS

GRADUATION: AVE ET VALE

INTERNATIONAL WOMEN ENGINEERING DAY

JOURNAL PUBLICATION: Structural rigidity theory applied to the scaffold-free (dis)assembly of space frames using cooperative robotics

This paper presents a fabrication-informed design method for triangulated space frame structures that remain stable during all phases of their robotic assembly and disassembly without requiring external scaffolding. A graph theoretic framework, based on rigidity theory, is developed to allow the structure, its support conditions, and the impact of robotic support constraints to be simultaneously represented in a single topological framework. The structural system is sequentially designed with an assembly logic based on Henneberg graph-construction steps, which are executed with two robots through a cooperative rigidity-preserving sequence. Ensuring planarity of the resulting graph during these construction steps is shown to lead to intrinsic disassembly potentials within the system. A graph-based algorithm is presented to locate, isolate and remove locally rigid tetrahedral cells formed in the structural system. This algorithm is then utilized to compute a rigidity-preserving robotic disassembly sequence. The design method is demonstrated in the case study design of a wooden space frame arch structure that is robotically (dis)assembled.

PUBLICATION: shells and gridshells for long-span roofs

Structural Principles-Suitable Spans-Inspiring Works: all those things in the newly published DETAIL Manual of Structural Design. It even includes a chapter on shells and gridshells written by me -)

FPO: Tianju succesfully defends his doctoral work!

Congrats to Tianju for successfully defending his PhD dissertation on “Computational Modeling and Design of Mechanical Metamaterials: A Machine Learning Approach” today 5th January 2022!

NEW 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 mechanics and design of elastic rod network. The research will be conducted under the direction of Professor Sigrid Adriaenssens. 

Responsibilities will include: 
- Developing a numerical framework that efficiently solves static equilibria and bifurcations in elastic rod networks, a stability test that determines the stability of the static equilibria, and an optimization framework that assembles fundamental network cells to elastic structures with tunable mechanical properties and geometries;
- Overseeing day-to-day graduate 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;
- A strong background in theoretical mechanics and applied mathematics, with an expertise in the mechanics of thin rods and strips, stability analysis, and optimal control theory. Experiences with analytical modeling, boundary value problems, numerical continuation, and table-top experimental mechanics will be a plus;
- Strong project management skills and a very good publication record.  

More details here

FUNDING: NSF HDR INSTITUTE FOR DATA-DRIVEN DYNAMICAL DESIGN

Harnessing data for materials discovery goal of new $15M NSF Institute for Data-Driven Dynamical Design

Scientists and engineers are constantly on the hunt for novel materials and structures that combine valuable properties in new ways.

But what if they could harness the power of data science to discover fundamentally novel materials – for everything from carbon dioxide separation to better fuel cells to earthquake-proof buildings – at a far more accelerated pace?

A new $15 million interdisciplinary research institute led by Colorado School of Mines aims to create new theoretically grounded and experimentally validated approaches and tools to design and discover dynamical materials and structures while solving long-standing scientific challenges in the dynamical response of materials.

The NSF’s Institute for Data Driven Dynamical Design (ID4) is one of five new Harnessing Data Revolution Institutes funded through a $75 million investment announced today by the National Science Foundation to enable new modes of data-driven discovery that allow fundamental questions to be asked and answered at the frontiers of science and engineering.

The Mines-led institute brings together data scientists, engineers, physicists, chemists and material scientists from 11 other institutions across the U.S.: Northeastern University; University of Illinois Urbana-Champaign; Drexel University; Northwestern University; University of California, Los Angeles; University of Central Florida; Harvard University; Princeton University; Washington University in St. Louis; Tufts University; and industry partner Kebotix, Inc.

“Over the last decade, we’ve seen major advancements in using big data to predict new materials. What makes this institute different is a focus on the discovery of new pathways and mechanisms rather than just targeting a final property. This is crucial if you want to move beyond incremental improvements and interpolation – by analogy, if you knew how to swim a doggie paddle and a backstroke, you’re not going to interpolate to the dolphin stroke,” said Eric Toberer, director of the Materials Science Program at Colorado School of Mines and lead investigator on the institute. “We’re excited to develop exploratory search methods for finding new dynamics. In the long term, such dynamics might ultimately involve materials, macroscopic structures, biology, geophysics or even finance.”

To do that, the institute will address three core data science needs: new representations and learning architectures that capture the time evolution of complex materials; efficient exploration of time-dependent design spaces; and new visual analytics tools to incorporate human feedback into the design process.

The initial focus for material discovery will be four spaces already at a “tipping point,” where large quantities of dynamical data can be readily created: crystalline solids with tailored ion transport for fuel cells and batteries; pressure-sensitive metamaterials for robotics; light driven catalytic reactions for chemical production; and synthesis and assembly of porous frameworks for chemical separations.

The ultimate goal, Toberer said, is to develop algorithms and mechanisms that are cross-cutting enough to be able to solve a wide variety of material challenges in complex time-evolving systems.

“We’re very agnostic to the application – in the near term we are interested in better materials and reactions, but long term, we’re also trying to create open-source software that will help people beyond this team,” Toberer said. “It would be a disaster if we wrote something that was so specialized it could only solve one problem.”

Among the members of the interdisciplinary research team are experts in machine learning, knowledge structures and visualization, as well as organic chemistry and catalysis, ion and gas transport, metamaterials and structural materials. Co-PIs are:

Ryan P. Adams, Professor of Computer Science at Princeton University
Sigrid Adriaenssens, Associate Professor of Civil and Environmental Engineering at Princeton University
Katia Bertoldi, William and Ami Kuan Danoff Professor of Applied Mechanics at Harvard University
Remco Chang, Associate Professor of Computer Science at Tufts University
Adji Bousso Dieng, Tenure-Track Assistant Professor of Computer Science at Princeton University
Abigail Doyle, Saul Winstein Chair of Organic Chemistry at University of California, Los Angeles
Elif Ertekin, Associate Professor of Mechanical Science and Engineering and Andersen Faculty Scholar at University of Illinois at Urbana-Champaign
Roman Garnett, Associate Professor in the Department of Computer Science & Engineering at Washington University in St. Louis
Diego Gomez-Gualdron, Assistant Professor of Chemical and Biological Engineering, Colorado School of Mines
Jane Greenberg, Alice B. Kroeger Professor and Director of the Metadata Research Center at Drexel University
Sossina M. Haile, Walter P. Murphy Professor of Materials Science and Engineering and of Applied Physics at Northwestern University
Boris Kozinsky, Associate Professor of Computational Materials Science at Harvard University
Steven Lopez, Assistant Professor in the Department of Chemistry & Chemical Biology at Northeastern University
Alvitta Ottley, Assistant Professor in the Department of Computer Science & Engineering at Washington University in St. Louis;
Semion K. Saikin, Chief Science Officer at Kebotix, Inc.
Fernando Uribe-Romo, Associate Professor of Chemistry at University of Central Florida

The institute’s work will also include a robust outreach program, including summer coding schools for high school students, undergraduate research opportunities, and one-year internships for recent college graduates who attended schools without undergraduate research programs. In the later years of the five-year program, the institute also plans to offer graduate student fellowships, where doctoral students from universities not affiliated with the institute could come and learn the tools, contribute to their development and then bring them back to their own labs.

UCL PRESENTATION: FINDING FORMS

On Monday November 15th, I am presenting our work on large-span structures to the students of the Engineering and Architectural Design Program at University College London. Looking forward to it!

BARKOW-LEIBINGER STUDIO: Let’s talk Form Finding

Fragility, proportion, asymmetry, the hand/mind connection, the unplanned, evolution and being informed are recurring themes in the artist Stephen Talasnik and the Form Finding Lab work and research. A panel presentation and discussion at the Barkow-Leibinger Studio, Cornell University, 10th November 2021.

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.”

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.

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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 16^th 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.

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 20^th 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.

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 20^th 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 30^th 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 7^th though 10^th 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.

Form Finding Lab – Princeton University