What I am thinking: the engineer and architect Marc Mimram

Marc Mimram is a celebrated French engineer and architect with projects in France and around the globe. He generously shares with us his ideas on bridge design in conversation with PhD candidate Victor Charpentier.

Victor Charpentier (VC): Marc Mimram, you are both an architect and engineer. Yet you have said that when you are given a project, the greater part of the inspiration for the initial spark comes from a third field, which is study of the landscape and geography. Can you explain why this is so important to you and how this affects your designs?

Marc Mimram (MM): Each project should be specific. It has to be depending of the situation where it take place.

To become a coherent project, it has to be related to the geography, the horizon. It should express the relation to the ground, to the sky, to the landscape considered as a geography informed by history.

In that case the structural project can take roots in the reality and forget the abstract equation of strength of materials to express gravity, the movement of forces, the movement of light; being part of the situation, part of the world, belonging to the site.

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Whong Sheng Da Dao Bridge in Sino Singapour, Tainjin Eco-City (China). (Image provided by Marc Mimram)

Advanced technologies have allowed structural form finding to become an integral part of many recent design projects. How do you add your personal, creative touch to a process that can become largely computational? What are your thoughts on the role of this method for the future of engineering design?

MM: The process of computational form finding is a method of optimization and as such, it follows the development of the project. It is obviously important to develop the project with frugality but the rational process of development can be plural and the choice has to be related to the specific situation, taking into account the landscape, the topography but also the economical situation, the knowledge, the development of local craftsmanship, the local materials.

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Liu Shu footbrigde in the City of Yangzhou with a variable width of 3 to 5.7 m (Image provided by  Marc Mimram)

In the past decade, many of your larger bridge projects have been built in Asia or in North Africa in part because of more local design freedom. In your opinion, are there too many inhibitions in the field of construction in western countries? What could be improved to bring creativity and exploration back to construction while at the same time maintaining the high standards of safety?

MM: High standard of safety are compatible with creativity. What gives more freedom in developing countries is the capacity you have there to invent projects which are out of the classical and already well-known solutions. Too many references, too many regulations and codes embed innovation into a passive attitude.

Codes are understood as being safe manner to reproduce already known solution, instead of that, it should open the process of innovation considering the fantastic development of knowledge and new materials, the present situation of computational fabrication related to calculation, the necessity of considering the limitation of natural resources.

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Hassan II bridge in Salé Rabat (Image provided by Marc Mimram)

You are an engineer that understands efficient structural design. What is your thought process when you encounter a situation that demands the sacrifice part of the structural efficiency to benefit the overall architectural concept? Do you have a systematic method or would you rather work with your instinct? Can you describe an instance where you had to make this choice?

MM: I cannot make a real distinction between statics and architecture. They are completely linked. Efficiency is not only a matter of ratio, neither weight per surface, nor critical isolated members dimensions.

A coherent process depends of the situation, the local economy, the relation between the costs of materials and the costs of workers, between the capacity of using industrial products and the local knowledges and the capacity of craftsmanship, between the local resources and the importation of materials, between the capacity of prefabrication and the methodologies of lifting and construction.……

The efficiency has not an autonomous meaning related to structural design but has to be understood as a whole especially in developing countries.

The development of computational capacities, not only in the area of calculation but also of production gives a larger scope to rational process of conception, which have to be still rational but including a multiple criteria approach.

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Feng Hua bridge in Tianjin (China) with a length of 240 m and a span of 120 m  (Image provided by Marc Mimram)

Is it important for you to create a “style”?

MM: Architecture has not any relation with style or so call personal writing. This style effect would transform rational and sensitive process of conception into a consumerist process of production, transforming architecture into a generic product instead of  being related to the place, to the situation , to the world and the men that are transforming the project into a memory of the shared work.

The project is not a logo, it has always to be specific, generous, open to the world and related to its time.

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Jin Liu Liu in Bridge in Tianjin Eco-City in Sino Singapour (China) (Image provided by Marc Mimram)

Infrastructure often has the effect of isolating and dividing communities whereas buildings can be designed to have the opposite effect (i.e. to be open and connecting) for the public space. Do you have any ideas for how to design infrastructure to complement and become a positive, integral part of the public space rather than a deterrent?

MM: Infrastructure has often been considered as a necessary evil. It should be considered as a shared good. Power had been related to building, castle then public buildings. Now the shared place in the city is the public space. The space of everybody, the place of democracy. As such it should be shared with generosity. Bridges are always crossing borders, either historical, geographical or social borders. Sharing a unique geography, infrastructure considered as a public space become a link and a place articulating the local and the distant.

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Solferino footbridge in Paris (Image provided by Marc Mimram, photography by C. Richters)

Finally, do you see the advance of self-driving cars as an opportunity to redesign our infrastructure and the public space?

MM: The advance of self-driving cars will be a great opportunity to reconsider infrastructure as public space. I hope it will not consider roads as a project of pipes isolated from the geography, of the topography and solved as a problem of fluid mechanics instead of being part of the landscape.

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Beng Bu Bridge in Tianjin (China) spanning 102 m (Image provided by Marc Mimram)

 

 The Form Finding Lab would like to thank Marc Mimram and his team for this interview and providing the stunning photographs.

 Questions by Victor Charpentier. Edits by Tim Michiels.

 

Keeping Sharks and Rocks Away: A few of the countless applications of nets

 

 

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Some of Frei Otto’s sketches from the Institute for Lightweight Structure’s “Netze in Natur und Technik” (1975)

 

Nets have been a perennial source of fascination in fields as diverse as engineering, architecture, art, and mathematics. As such, thinkers in these fields have come up with a dazzling array of applications and uses for nets, which force us to expand upon our preconceptions of what nets are and what they can be used for.

Pause for a moment – how many applications of nets can you think of? The late Frei Otto had a well-known interest in nets and their applications to structural engineering. A flip through a 1975 publication from the University of Stuttgart’s Institute of Lightweight Structures (of which Frei Otto was a director) reveals pages of sketches (see above and below) on net elements, forms, typologies, and applications. The applications range from the prosaic (tennis racquet, hammock) to the extraordinary (stadium roofs, bridges), to the bizarre (airplane barrier, anti-U-boat net).

Personally, my research concerns underwater cable nets, and I’m currently assisting with the design of a net with a very unique application: preventing shark attacks.

La Reunion, a French island in the southern Indian Ocean, is renowned for its surfing and beautiful beaches. However, this paradise has been suffering from a surge in shark attacks in recent years. Since 2011, there have been nineteen attacks, of which seven were fatal. The attacks peaked in 2013, which forced authorities to temporarily ban aquatic activities. As a result, the island’s economy has been strained, with beach-front businesses bearing the heaviest losses.

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“Net Out Of Order,” reads a sign on the empty Boucan Canot beach.

A solution to the shark problem soon arrived in the form protective nets, which were installed on the beaches of Roches Noires and Boucan Canot. At first, the results seemed promising, and other municipalities soon wanted to install such nets on their own beaches. However, it turned out that the conditions so sought by surfers were causing a significant level of wear and tear on the nets designed to protect them, meaning that the nets have been plagued by constant and costly maintenance issues. Then, on August 27 of this year, several holes were discovered in the net at Boucan Canot, prompting lifeguards to close the beach. Despite this, some people stayed in the water, until a young surfer lost a foot and arm to a bull shark. Since this accident, the beaches have remained closed, and the nets out of order.

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The net at Roche Noire, currently protecting nobody due to the swimming ban.

 

As part of my master’s project, I am developing numerical models to study the failure mechanisms of these nets and had the opportunity to work with Prof. Marcelo Pauletti (Sao Paulo University, Brazil), an expert in numerical modeling of non-linear systems and Prof. Adriaenssens (Form Finding Lab, Princeton University, USA). In early November, I had the opportunity to travel to La Reunion to see the nets myself, as well as to meet with Prof. Khalid Addi, an expert in contact mechanics (Reunion University, France) and Seanergy, the company overseeing the project.

The nets suffer the most damage in shallower waters, where breaking waves cause more movement. See if you can spot the problem areas in the video below:

In deeper waters, the nets experience less movement:

This visual evidence, along with my meeting with the company confirmed previous suspicions that a significant issue is fatigue and friction. Therefore, it is important to study the motion of the joints. I am currently working on a hydrodynamic model of the net using data collected from current profilers installed alongside the net at Boucan Canot Beach. Such a model describes how the net displaces due to the wave action, and should provide the necessary input information for a future detailed joint model.

After leaving the meeting with Seanergy, I drove down La Reunion’s historic Route du Littoral. (Learn about the current construction here.) This scenic coastal highway meanders along the base of steep cliffs and is notorious for constant closures due to rock falls. Besides the amazing views, one can’t help but notice the vast amount of rock retaining netting. After a 100 ton rock fall blocked the highway in 2002, authorities covered the cliffs with, of all things, anti-submarine netting salvaged after World War Two. Frei Otto’s more bizarre sketches no longer seemed so outlandish…

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A minor rock slide on the Route du Littoral, November 2016.

 

Author: Olek Niewiarowski

 

Grow strong and live beautifully: Colombian bamboo structures

While the new group of senior students are getting up to speed with their senior theses, we look back in this weeks blog post on the work of Russell and Lu Lu in Colombia.

In March 2016 Russell Archer (’16) and Lu Lu (‘16) traveled to the city of Cali, Colombia and the coffee region (Spanish: Eje Cafetero) north of Cali where they visited a variety of structures made of south American bamboo species Guadua angustifolia, known as the “vegetable steel” for its impressive strength. These structures range from traditional vernacular houses, roofs and bridges designed by Simón Vélez, to classrooms designed by Andres Bappler. Russell and Lu were inspired by both the abundance and the level of sophistication found in these bamboo buildings.

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Left Image: Russell (right) and Lu (left) standing in front of a huge bamboo forest near a school building construction site at UTP campus in Pereira, Colombia. Right Image: A vernacular bamboo chair in a local bar.

Visiting Cali, Colombia and the surrounding regions showed us how bamboo is deeply ingrained as a part of daily life in Colombia, from chairs and fences to larger scale bridges and buildings. Much of bamboo design is driven by designer’s and builder’s knowledge of the material properties. This knowledge has expanded over generations and has added to the scale of the structures that can now be achieved. At the Universidad Technolόgica de Pereira (UTP), an arch bridge designed by Simón Vélez (http://www.simonvelez.net/) traverses a roadway connecting two parts of the campus. He also designed the CARDER regional office. These bamboo structures are representative of emerging efforts to locally enhance the perception of bamboo as a building material. The efficient joinery techniques that incorporate mortar inserted into the poles and steel bolts, are indicative of the sophistication involved in the bamboo design.

3 View looking across the bridge deck at the Universidad Technolόgica de Pereira by Simón Vélez. The bamboo poles are covered with dark coating that protect them from sun and rain.

4 Russell (left) discussing the structural system of the arch bridge with DAGMA architect Daniel (right)

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Interior Corporaciόn Autόnoma Regional de Risaralda(CARDER) where inclined bamboo poles support the roof Exterior of Corporaciόn Autόnoma Regional de Risaralda (CARDER) with structural timber and bamboo poles

On the edge of the city of Cali, Montebello Colegio de Las Aguas, a school designed by Andres Bappler (http://www.escuelaparalavida.org/tag/andres-bappler/) and made out of bamboo, provides education to over 200 children living in this isolated town. Without the school, children would be forced to travel long distances over mountainous, narrow, roads for access to education. Transporting bamboo to Montebello was feasible given the material’s lightness. The classrooms go as high as three stories and feature bamboo poles utilized in very different functions, including beams and cantilevers, columns, trusses and ties.
7Montebello Colegio de Las Aguas (Three story main building) by Escuela para la Vida featuring concrete foundation supporting series of bamboo columns and bamboo pole roof supporting esterilla (split flat bamboo) and asphalt shingles.

8Montebello Colegio de Las Aguas (Larger bamboo hypar canopy along the walkway

9Montebello Colegio de Las Aguas (Walkway sheltered by various bamboo canopy roofs

10Montebello Colegio de Las Aguas (Open-air class room where the roof is comprised of multiple bamboo truss systems

On the highway connecting Armenia and Pereira is Peaje las pavas Autopistas del Café, we were astonished by this  toll booth structure designed by Simón Hosie (Washington Post Report). It is comprised of a series of tensioned rods and groups of connected bamboo pole columns, sitting on concrete piers.

11View of the steel tension tie and bamboo pole system in the canopy

12.pngView of the horizontal bracing in the toll booth

13As one looks up the concrete leg, the joints appear to be pinned and the poles change angles as one nears the canopy roof.

14Bamboo-steel joint connects four bamboo poles to the concrete leg

Authors: Russell Archer, Lu Lu

Photo Credits: Russell Archer, Lu Lu

 

The refreshing tandem: the works of the engineer Laurent Ney perceived by the visual artist Toshio Shibata

What happens when an artist photographs the works of a master designer and builder? The recently published book Toshio SHIBATA / Laurent NEY shows how the photographer Shibata sees the work of Ney, not for its engineering logic but for its inherent poetry. In this book Ney generously shares with us his views on bridge design alongside the visual artistic perspective of  Shibata.  A most unexpected and refreshing tandem.  We are grateful for this blog text which is the introduction to  the book, published with author’s permission. The book  further showcases hundred photographs of the work by Laurent Ney taken by the Japanese artist Toshio Shibata and can be purchased through this link.

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From Toshio SHIBATA / Laurent NEY – (August 19, 2016). Publisher: MER. Paper Kunsthalle.

Introduction

The design of a bridge starts with the context, a context that includes more than just the physical context of the site, its natural surroundings and landscape. A context in its broadest sense takes in historical, technological, industrial, economic, ecological and procedural considerations, all of which are subject to material and procedural constraints, which the project’s author must respect or, better still, transcend.

The work itself, the creative act, is the projection of the imagined object into the future context of the site. The insertion of this object will of course change the context of the site, as the object becomes part of the place, it becomes a place in itself, it becomes context.  The context or the landscape finds itself altered by this insertion, its reading is modified. One can ask oneself if this reading has been improved or not by it, but of course there is no definitive answer to this question, it is eminently subjective. This is where an outsider’s view, such as that of artist-photographer Toshio Shibata, can reveal a denser reality that can be read on various levels.

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De Lichtenlijn Footbridge, Knokke, BE ©Toshio Shibata for Laurent Ney, Design©Laurent Ney

There are a number of different things that I hold to be especially important in the design of a bridge:

 Scale

A bridge or a footbridge is an object that needs to work visually on a variety of scales. Firstly on an urban scale or within a landscape, where the observer reads the bridge in its entirety – a several hundred meter long sculpture in the foreground of a vista.  Next, at the scale of the user, the pedestrian, whose viewpoint evolves, who will touch the bridge’s materials, and who discovers the bridge via a shortened perspective of the journey in front of him. The bridge is no longer a simple linear extension of a route, but material, detail and viewpoint. It also becomes a place of passage, with all the associated symbolism of travelling from one side to the other, from one world to another. The pedestrian or the cyclist experiences the crossing as a passage across the void, no longer on solid ground, a space between the earth and the sky.

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‘t Groentje Bicycle Bridge, Nijmegen, NL©Toshio Shibata for Laurent Ney, Design©Laurent Ney

Time

A bridge links one bank to another, links people together, links the past to the future, a bridge has all the promise of a new world. The bridge’s spatiality is obvious, its place in time less so. I have always wanted to design with time, with the influence of time, its patina, its deterioration. A bridge that accepts time and alteration, or better still that uses time to transform it in a subtle way and to create a new way of perceiving it. I also wanted to show this slow return to nature, this fragile balance of stresses in a bridge, this potentially unstable stability, this retarded entropy – time, not as a problem but as a way of revealing other possible realities.

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Vroenhoven Bridge, Riemst, BE©Toshio Shibata for Laurent Ney, Design©Laurent Ney

Geometry

Space can be described through its materiality and its geometry. It is therefore natural that we would use these two guides in designing our bridges. An object is defined geometrically, exactly, and numerically. Mastering an object construction is about mastering its spatial description and, implicitly, its structure. Mathematics, physics, statics and natural phenomena come together, feed one another and transcend themselves in a built object.

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Smedenpoort Footbridges, Brugge, BE©Toshio Shibata for Laurent Ney, Design©Laurent Ney

Materiality

The other fundamental of a place is materiality; the bridge is built of materials that will lend their logic to the project. This materiality directly confronts the existing environment and its material make-up. Difference, resemblance, continuity or a clean break? The history of a built place is also the story history of its materiality.

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De Oversteek Citybridge, Nijmegen, NL©Toshio Shibata for Laurent Ney, Design©Laurent Ney

Poetry and symbolism

We strive to condense, concentrate and integrate our designs, removing the superfluous and concentrating on the essentials. However, this ‘simplification’ demands an increasingly complex process of analysis if we are to achieve the desired formal purity. Giving meaning, or better allowing the object to bear the meanings that people project onto it – a minimal object as a support for poetry.

In Toshio Shibata’s work I recognise the principal themes that are at the root of the design of my bridges: space, time, geometry, materiality, poetry…

There are similarities but there are also differences. A project’s author is a projector, he projects his thoughts into the future, he is at one end of the process. The artist-photographer is at the other end of the process; the object is completed, in its context, animated by the light. Light which ‘brings it to life’ and which, through a photographer’s eyes, allows us to see details that cannot be formulated, neither in plans, nor in figures, nor in words.

Laurent Ney

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Esch-sur-Alzette Footbridge, LUX ©Toshio Shibata for Laurent Ney, Design©Laurent Ney
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Vluchthaven Bridge, IJDock, Amsterdam, NL ©Toshio Shibata for Laurent Ney, Design©Laurent Ney
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Vroenhoven Bridge 2, Riemst, BE ©Toshio Shibata for Laurent Ney, Design©Laurent Ney

 

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What is the Optimal Shape for a (trussed) Arch?

Arch bridges date back to Antiquity. Steel trussed walkable arch (such as the one shown in the picture above) can be attractive because they can be prefabricated and thus speed up construction time on site. The deck can be cambered to either allow vertical clearance below and compensate for deflection under its own weight. However the maximum slope of the walkable arch is set by accessibility slope guidelines and needs to be shallow. Because of this shallowness, the arch is prone to in-plane snap-through buckling. This means that the arch can assume an inverted equilibrium position. Since the bridge is also lightweight, it natural vibration can coincide with the pedestrian-induced vibration as was experienced by the visitors to the Millenium Bridge on the day of its opening. When that happens, resonance occurs which can lead to severe structural damage.

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Illustration of arch snap-through buckling (Left) and resonance (right)

So what happens when we try to optimize the buckling or dynamic behavior of the walkable trussed arch bridge by allowing the nodes of the truss top chord to displace? The resulting truss forms, optimized in 2D (nodes only allowed to move in x,y plane) and 3D (nodes allowed to move in all 3 directions) are given in the table below.

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Optimization of the form of a trussed arch bridge by allowing the top chord nodes to move in the y and x direction (2D)

The resulting truss shapes all adhere to the slope guidelines and show a wide variety of forms including non-standard top chord topologies, global bow string topologies, tapered deck profiles and bowtie profiles in plan. When these optimized forms are evaluated for other structural criteria such as maximum axial member load and global deflection, all forms outperform the initial (in optimization called “ground”)  form.

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Walkable trussed arch bridge 2D and 3D optimized for buckling (first 3 rows), dynamic behavior (4th row) and stiffness (5th row)

When we start optimizing the ground form for different boundary conditions, a whole new realm of forms is revealed to us.  This research demonstrates that the right form can substantially improve the buckling and dynamic behavior of a walkable trussed arch. Much to our surprise, we found that the optimized forms also brought along substantial improved behavior for other less critical structural design criteria. However the take-home lesson is that even for a simple structural system like a walkable trussed arch, there is a whole wealth of superiorly behaving unexplored forms waiting to be built.   With these new forms, the vocabulary of the structural designer just got richer.

This post is based upon the work presented doctoral thesis ‘Stability and serviceability optimization of footbridges’ of my Ph.D. student Allison Halpern ’14.

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A whole wealth of walkable trussed arch forms optimized under varying support conditions.

Author: Sigrid Adriaenssens

Editor: Jacob Essig

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Mass Imperfections.

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The curved shapes of hand-made figurines are widespread in the Bethlehem’s tourism industry. What is intriguing about all these crafts is the precision of the forms given the basic tools used for their fabrication. An established hierarchy and apprentice curriculum maintains the artisans’ skills to a certain standard. Becoming an olive-wood master carver is, among other skills, being able to reproduce a complex-geometry shaped figurine while only looking at it.

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Olive wood artisan – Credits: AAU ANASTAS

The process of fabrication of olive-wood objects in Bethlehem calls high-tech mass customization into question. Mass imperfections is a project that experiments the potential of artisanal fabrication for the construction of large-scale structures.

The project experiments the ability of craftsmanship of stepping back into the forefront of the fabrication processes. Mass imperfections challenges high tech fabrication processes by monitoring and anticipating imperfections of highly skilled artisans.

The structure’s global shape is a 3m high arch made out of olive-wood pieces that are 1cm thick. The structure is made out of 552 mutually supported olive wood pieces that are small with respect to the entire structure. Each olive-wood panel has six vertices, three of which are supported by three neighboring panels while the remaining three support three other neighboring panels. In that sense, the structure is reciprocal; each panel plays an equivalent structural and topological role in the overall stability of the structure.

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Assembled panels. Credits: AAU ANASTAS

The global shape of the structure has been determined according to a process of design at the opposite end of the planning spectrum, from the bottom up. After several experimentations of faithfulness of an artisanal fabrication to a designed complex-shaped geometry, the level of imperfections has determined the family of possible panels and consequently potential global forms. The understanding and monitoring of imperfections helped merge into the deep understanding of local know-hows, and capacities of widening or subverting the initial end result to new uses.

Plan and elevation

 Olive wood has the particularity of being issued of branches thus avoiding the uprooting of the entire tree. The collected wood is of relatively small dimensions initially soaked with oil and water. Before it is ready for use, the wood is dried in hangars protected from exterior climatic conditions for several years. Once the wood is dry, it usually has a volumetric mass varying between 800 kg/m3 and 990 kg/m3. For the purpose of this project physical tests were held on dry olive wood in order to input our Finite Element Analysis (FEA) with the correct material properties:

The first concern of the structural analysis was to ensure the stresses in the panels were not exceeding the yield strength of the material, while our second concern involved the global buckling of the arch given its slenderness. The panels were defined as shell elements while their connections were free to rotate along the axis of connection.

The following diagrams show the values of axial stress in the structure and the displacement values. Although the thickness of panels is 1cm, their curved shape and the interlocking arrangement of the structure’s modules gives a 2cm structural thickness.

Material property Value
Density 0.92
Modulus of Rupture (MPa) 120
Compressive strength (MPa) 90
Tensile strength (MPa) 77

Utilization structural diagram and displacement structural diagram

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The fabrication of each panel has followed a long and slow process involving hybrid procedures of hand and machine controlled fabrication techniques. While a template panel was realized, the copy machine was the first step in duplicating panels, in batches of 12. The hand-powered movement of the 12-head copy machine monitors the movement of the artisan as a reference for the production of a batch of 12 pieces. As such each batch is an exact approximation of the original piece.

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12 head copy machine

Errors are embedded in the process of fabrication of the mass imperfections pavilion. Although it stands for the ability of low-tech to produce complex structures, it experiments a proposal of novel ways to blend the human and the machine.

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Credits: AAU ANASTAS

Mass imperfections is an olive-wood structure created for Dubai Design week 2016 — Abwab which opened on the 24th of October 2016.

A project by Local Industries (hyperlink: www.localindustries.org) X Scales (hyperlink : www.aauanastas.com), research department of AAU ANASTAS.

Author: Yousef Anastas

Yousef Anastas is an architect and structural engineer.
He holds a Master’s in Architecture from l’Ecole d’architecture de la Ville et des Territories (2011), and a structural engineering Master’s degree from l’Ecole Nationale des Ponts et Chaussées (2014). He is currently a PhD candidate at Geometrie Structure Architecture (GSA) research lab in Paris, working on the resistance optimization of stone vaults through advanced stereotomy. In 2014, he conducted a research at the Form-Finding lab of Princeton University on biomimetic building skins. In 2014, he was awarded the 40 under 40 award for young European architects. He is currently leading AAU Anastas’ research department, SCALES – a research laboratory that is consistently enhanced by linking scales that are otherwise opposed.

Revisiting a senior thesis: smart structures

Imagine having a lazy Sunday and laying out in the sun, but never having to get up and move your shade umbrella to a more optimal place throughout the day. This kind of technology is possible when structures and technology combine to make “smart” structures. Your umbrella could be a structure that senses the location of the sun through the solar panels on its covering, and depending on the amount of sunlight available, create optimal umbrella structure shapes for you.

How can this be done?

“Smart structures” are in fact highly possible. For my senior thesis at Princeton, I studied these adaptive sun shading structures, and my built model was composed of a pre-stretched dielectric elastomer adhered to an inextensible compliant frame. At a small scale, these built flexible models could furl and unfurl predictably. However, these built models were very small and labor intensive. What if there was a way to numerically compute possible “smart” structure shapes to more quickly iterate through different designs? In addition to verifying the built flexible models, I strove to understand if a computational method called dynamic relaxation could be employed for the analysis of dielectric elastomer minimum energy structures (DEMES).

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Photos of the DEMES structure studied

So can dynamic relaxation be employed for the analysis of DEMES?

The short answer is yes, it seems like it can.

Dynamic relaxation, a common structural form finding method, was chosen as a numerical simulation technique to simulate the curling action the DEMES. Dynamic Relaxation introduces a fictitious inertia and damping terms into the equations of motion, formulating a static system as the equilibrium state for a group of damped vibrations.

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DEMES equilibrium shape obtained with the dynamic relaxation model

Comparing computed shapes to the physically modeled stretched elastomer structures, there was a noted correlation between equilibrium angle and applied voltage for a biaxial stretch when using a modified Dynamic Relaxation algorithm with bending and clustered elements. Overall, while I found that a numerically modified structure is influenced by material uncertainties approximated input values, the Dynamic Relaxation technique was found capable of predicting the shapes and elastic energy of DEMES.

Much experimental work has been conducted on the potential of DEMES, and with the possibility of an easier computational method – Dynamic Relaxation – for numerically simulating its shapes and elastic energies, huge progress has been made for the reality of a “smart” sun shading structure. However, there are still many aspects of DEMES to be explored before its commercial reality, such as the differences in material strength of elastomer films versus sun shading umbrella material, or the effect of repetitive unfurling motion on DEMES material. Using Dynamic Relaxation techniques will allow us to iterate more quickly on different DEMES designs, and allow us to explore the potential of DEMES.

Author: Sabrina Siu

Sabrina Siu graduated Princeton in 2013 with a CEE senior thesis, ‘The Potential of Electroactive Polymers for Shape Shifting Structures,’ jointly advised by Professor Adriaenssens and Professor Sigurd Wagner (ELE). After Princeton, she worked for ExxonMobil Environmental Services Company as a Project Manager for 2 years, spending two years overseeing environmental clean up projects in the Midwest and the Northeast. After two years of Project Managing, Sabrina decided to change the trajectory of her career to refocus on the intersection of research and creativity, leading to her current position as a Digital Product Designer at a Media start up in New York. She is still fascinated in the relationship between the form and efficiency of built urban structures, and it’s her goal to one day contribute toward “smart” built structures.

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What I am thinking: Structural designer Jane Wernick

Jane Wernick is a British Engineer who has distinguished herself in the field of structural engineering. She has taught at Harvard University and has been the Chair of the Diversity Task Force of the Construction Industry Council, in addition to managing Ove Arup and Partner’s Los Angeles office from 1986 to 1988. In 1998 she founded Jane Werwick Associates Ltd., a superb engineering design consultancy which has worked on countless projects across the United States and Europe. I talked to Jane at the occasion of the Structured Lineages: Learning from Japanese Structural Design event, held earlier this year at MOMA. 

Sigrid Adriaenssens: You have worked with world-renowned architects, what is the value for you of working in a design team versus solo engineering?

Jane Wernick: I have only ever worked as part of a team. I very much enjoy the process of trying to work out and understand the aspirations of the client, architect and other consultants, and then trying to find structural solutions that support or even enhance those aspirations.

What objectives do you set for yourself when designing a structure? How would a trained audience recognize a structure designed by you?

I am keen to propose solutions that give delight, that are buildable and that give good value. As well as designing structures that are strong enough, stiff enough, durable etc. it is also important that, as engineers we appreciate what the structural elements will look like. For example, I think that a circular hollow section is likely to look much larger and heavier than a fabricated section with sharp corners. The triangular cross section is one of my favourites. This is what we used for the pylons of the Xstrata Treetop Walkway at Kew Gardens. Because we used weathering steel (because it didn’t need to be painted with an ‘un-natural’ colour) we couldn’t use rolled sections. And a tapered triangular cross-section was the most efficient we could use. It also looked more slender than the equivalent circular section would have appeared.

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South Elevation Xstrata Treetop Walkway showing the pylons
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Close-up Xstrata Treetop Walkway (Image credit LondonTown.com)

You once said “structural analysis is not a precise science, but difficult statistically; it is chaotic, and it is part craft” in the context of your work with the Fiat Team. This statement might seem upsetting to engineering students. Could you elaborate on this?

I think it is liberating. It means that there isn’t just one correct answer, and we can therefore inject a bit of art into the solution. I was talking about the fact that when we design a building we try to imagine all the worst loadcases and combination of those loadcases that might occur e.g. everyone standing on one half of the building at every level. Probably the building will never see any of those actual loadcases, and even if it did, we don’t actually go back and measure the stresses and deflections that occurred at that time. So it is as if we are designing for a parallel universe. We just know that by and large, if we follow through our logic, the buildings seem to perform o.k. The Fiat car project was a bit different. We considered a particular loadcase, of an applied torsional load, which represented one wheel being on the kerb. A full-scale prototype was made of the structure that we had analysed, and that load was then applied and the deflection measured. I think this is the only time in my working life that this has happened.

Communication between architects, engineers and the general public seems to have been important in your approach to advancing design projects. For example your hand sketches, your oral presentations and interviews and your written articles show a real talent to explain how structures are working, why a particular structure is being used and how that helps the design. How did you acquire these skills and why do you think they are important? How important is structural expression in your projects?

In order for good collaboration to occur we all need to trust and respect each other. I think as engineers we show our respect by assuming that the other members of the team will be able to understand what we are proposing, and why. We need to be able to explain ourselves. So we have to learn to be very straight forward in how we explain our solutions, and to keep on trying until we have got our message across. It isn’t always easy, and we don’t always succeed. But the best projects are those where we do all understand what the other is trying to achieve, and how.

Of course I am always happy when the structure is directly visible in the finished project. I like it if the observer can work out how it works. But there are also plenty of good pieces of architecture where the structural elements are not on display. My view is that in those cases the structure is like the bone structure in our face – It influences what we look like, but it isn’t the whole story.

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Jane communicates with architect Sarah Wigglesworth using drawings to describe options for the Chelsea Pavilion
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Chelsea Pavilion (image credit Jane Wernick Associates)

You have practiced in the USA, France and the UK. What are the similarities and differences in working in these varying contexts?

There may be differences in the ways in which projects are procured, how much time and money clients are prepared to pay for good design, difficulties with language etc. But in the end it is always the same – the best projects have the best clients, design teams and contractors who share a common goal.

How do you situate yourself in the tradition of British Engineering? (who were your teachers and role models, what do you bring that is different?)

I was very largely influenced by the words of Ove Arup, by the wisdom and advice of an engineer called Tony Stevens at Arups who was responsible for sorting out some difficult analysis problems with the Barbican Towers and Arts Centre amongst many other projects, and by Peter Rice. I’m not particularly interested in designing the worlds tallest or largest anything. I’m more concerned by our responsibility to the built environment. I want to be involved in projects that bring delight, and ideally that tread lightly on the planet. I enjoy being part of a multi-disciplinary built environment think tank called The Edge.

From your publication “Happy Architecture” and your involvement in the “Living Architecture” project, it seems that one of your personal core objectives is to improve the quality of life of people. Can you elaborate on that hypothesis? How do you think engineers can address the human crisis in Europe (eg. refugees, attacks, etc.)?

As part of RIBA Building Futures I edited a book called ‘Building Happiness, Architecture to make you smile’. It is a collection of essays about how the way in which we design our built environment might, or might not, affect our psyche. Certainly some project do bring a smile to our faces, others just make us feel comfortable. On their own, I doubt that they can make us feel happy, but there is some research that certain ways of planning buildings and open spaces can lead to higher levels of depression etc. People feel better if they think they have some control over their lives. If in some small way the way we design our space can assist this, then so much the better. As far as global security is concerned, it would be a shame if we had to build prisons around us to keep us safe. We need more than architecture to do that. I guess it comes down to good communications, trust and respect again. And let’s not forget a shared sense of humour too, if we can.

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Living Architecture, architect Nord, Structural Engineers Jane Wernick Associates

In 2015 you were made Commander of the Order of the British Empire. Why did this happen and why is this important?

I don’t really know why it happened. I guess someone put me forward, and then others supported the idea. It might be because I do other things than just straight forward engineering, such as being on the Council of the Architectural Association, and being a member of CABE’s design review panel. I was pleased that a structural engineer, who isn’t a ‘Captain of Industry’ got the award. It also gave me the opportunity to commission the design of a great hat.

What motivates you?

Collaborating with like-minded people and seeing things built.

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Sigrid Adriaenssens (Princeton University), Caitlin Mueller (MIT) and Jane Wernick (Jane Wernick Associates) earlier this year at the Structured Lineages event.

What is you greatest professional achievement and why?

I think it is starting my own firm, on my own terms, and the fact that we have contributed to a great collection of projects. More recently, it is the fact that I have found another lovely firm, engineersHRW, to take us over, so that I am not responsible for it all any more.

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Balancing Barn, a cantilever project by Jane Wernick Associates (image credt Jane Wernick Associates)
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The ringing singing tree (image credit Jane Wernick Associates)

What is your favorite structure and why? What did you wish you had done differently?

Well, I think the treetop walkway is my favourite project. We had a brilliant team and had a lot of fun.

It’s not really sensible to wish that I was someone else, as that will never happen. So I can’t really wish I had done anything differently.

What question do you never get asked but would like to be asked? What would be the answer?

I would like to say that I am not a single-minded person. I like to try to do lots of different things – making music, making things, gardening, snorkeling etc. I couldn’t imagine only being an engineer.

What is your advice to structural engineering students wanting to be structural designers?

If you want to be a structural designer you need to be both a good analyst and someone who is interested in the end product. If you can find lots of good ways to communicate your ideas your life will be easier. But the most important thing is to find a good working environment, with people who trust, respect and like each other.

 

Author: Sigrid Adriaenssens

IASS 2016: Out and about in Tokyo

Last week I had the opportunity to travel to Tokyo for the 2016 IASS Symposium, as one of the award recipients for the IASS design competition for an alternative New National Stadium. While I spent most of my time at the conference sessions, I still got to see many incredible structures while on a tour organized by IASS. Here are some highlights:

The Prada store by Herzog & de Meuron and Yakenaka Corporation features a lattice of H-sections that serves as both the lateral structural system and as the façade. img_0418img_0422

While on the tour, we got to see the Yoyogi Indoor Stadiums built for the 1964 Olympic Games. This was a very special visit, not because the 2020 Tokyo Olympic facilities were a major talking point at the conference, but because chief engineer Mamoru Kawaguchi was there to explain the project to us. At the time, Dr. Kawaguchi worked at Yoshikatsu Tsuboi’s firm, which designed the stadiums together with architect Kenzo Tange.

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Dr. Mamoru Kawaguchi explaining the design of the Yoyogi Stadiums

These two adjacent cable roof structures (one stadium for 15000 spectators and another smaller one for 4000) continue to be icons of 20th century architectural and structural design.

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Also on the tour, we visited the nearly-complete Roppongi Grand Tower, a 43-story tower by Nikken Sekkei Ltd. with a unique seismic design. Just below the Sky Lobby on the 29th floor is a “seismic isolation story” that features a complex arrangement of 161 rubber, steel, and oil dampers.

The U-shaped steel damper (above), obviously not designed to transmit any vertical loads, is supposed to deform plastically in the event of a major earthquake. Vertical loads are transmitted through the large rubber pads (green). These dampers connect to oil dampers (blue), which dissipate seismic energy as heat.

Also, the views of Tokyo were amazing.

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We finished the tour at the Tokyo International Forum, a convention center by Rafael Viñoly. The atrium features semi-circular steel girders that mimic the hull of a ship.img_0492

Overall, it was a great day and a great week in Tokyo!

Author: Olek Niewiarowski

Adaptive Reuse: How can we make old buildings more sustainable?

One of the most important tasks engineers face today is the design of sustainable structures. Through form finding, use of efficient and/or local materials, and external systems, a plethora of new environmentally responsible buildings exist today. These advanced structures seem to be the answer to reducing the building sector’s staggering carbon emissions, but what about old, historic architecture? What role do these buildings play in our sustainable future?

Tearing down all structures that aren’t explicitly sustainable isn’t necessarily best for the environment, as additional energy is required for demolition as well as construction of a replacement structure. Furthermore, these buildings also hold cultural and historical relevance, acting as roots that tie us to the people and virtues who came before. Old post offices, banks, schools, office buildings, and retail locations may never find their place in history textbooks, but their vernacular styles, as well as the people and events that populated their interiors, make them worthy of preservation. Sustainable design isn’t restricted to the environment; social and cultural sustainability should also be of our concern.

In order to understand how to best include these buildings within our sustainable agenda, it is important to look at their current environmental impact compared to most infrastructure found today. According to the National Institute of Building Sciences’ Whole Building Design Guide, “historic buildings are inherently sustainable.” Adaptive reuse of old structures not only ensures the maximum use of material lifespans but also reduces waste. These claims are corroborated by life cycle analysis (LCA) tests, demonstrating that “reusing older buildings result in immediate and lasting environmental benefits.”

Though these structures may not be as energy efficient as new high-tech ones, LCAs found that performance is not overwhelmingly compromised, as many existing buildings already have sustainable features. With the lack of significant climate control technology at the time of their construction, the form and materials of many old buildings were inherently efficient, trapping heat in the winter and releasing heat in the summer. Features include thick walls, shutters, overhangs, awnings, and high ceilings for air circulation and light admittance. Therefore, these sustainable features will be retained when rehabilitating and renovating them for contemporary use. Thus, with their waste reducing benefits, as well as their current level of performance, the best way to make old buildings sustainable is to use them.

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The original Frick Laboratory at 20 Washington Street. (Image courtesy of Denise Applewhite, found on Princeton University’s website

We can see adaptive reuse in action in the renovation of 20 Washington Street on campus. With the new Frick Laboratory (2010), this former chemistry building became obsolete. However, with its central location and “iconic collegiate gothic structure” that ties it to the rest of campus, 20 Washington Street is too significant to demolish, Shirley Tilghman, president emerita of Princeton explained while she was in office. Thus, the university decided to transform the building into the new home of the Department of Economics and the university’s many international programs and services, which are currently sprinkled across campus. With the help of Kuwabara Payne McKenna Blumberg (KPMB) Architects of Toronto and engineers Thornton Tomasetti, the renovation will focus on “[striking] a delicate balance between preserving the most appealing features of this building—its stone walls, wood-beamed lobby, leaded windows, and collegiate-gothic flourishes— and transcending its limitations—a gloomy interior, mazelike corridors, and a woefully inefficient mechanical system.” Essentially, the project involves maintenance of the gothic exterior, with a reimagined interior that is light, airy, and contemporary. Primary interior spaces, such as the entryway onto Washington Road and the second-floor library, will also be preserved. The only exterior addition will the entrance onto Scudder Plaza, which serves to separate the two departments housed.

Perspectives view of Southern Atrium, at the entrance to Scudder Plaza and interior perspective views (Image courtesy of KPMB Architects)

The renovation meets LEED Gold Standards with its reuse of a historical structure, including reuse of materials such as the stone exterior and interior woodwork, use of sustainable materials in finishes, stormwater management, and energy efficient temperature, lighting, and plumbing systems. The project is admirable as an act of sustainability and preservation. From this project we can see not only the feasibility and success of adaptive reuse, which can bring together a campus, supplement present sustainable features of older buildings with new technology, and allow for the modern and historic to exist in one structure.

A couple elements of the project prompt further thinking. Architecturally, what should the visual relationship be between the historic exterior and contemporary interior? Should there be connectivity, so that one experiences both the old and the new for a fuller experience of the building and its history? The reuse of wood and stonework seems to bridge this gap to some extent, and it will be interesting to see how detectable this link is when occupying different spaces. Or perhaps the exterior and interior should be experienced separately, such that the two distinct lives of the building are easily perceived? Structurally, how were the forms for the additions and renovated interiors chosen? Could large elements, like atriums, benefit from form-finding to make them more efficient alongside external systems and material choice? How can we create a form that is both environmentally friendly as well as achieves the desired architectural experience? These are all questions we need to consider in the adaptive reuse of buildings for sustainability and preservation purposes, and upon its completion this year, it will be exciting to see 20 Washington Street’s solutions to them.

Author: Katie Kennedy ’18

Sources:

https://facilities.princeton.edu/projects/20-washington-road-economics-and-international-buildings

http://www.kpmbarchitects.com/index.asp?navid=30&fid1=&fid2=127&fid3=&minyearx=&maxyearx=#credits

https://paw.princeton.edu/article/transforming-20-washington-road

http://www.princeton.edu/main/news/archive/S39/15/61O35/index.xml?section=topstories

https://www.wbdg.org/resources/sustainable_hp.php