While We Wait: how stereotomy enables meditation

Elias and Yousef Anastas_008_Copyright Edmund Sumner
“While We Wait” at the Victoria & Albert Museum, London (Photo: Edmund Sumner)

While We Wait is a meditative installation by Bethlehem-based architects Elias & Yousef Anastas about the cultural claim over nature in Palestine. Yousef is a Form Finding Lab alumnus.

The towering structure consists of small elements of stone from different regions of Palestine, fading upwards from earthy red to pale limestone. The stone elements are shaped by both revolutionary and traditional techniques: they are designed on a computer, cut by robots, and hand-finished by local artisans.

The process of ‘stereotomy’, the art of cutting stones so they can be assembled into a larger configuration, enables the lace-like structure to support itself. Moreover, gaps between the stones allow the viewer to see out, while being encouraged to imagine the installation’s eventual surroundings in Palestine through evocative sound and video elements.

After being exhibited at the Victoria & Albert Museum (London, UK), While We Wait is destined to live permanently in the Cremisan Valley, where the controversial separation wall is currently being built, threatening to segregate the community, isolate land from its owners, and sever the historic link between the valley and its eponymous monastery.

In stark contrast to the rectangular concrete wall, which dominates and divides the Palestinian landscape, this installation will venerate its extreme natural beauty. Returning to the very earth from which it was made, it celebrates the visual, symbiotic relationship between nature and architecture. Moreover, the structure will unite the local community by becoming the focus of their non-denominational Friday gatherings in protest of the wall. While We Wait therefore suggests an alternative to the cultural claim over nature.

(Photo: Mikaela Burstow)

Project information:

While We Wait is an installation by Elias & Yousef Anastas commissioned by the Victoria & Albert Museum in London. It was exhibited September 16-24 at the Daylit gallery.
While We Wait will be on show at Alserkal Avenue in Dubai on November 6th.
Authors: Edmund Sumner, Mikaela Burstow, and the Form Finding Lab


What I am thinking: differential geometer and structural engineer Allan McRobie

On Wednesday, the academic bookshop Heffers at Cambridge (UK) was packed for the book launch of “The seduction of Curves: the lines of beauty that connect mathematics, art and the nude”. The author Allan McRobie is a Reader in the Engineering Department at the University of Cambridge, where he teaches stability theory and structural engineering. He previously worked as an engineer in Australia, designing bridges and towers. We are intrigued by the work and writing of Allan and asked him some questions.

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Sigrid Adriaenssens: Why did you, a structural engineer, write a book about the seduction of curves?

Allan McRobie: My structural engineering specialism is stability. Even if my buildings are boringly rectilinear, more like a standard office block than your lovely gridshells, their stability is governed by a smoothly curved energy surface.  My stability lectures are thus full of curves. A few years ago, I introduced life drawing classes to the Engineering Department here in Cambridge, and in one such class it occurred to me that the curves I was so contentedly drawing on my sketchpad were speaking the same language as the curves in my stability lectures – a beautiful language of folds and cusps and swallowtails. The worlds of careful engineering calculation and of freer graphical expression were thus suddenly and unexpectedly linked. And the more I thought about the link, the more it exploded into wider realms of optics, physics, architecture and art. My book even has a section on the history of landscape gardening, and another – related to the seduction part of the title – on evolutionary biology. To my mind at least, these areas are all connected by a rather beautiful thread of ideas, all related to curves.


What is the relationship between art, the nude, and engineering?

The curves are the link. In stability theory, there is a precise notion of how you look at a curved surface, and of how the act of perception creates outlines. In engineering these are the stability boundaries we must not cross. Exactly the same happens in art – how the act of perception of a painter or a photographer takes a smooth surface curving through 3D – the body of the model –  and “flattens” it down to 2D in the painting or the photograph. Or when you look at a sculpture, your eyes create a 2D image of the 3D object on your retinae. The language of folds and cusps is created by this “flattening”. The reason “the nude” enters is because the nude constitutes a large part of art history, and because a large part of our fascination for curves originates, I believe, from evolutionary biology. The bodies of our mates are curved and our genes predispose us to like the body shapes of our mates. I think a number of architects have drawn on this. Obviously there is Oscar Niemeyer, but also more recently, Future Systems have knowingly tapped into this with their Selfridges in Birmingham, UK.  I think a lot of beautiful modern buildings draw on this, but without saying so.


What is your favorite curve and why?

Like Salvador Dali, my favourite curve is the swallowtail. It has two back-to-back cusps connected by folds.  You can find swallowtails in many beautiful locations on the body.  I chose a lovely example for the cover of my book. For me, it is rather emblematic of how the mathematics of catastrophe theory has something to contribute, not just to the understanding of downfall and disaster, but to beauty. For me, the swallowtail is The Line of Beauty.

The swallowtail curve

Can you give an example of where this curve (or another curve) appears in engineering theory and can you explain the meaning of that engineering curve?

The easiest example is the cusp. In my book, I describe how a cusp can most readily be found on a sort of “ski slope” surface. On one side of the ski slope you can ski down smoothly, as per usual. On the other side, there is a smoothly overhanging precipice, and if you ski down that side, you have to jump from the overhanging lip to the slopes below.  There is a smooth transition between the two sides, so the whole ski-slope is smooth everywhere.  If you draw that ski-slope, you end up drawing a cusp.  Now, not only can you find this morphology at many beautiful places on the body, but that surface is exactly the object that underlies my first three lectures on stability theory. I can explain exactly how a column does or does not collapse by looking at that surface from different directions.


What is your greatest achievement and why?

Well, after my children and any positive contribution I may have made to my students, it is probably one of my recent papers on graphic statics. It is entitled, rather pompously, The Geometry of Structural Equilibrium, and it extends the field of graphic statics into whole new realms of possibility. It only appeared this year, in the Royal Society Open Science journal. One thing I really like is that the description of structural equilibrium that emerges looks remarkably like Maxwell’s description of electromagnetism.  The geometry that Maxwell used to fuse electricity and magnetism into a coherent whole – electromagnetism – was so radical that it did not even fit into the Universe. It took another forty years before Einstein came along and said “Well, we’d better change the Universe then”. Maxwell was also one of the founding fathers of graphic statics, and whilst my contribution is utterly minor in comparison, I like to flatter myself that if anyone would like my new description, it would be Maxwell.

Oh, and I think the ending of my book is pretty good, too. I am secretly quite pleased with that.

What question are you never asked and would like to be asked? What would be the answer?

That’s a good question but a tough one. I guess it is all those questions whose answers are important, but where no-one ever asks my opinion, let alone follows it. One example would be my views on student fees in the UK. I think they are a disgraceful injustice, a tax by which my generation trick young people into paying off our debts. This deeply affects me as a University lecturer. Previously I taught because I enjoyed it, and students listened because they wanted to.

Now, I am told that I am just paid to deliver a service that will allow those who pay me to go out and earn a higher salary. That is not why I get out of bed every day. Fortunately, my students remain as wonderful as ever, but I am deeply embarrassed by the knowledge that each of them will be repaying my wages for decades to come. It is such an injustice, and no-one ever asked me – they simply made me complicit in it all.

All images courtesy of Allan McRobie and Helena Weightman, unless otherwise specified.

Check out the book, The Seduction of Curves, here.






IASS 2017: Highlights from Hamburg

At the end of September, hundreds of students, university faculty, industry experts, and innovators convened in Hamburg, Germany for the annual International Association of Shell and Spatial Structures (IASS) symposium. Apart from the numerous technical presentations, those in attendance were also treated to a series of excellent and inspiring keynote presentations. Check out some of the big picture ideas from the plenary sessions below.

Participants gather at Hafen City University for the IASS 2017 Symposium

Biological Design and Integrative Structure
Prof. Dr.-Ing Jan Knippers
Head of the Institute for Building Structures and Structural Design (ITKE), University of Stuttgart
Knippers Helbig Advanced Engineering, Germany

After a series of opening exercises, conferral of awards, and recognition of the late Wilfried Krätzig and Klaus Linkwitz, Jan Knippers of Thorsten Helbig Advanced Engineering took the stage to deliver the first keynote address of IASS 2017.

Nature has many lessons for designers. From naturally varying densities in sea urchins to clever arrangements of non-isotropic fibers in lobsters, Dr. Knippers shared some fascinating examples of how nature uses materials in smart ways and how these observations can be applied in practice.

For example, at the Institute of Building Structures and Structural Design (ITKE) at the University of Stuttgart, Dr. Knipper’s group has been quantitatively studying the Schefflera aboricola (aka the sand dollar), which gave rise to their 2016 Research Pavilion. Other work has focused on understanding how nature arranges fibrous material and how to recreate such patterns using advanced robotic weaving technology.  Check out the video from ITKE about their latest pavilion inspired by silk-producing moths.

Why buildings should start to float, or towards the flying architecture 
Tomás Saraceno
Studio Tomás Saraceno, Berlin, Germany / Argentina 

Architect, artist and scientist Tomás Saraceno came to the symposium to share his curiosity of spiders, giving the audience fascinating insights into their silky constructions and accompanying imagery that could put even the most extreme arachnophobe at ease. After realizing that science has paid too much attention to spiders and not enough to spiderwebs, Tomás began to study webs in detail, developing proprietary techniques to digitally scan their intricate structures in detail and even amassing a museum-quality collection of 500 different types of webs. These pursuits led to a poetic realization that our world is filled with webs: spider webs, cosmic webs, and social webs.

By releasing enough fine silk to sustain lift in air currents (aka “ballooning”), spiders can travel long distances, with some even making it into the jet stream. Inspired by such feats, Tomás started the Aerocene concept, envisioning a future where people can inhabit the skies in lighter-than-air structures supported by solar updrafts. Check out his other projects at his website  tomassaraceno.com.

Building Art Invention
Research and Development of Innovative Materials at the Convergence of Art, Architecture and New Technologies
Prof. Heike Klussmann
School of Architecture, Urban Planning and Landscape Architecture, University of Kassel
Heike Klussmann Studio Berlin, Germany

Architect and artist Heike Klussmann’s works spans various scales, from macro to micro. Together with netzwerkarchitekten, she helped develop the concept behind the Wehrhahn metro line in Dusseldorf, where architecture and art blend seamlessly: a city-scale underground “continuum” punctuated by six unique “cuts” (the stations). At the smaller scales, she develops building materials and technologies that blur the definition of art. For example, Touchcrete  is an electrically conductive concrete that could find applications in lighting control, parking spot management and traffic monitoring. 

Check out her work here: Baukunsterfinden.org Kennwert.com Klussman.org

Engineering the Museum: Structure and Exhibition
Prof. Guy Nordenson
Princeton University, School of Architecture, Princeton, USA
Guy Nordenson and Associates (GNA), New York, USA

Guy Nordenson is a structural engineer and professor at Princeton University. His practice is especially known for its experience in the museum sector. In his IASS keynote, “Structure and Exhibition,” he reflected on past projects and on how engineering and architecture come together to create world-class exhibition spaces. For example, in the Corning Museum of Glass in New York, Guy Nordenson worked with architects at Thomas Phifer and Partners to create a new freestanding addition, the Contemporary Art & Design Wing. GNA’s slender and closely space precast concrete rafters help modulate the direct light from the skylights above, bathing the all-white interior in a gentle glow.

Other museums and exhibitions spaces by GNA include the National Museum of African American History and Culture in DC and the New Museum in New York City. See the rest here.


Beyond Lightweight – Building the World of Tomorrow
Prof. Dr.-Ing. Dr.-Ing. E.h. Dr.-Ing. h.c. Werner Sobek
Head of the Institute for Lightweight Structures and Conceptual Design (ILEK), University of Stuttgart
Werner Sobek Group, Germany

Dr. Sobek’s public lecture centered around a back of the envelope calculation he did one morning: how much building material would we need per second to provide the growing population with a German living standard? Currently, the average German owns around 490 tons of building material – about half of which is infrastructure – while the world average is only 110 tons. According to his math, we would need 1274 tons per second to provide these people with the German standard.

In light of this calculation, Dr. Sobek, proposes two necessary rules: 1) build for more people, but with less material, and 2), do not use any more fossil fuels. To follow these rules, he predicts we will gravitate towards an all-electric society heavily reliant on prefabrication, recycling, and adaptive structures. He encapsulated these concepts recently in a prefab home currently for sale (the Aktivhaus), and his ultra-thin “smart shell” in Stuttgart that dynamically adjusts its supports to support loads with less material (check out the video below). Finally, just like Jan Knippers before him, he also stressed the importance of learning from nature.


“People Who Need People”
Neil Thomas
Atelier One, UK

Engineer Neil Thomas of Atelier One delivered the final keynote, entitled “People Who Need People.” Presenting his work, he reflected on all his collaborations and the way that people of various backgrounds — architects, artists, musicians, mechanical and environmental engineers — came together to realize some remarkable and inspiring projects.

Thomas opened with some of his work with Mark Fisher, the architect responsible for the dazzling stage designs seen at Pink Floyd, The Rolling Stones, and U2 concerts. Fisher also introduced Thomas to Frederic Opsomer (PRG Projects), a pioneer of lightweight modular LED screen technology. Together, the trio achieved feats of engineering that made giant video screens ubiquitous at concerts worldwide. Thomas also stressed the contributions of artist Dicky Bentley (“what he can’t draw, can’t be drawn), and Andy Edwards (Brilliant Stages), a mechanical engineering genius behind the Rolling Stone’s Bridges to Babylon and Take That’s giant “Om Man.”

Thomas then shared his many artistic collaborations, implying that the art’s success hinged on making the engineering aspects seem effortless. For example, working with artist Adam Scott and wind expert Doug Greenwell, they created a kinetic sculpture inspired by dune grass. Amazingly, these giant grasses freely oscillate at low wind speeds, but come to a rest when the wind start to pose a structural threat. Thomas’s other collaborators include artists such as Anish Kapoor, Marc Quinn, and Rachel Whiteread:

Thomas ended his talk with a focus on sustainability and the environment, showing work done in Bali with bamboo-genius John Hardy (such as Sharma Springs, Three Mountains, and the Green School), as well as projects with Patrick Bellew (Atelier Ten). Bellew was instrumental in the award-winning “Gardens by the Bay” in Singapore (Grant Associates & Wilkinson Eyre Architects) as as well as the net-zero carbon Kroon Hall at Yale University (Hopkins Architects).





Structures in the Low Countries: the footbridge Lichtenlijn in Knokke

This is the first post in a series on Structures in the Low Countries where I am spending time this Fall doing research and meeting interesting people.

On a beautiful Fall afternoon, I stumbled across the Lichtenlijn footbridge in Knokke Heist, a resort town at the Belgian coast.

With its undulating shape, the bridge evokes the image of waves and sails. (credit Sigrid Adriaenssens)

The bridge reminds us of sails, the wind and waves.  It connects the dike and a nature reserve and enhances the location of two historic lighthouses that guide ships to safe shores (hence the bridge’s name Lichtenlijn which means Line of Light in Dutch).

The slenderness and the expressive overall geometry evokes the image of a hammock tensioned above the local flora. (credit Sigrid Adriaenssens)

The bridge reminded me of what the French philosopher Saint Exupery  wrote in Terre des Hommes (1939):

“It seems that perfection is attained not when there is nothing more to add, but when there is nothing more to remove.”

The Knokke-Heist footbridge ( 2008), was designed by Ney and Partners unlike traditional structures. The overall geometry is based on hanging cloth model principles (like the shape of a hammock). The bridge has a curved plan and is supported at two intermediate mast supports and at the abutments.  The plan curvature responds to the site conditions and the suspension at the masts provides interesting viewpoints for the pedestrians and cyclists on the bridge.

The bridge is suspended at 2 intermediate mast supports and supported at 2 abutments. (credit Sigrid Adriaenssens)

The overall geometry was further refined to comply with the CNC manufacturing constraint of single-curvature steel sheet bending, and was then numerically optimized to maximize the overall stiffness of the bridge.

Viewpoints on the bridge

The latter task presents a typical topology optimization problem that consists of distributing a given amount of material in a design domain subject to load and support conditions, such that the bridge stiffness is maximized.

Topology optimisation result in openings in the bridge which act as view concentrators.

The figure below shows the optimal thickness distribution in the bridge surface for different values of the thickness ρmean, which is a measure of the total material volume constraint.  By combining topology optimization with form finding and CNC manufacturing constraints, a 3D typology was found that might not have been conceivable in a purely analytical or intuitive fashion.  At the Form Finding Lab, we investigated this bridge and its topology optimization, you can find out more about it  here.  Soon we will visit the form found cupola over the Dutch Maritime Museum in Amsterdam. Stay tuned for more interesting structures in the Low Countries!

Optimal material distribution in the thickness of the shell

Location: Elisabethlaan, Knokke Heist, Belgium

Author:  Sigrid Adriaenssens

Reporting from IASS 2017 – Severe Conditions & Disasters

Last week at the IASS the Form Finding Lab was very involved in the session on severe conditions & disasters. The session was chaired by our own Sigrid Adriaenssens and close collaborator Prof. Ruy Marcelo Pauletti from the University of Sao Paulo, and many more collaborators presented their research.

The revue of familiar faces started with Eftychia Dichorou from the University of Cambridge. Dichorou presented her work co-authored by Matthew DeJong (Cambridge University) and Giorgia Giardina (University of Bath) on the finite element modelling to predict cracking and seismic collapse of a thin masonry shell structure. Dichorou presented a quick historical overview of tile vaulting after which she focused on the impact of earthquakes on these structures. To model the effect of earthquakes, she presented a parametric study of the Droneport Project which was built last year at the Venice Biennale. She demonstrated the importance of accurately quantifying material properties of the masonry, particularly to capture its post-peak behavior, and also pointed out the need to understand the impact of geometric imperfections.

Dichorou’s presentation was aptly followed by an application of tile vaulting in Istanbul. Indeed, Ahmet Topbas from the structural design firm Ateknik, together with Dogan Arslan presented their recent construction project on the Seismic design, detailing and construction of the first Catalan Vault and Domes of Istanbul. They showed how the Guastavino vaults of New York inspired them to build new brick masonry vaults during the restoration of the Hatice and Fehime Sultan Palace near the crossing of the Bosporus. They strengthened the vaults to account for earthquake loading by adding steel rebar as well as a coil steel-mesh.

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Ahmet Topbas from the structural design firm Ateknik, together with Dogan Arslan showing the plans of the vaults .

Then the session shifted from masonry shells and earthquakes, to the modeling of cable net under other impact loads. Romain Boulaud from the Ecole Des Ponts ParisTech presented a sliding cable model for rockfall barrier simulations. He detailed the behavior of these flexible barriers, showing their strong nonlinear behavior (both geometric as material). These strong nonlinearities were accounted for in simulations relying on dynamic relaxation, which showed a robust, yet time-consuming solution.

Form Finding Lab PhD candidate Olek Niewiarowski then presented his Master’s thesis work on cable nets subjected to underwater loads, reminiscing about his brief tenure at Reunion Island to investigate nets used as barriers against shark attacks. Niewiarowski detailed his numerical model, and showed how the topology of nets can be impacted to better distribute the forces arising from the breaking waves.

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Olek Niewiarowski showing how to integrate breaking wave simulations.

Stefano Gabriele from the university of RomaTre got the final word and presented the work on the funicularity of shell structures he had elaborated with Giulia Tomasello (among others). Gabriele explained a new easy-to-read method to quantify whether a form-found shell structure works predominantly through membrane action, rather than through bending. The method hinges on the computation of the eccentricity (relating bending moment and normal force) in every point of the shell. The method was applied to modal stress distributions under different loading conditions, including earthquake loading.

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Prof. Gabriele explaining his new approach on how to evaluate how funicular shells are under applied loading.

The session was concluded by noting how surface structures such as shells, membranes and nets are particularly well suited to resist extreme loading.

Author: Tim Michiels

How to form find shells that withstand earthquakes? We asked Tim Michiels who was just awarded the prestigious Hangai Prize.

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.


Tim’s research was co-authored by Prof. Adriaenssens and Prof. Jorquera-Lucerga of the Universidad Politécnica de Cartagena. It presents a form finding approach that allows for the shape generation of masonry shells in seismic areas. There is a renewed interest in constructing these masonry shells because of their low carbon impact, spurring the need to understand how such shells should be designed in seismic areas. Earthquakes are expected to have an important impact on the behavior and thus the shape of these medium-sized shell structures, as their large horizontal forces induce large bending moments that cannot be accommodated in thin, zero-tensile strength shells. Nevertheless, currently available form finding techniques for shells, rely solely on gravity loads for the generation of their shape and do not account for seismic loading.

Examples of two recently constructed masonry vaults. Left: residential house in Oaxaca by Ramon Aguirre Morales (Image credit: Ramon Aguirre Morales). Right: Venice biennale droneport project by Odb, Block Research Group, Norman Foster Foundation and Redline (Image credit: Michiels)

Therefore, the masonry shells are form-found for both vertical gravity and horizontal seismic loading so that a compression-only load path exists within the thickness of the shell. Through the application of an inverted hanging net 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. It is suggested to implement the obtained forms as interconnected double-layer thin shells, so that an equilibrium thrust surface can form over a wide depth of the structure, while maintaining the construction advantages of thin-tile vaults.

World map overlaying seismic risk and locations with tradition of earthen construction (Image: Michiels et al., 2017).

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.  The research demonstrates how to tailor masonry shells for a resilient built environment and can be extended to the shape generation of shells constructed out of other compression-only materials such as unreinforced concrete, stone and earth. The full paper will be published in the upcoming issue of the Journal of the IASS.

Initial shapes for double layer shells based on a rectangular grid (Image: Michiels et al. , 2017)

What I am thinking: fiber sculptor and urban artist Janet Echelman

Janet Echelman smiles in front her Tsunami Series (image credit Janet Echelman)

Janet Echelman is an American artist whose urban installations playfully respond to wind and light. In her work Echelman exploits the inherent beauty of common materials such as fishnets and atomized water particles in a design approach that elegantly combines ancient arts and craft with 21st century digital and numerical techniques.  To speak to her genius, she has received the Guggenheim Fellowship, the Harvard University Loeb Fellowship, a Fulbright Lectureship, and the Aspen Institute Crown Fellowship.  She was ranked number one on Oprah Magazine’s List of 50 Things that Make You Say Wow!  We are so honored that Janet was so generous with her time and gave us this inspiring interview.

Sigrid Adriaenssens: How do you describe the aesthetics of the soft surfaces you design and build, and why do they have such an impact on the public?

Janet Echelman: My work exists at the intersection of art, architecture, computer and material science, and public space. I often experience cities as hard-edged and rigid – mostly concrete, steel and glass laid out in straight lines. I’m drawn to humanize the city to the curves and softness of the human body, bringing the scale of skyscrapers down to the size of hand-knotted mesh, because those spaces make me feel at ease. The softness of my art becomes a counterpoint to the city, as I install billowing, hand-knotted net sculptures to bridge the gap between an industrial skyscraper and my body. I observe that these crafted, textural connections often engender a sense of social interconnectedness as well.

She Changes, Porto (image credit Janet Echelman, Enrique Diaz)

I think art in the public sphere is vitally important. I want my work to be as accessible and free as breathing air. I see art, architecture and landscape as interwoven elements that we can design in a way that improves our cities. They can be fused together to create a unified experience much greater than each entity can do alone.

I leave my work open to interpretation, for each person to complete. My hope is that each person becomes aware of their own sensory experience in that moment of discovery, and that may lead to the creation of your own meaning or narrative

How do you generate form?

My forms come from my search for inspiration from life. I guess this is my way of making sense of the world, and finding my tiny little moment within the larger unfolding story of humanity on our planet. For my traveling Tsunami Series artworks (1.26 and 1.8), the concept stems from scientific data sets of the earthquakes and tsunamis in Chile (2010) and Japan (2011) respectively, and the observation that our actions are interwoven into the complex network of the earth’s natural systems.

1.26 Sculpture Project at the Biennial of the Americas (image credit Janet Echelman)

My studio generated the 3D form for the sculptures using NASA and NOAA data that measured the effects of the earthquake including tsunami wave heights across the oceanic expanse. The resulting vibrations momentarily sped up the earth’s rotation, shortening the length of the day by micro-seconds, which became the catalyst for the sculpture series.

I also turn to the unique site as a guiding force for each artwork. When I make the first site visit, I get feel for its space, talk to the people who use it, and spend time uncovering its history and texture to understand what it means to its people. I work with my colleagues to brainstorm, sketch, and explore all ideas, without censoring our ideas in the early stages. As the sculpture designs begin to unfold, our studio architects, designers and model-makers collaborate with an external team of aeronautical and structural engineers, computer scientists, lighting designers, landscape architects, and city planners to bring my initial sketches into reality. We fabricate our artworks through a combination of hand splicing and knotting together with industrial looms, and then install on location. It is a collaborative and iterative process that can take more than a year.

What is the relevance of traditional crafts in your work? and What is the relevance of digital techniques?

I think it’s interesting how we’re making monumental sculpture with pre-industrial and industrial methods, but we require post-industrial computer tools in order to build at the scale of the city. I see it as connecting our past, present and future.

When I began making my netted sculptures, they were fabricated completely by hand. All of my recent works are a combination of machine and hand-work. My studio uses hand-work to create unusual, irregular shapes and joints, and to make lace patterns within the sculpture. We utilize machines for making rectangular and trapezoidal panels with stronger, machine-tightened knots that can withstand intense hurricane-force winds, and the heavy weight of snow and ice storms. Industrial equipment and materials have helped me bring my work to a new scale and permanency.

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Detail Net (image credit Janet Echelman)

My studio has been collaborating the past 6 years with the world’s leading design software company (Autodesk) to build a custom software tool that allows us to soft-body 3D modeling of our monumental designs while understanding the constraints of our craft, and showing response to the forces of gravity and wind. We couldn’t have built our monumental city-scaled sculptures without it.

How do you match the ephemeral floating nature of your nets with the permanence needed for urban interventions? What makes your collaboration with engineers successful?

I work closely with aeronautical and structural engineers and material scientists throughout the design process, and regular communication and problem-solving together makes it successful. It is a gradual, collaborative, and iterative process from every angle, and often takes more than a year to get from my initial sketch to the final artwork.

Some parts of the form are structural and carry significant wind loads, so are made of a fiber more than 15 times stronger than steel (Ultra-high-molecular-weight polyethylene). The colored portions of the sculpture are designed to withstand UV while remaining soft and able to gently billow in the wind (Poly-tetra-fluoro-ethylene).  The final materials in my sculpture are the projected colored light, which mixes with the physical color, and the context of buildings, ground, and people, who together complete the artwork in my mind.

Skies painted with unnumbered Sparks, Vancouver (image credit Janet Echelman, Ema Peter)

What is your greatest achievement and why?

Shaping a life.

What question are you never asked and would like to be asked? What would be the answer?

What inspires you?

The ancient carved stone caves of Ellora in India, the immense stones of the Coliseum and imagining the gargantuan textile Velarium that used to float above it, the Ikat weavers in Indonesia, the gesture of a master calligrapher brushing ink on rice paper, watching a skyscraper’s bamboo scaffolding survive a typhoon while its concrete foundation cracks, watching the mapping of fluid dynamics from a bat’s wing in flight.

I look all around me for inspiration – at the forms of our planet in macro and micro scale, to the patterns of life within it, to the measurement of time, weather patterns, or the paths created by fluid dynamics.

Bell Bottoms – More than U Can Chew (Image Credit Janet Echelman)

You will see Janet’s nets floating in the air here and here and her inspiring Ted Talk here.

So long sweet summer

Lichtenlijn Footbridge Knokke-Heist (left)

After a long sweet summer, we head back to school full of fresh ideas, energy and enthusiasm. We have a great semester ahead full of exciting events, awards, interviews, research reports and structural reviews.

Singapore Janet Echelman (left credit Janet Echelman), Parkbrug (right credit Jonathan Ramael)

To lift the tip of the veil, we will bring you an inspiring interview with the internationally renowned sculptor and fiber artist Janet Echelman, life reporting of the main discussions at the 2017 Hamburg IASS Conference (International Association of Shell and Spatial Structures), reviews of the newest and most exciting structures in the low countries (including 2017 Footbridge Award Winner Parkburg), up-dates on  the research at the Form Finding Lab and we will find out what alumn Yousef Anastas is upto at the London Design Festival .  Stay tuned.  Fall here we come!

“While we wait”, Yousef Anastas at the Victoria and Albert Museum during the London Design Festival (image credit Yousef Anastas)

Form and Force in Cairo’s Convertible Umbrellas

We are visiting the American University of Cairo for an educational and research collaboration on hygroscopic surfaces.  In Old Cairo, we had the surprise of running into convertible textile umbrellas in front of the Al Hussein Mosque, Cairo, Egypt designed and built by SL Rasch GmbH Special and Lightweight Structures in 2000.  These umbrellas are similar to the large retractable umbrellas in front of the Prophet´s Holy Mosque in Medina, Saudi-Arabia.  I have always been a fan of the way the seam patterns in this doubly curved prestressed membrane are key to the design of the canopy and how the patterns fit into the local context.

These adaptive umbrellas shade the floors in front of the mosque when needed and create a comfortable microclimate throughout the year. Conceptually, the conic membrane form carries tensile forces through a series of horizontal rings and radial lines.  For me, these umbrellas are one of the archetypal prestressed membrane forms. Therefore I would like to use them as an example to better understand the relationship between form and force in pre-stressed membranes.

The umbrellas do not have a simple cone shape. Since they have anticlastic curvature, finding the optimal form of these umbrellas is more complex. The surface shape of these conic membranes is determined by the ratio of stresses in the textile’s two perpendicular directions. When the textile is woven, the weft is the term for the thread or yarn which is drawn through the warp yarns to create the textile. Warp is the lengthwise or longitudinal thread in a roll, while weft is the transverse thread.

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Diagram illustrating the warp and weft in a woven cloth

In the conic membrane, the warp direction is represented by radial lines while the weft direction can be represented conceptually by the horizontal rings.

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Comparison between the real (top) and conceptual umbrella (bottom) showing radial (warp) and circumferential (weft) lines

In the following parametric study, the effect of changing the geometry of the umbrella is studied on the stresses in the warp and weft directions. We approximate the base as a circular base of 8.75m radius for simplification. Additionally, the opening where the mast of the umbrella is ignored.

Using the equations of equilibrium for general surfaces of revolution, the tensile forces and radii of curvature in each direction depend upon the normal pressure, p:

p= T1 / R1 + T2 / R2

Where T1 and T2 are tensile forces and R1 and R2 are radii of curvature in the warp and weft directions, respectively.

For this example we will call the warp direction D1 and the weft direction D2. In the form finding process we assume that no permanent external pressure acts upon the membrane (thus p=0). We are interested in finding the shape under a set of pre-stress forces in the warp and weft directions. Thus when the normal pressure for these umbrellas is equated to zero, the relationship between stresses in opposing directions is easy to find.

In this analysis, the ratio of these stresses will be examined. The mosque umbrellas have a height of 5.2m and an approximated radius of 8.75m at their widest horizontal ring.


T1 / R1 + T2 / R2 = 0 , where T1 = T2

T / R1 + T / 8.75 = 0 , so R1 = -8.75 m

This case uses the minimum surface area of fabric. In Case 2, the stresses in the weft direction is reduced to half of those in the warp direction.


T1 / R1 + T2 / R2 = 0 , where T1 = 2T2

T / R1 + 2T / 8.75 = 0 , so R1 = -17.5 m

This case creates a ‘flatter’ curve for the membrane which requires higher stresses in the warp direction to maintain its form. Comparing Cases 1 and 2, it can be observed that the stress and radius ratios are directly related.

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Illustration showing relationship between form and force in the umbrella in front of Al Hussein Mosque, Cairo, Egypt (R=8.75m for T1=T2 and R=17.5, for T1=2T2)

When the warp stress is k times as large as the weft, the warp radius is k times larger than the weft radius (see table below). Therefore, as k increases, the material stress increases, the warp radius increases, and the curvature of the cone decreases.

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Table showing the relationship between warp stress and warp radius

Cairo is without a doubt full of architectural gems. I am very grateful that my host, Prof. Sherif Abdelmohsen (American University of Cairo), and the excellent local guide Tarek showed me some of them.

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Me, posing in front of the Umbrellas.


Author: Sigrid Adriaenssens
Contributions: Hiba Abdel-Jaber
Editor: Emre Robbe


“A bridge is something in between”: the works of Siah Armajani, artist and poetic bridge builder

In November 2016 we traveled with our CEE418/VIS418 class, co-taught by visual artist Joe Scanlan, to Kansas City and discovered the fascinating bridge models and drawings of Siah Armajani, brought together for the first time by the curator of Kemper Museum of Contemporary Art, Erin Dziedic. A superb opportunity to delve into the philosophy and work of Armajani.

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Photo credit: https://i.ytimg.com/vi/OaIDsR8_9kQ/hqdefault.jpg

Siah Armajani was born in Tehran, Iran, in 1939. He was raised in a family of highly educated individuals and himself attended a Presbyterian missionary for Iranian students. After having joined the National Front (which drove out the monarchy in place at the time) for several years, Armajani finally moved to St. Paul, Minnesota to attend Macalester College, a private liberal arts college. He continued to study philosophy as he searched for a framework for his social and political ideas.  Since then, Armajani has continued to produce art which reflects these ideas, with a few designs of his becoming realities in the form of public bridges.

One of the primary ideologies behind Armajani’s bridge designs comes from German philosopher Martin Heidegger (1889-1976). As he expresses it, a bridge is a phenomenological gathering of “the fourfold”, a sustaining connection with object and idea, a gathering or “simple oneness” of “earth and sky, divinities and mortals”. Heidegger applied this to a table:

A table is a thing.

A table is a public structure.

A table is something in between.

A table unites the people and brings people together.

Armajani’s designs were founded on the principle that these four concepts could be applied to bridge in the same way they can be applied to a table:

A bridge is a thing.

A bridge is something in-between.

A bridge which is something in-between has a shadowy side until it becomes public.

What us before the bridge, after the bridge, above the bridge, and below the bridge

brings them together and makes them one neighborhood.

A bridge is part of the public landscape.

Many of his small-scale sculptures demonstrate these concepts. For example, his House / Bridge series achieves these four criteria, with a particular emphasis on the importance of what is before, after, above or below the bridge.

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From left to right: House Above the Bridge, House Before the Bridge, House Below the Bridge, House After the Bridge (1974-1975)

However, Armajani also created designs which explored defying these concepts. His Limit Bridge series included sculptures that were similar to his earlier bridge designs, with the glaring difference that they are not passable. 

Limit Bridge III (1972-1978)

Limit Bridge III, shown above, demonstrates this inconsistency. While similar in construction and style to his earlier Bridge with Base series, a grade separation and a wall between two sections prevent passage across. This strips the bridge of its practicality; as a result, according to Heidegger’s principles, the bridge no longer unites the people or links what is before and after the bridge, disqualifying it as a true bridge.

In addition to Heidegger’s fourfold principle, Persian poetry culture has had a major influence on Armajani’s work.

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The Khaju Bridge (Esfahān, Iran)

A source of inspiration was the Khaju Bridge in Esfahān, Iran. Its design is laced with elements of Persian architecture, such as its arches, but it is also decorated in Persian art and text in an effort to integrate it into its environment. Armajani borrowed from this method; in a less conventional approach to American architecture, his public bridge designs had physical text from certain poems inlaid into the structure. The ultimate goal of this was to allow the bridge to be “site-specific”; that is, using excerpts that allow it to integrate into the landscape.

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A line of Ashbery’s poem

The ideal result is a public work that harmonizing, useful, and aesthetically balanced. An example of this is one of Armajani’s most well-known bridge, the Irene Hixon Whitney Bridge. While the design is more in line with modern American bridge styles, a poem is also inlaid directly into the structure, visible to all who use it. The poem was written by American poet John Ashbery specifically for the bridge; as a result the text allows the bridge to integrate more fully into its environment, achieving Armajani’s goal. The text of the poem can be viewed hereOverall, these influences helped form Armajani’s unique architectural approach, which have created a number of bridges which integrate with their environments.

stuttgart bridge
Stuttgart Bridge (1994)
Bridge Over a Tree (1970)
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Irene Hixon Whitney Bridge, St. Paul, Minnesota (1988)

You can view the full exhibit here and watch an interview with him here.

author: Emre Robbe

editor: Sigrid Adriaenssens