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:

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

4th of July and NYC bridges and towers

Brooklyn bridge lit up by fireworks

It is the 4th of July, a Holiday in the USA so no extensive blog post! We are watching the long span bridges and the tall buildings lit up against the fireworks.  Happy Holidays to you!

Empire State building lit up and fireworks!
bayonne bridge.jpg
Bayonne Bridge
George Washington Bridge

5 Movies You Must See as a Structural Designer

The summer holds the promise of long summer days and warm summer nights.  We can imagine nothing better than watching a movie outdoors under the stars. So there is no better time to present our 5 movies you must see as a (budding) structural designer.

Structural design and cinema seem to have little in common.  Structural designers create and realise long span bridges and towers that take us over waterways or shelter us from the elements.  Cinema is but an illusion, built on the phenomenon that our eyes perceive a series of still frames as a moving image.  Cinema is the make belief of structures.

However in same way structures and cinema are also similar.  Both rely on large teams of experts to realize a large budget project on time under the leadership of a director or the project designer. And both create three-dimensional spaces,  real or as an illusion.

The movies our team at the Form Finding Lab has chosen, are a personal selection; they are movies that have stuck with us.  They each feature ordinary and spectacular –real and imaginary- structures. Some are real,derelict and glorious, some rely on computer graphics, some use minimal amounts of materials but they are all awesome.

  1. Infrastructure (John Oliver, 2015)

“Infrastructure is like Legos,” says John Oliver “Building is fun, destroying is fun, but a Lego maintenance set would be the most boring fucking toy in the world.”

John Oliver demonstrates the sorry state of America’s neglected infrastructure includes that“hold your breath” bridges, killer potholes, a severe lack of inspectors and potential floods from our half-century old dams.  At the end of the movie Oliver presents a trailer for a new summer blockbuster movie about fixing cracks and less about explosions featuring our favorite actor Steve Buscemi.

Oliver makes us laugh amidst despair.

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  1. Unfinished Spaces (Alysa Nahmias / Ben Murray, 2011)

After the revolution, Fidel Castro ordered the National Art Schools to be built on the site of a country club, a move to enrage wealthy capitalists.  The post-embargo material shortage resulted in the curved thin shell brick shell of the School of Modern Dance, designed by Ricardo Porro.  This shell reflected the sensuality Castro thought to be unique to the Cuban spirit. While four other schools were planned, the School of Modern Dance was the only one to come close to completion when Castro pulled funding from the entire project in 1965.  The movie “Unfinished Spaces” draws attention the restoration movement of this shell and its fate.

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The National Ballet School by Vittorio Garatti (image credit:



  1. Hogwarts Great Hall (Films 1-6, 2001-2009)

The design for the Great Hall set in the films was based on the dining hall at Christ Church, Oxford and reminds me of our Princeton Graduate College Proctor dining Hall. The movie set can be visited outside of London (it’s open to the public). Computer graphics were used to create the vaulted structure we see in the movie.

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The architecture of the dining halls as depicted in the films (photo credit:


  1. El arquitecto de Nueva York (Eva Vizcarra, 2015)

This Spanish documentary reflects on the life and work of the Spanish-born architect and builder Rafael Guastavino Moreno (Valencia, 1842). Guastavino and his company designed and build Catalan (also now referred to as Guastavino) vaults for prominent buildings in New York such as the Carnegie Hall, the subway station City Hall, the Cathedral of Saint John the Divine or the Queensboro bridge. Rafael Guastavino died in 1908, but his son Rafael Guastavino Expósito took over the business of his father. Guastavino Company closed its doors in 1962 as they were not able to compete with the lower-cost concrete shell structures. This documentary tells the story of Guastavino’s life, the structures he built and how the New York Times referred to him as “the architect of New York” in his obituary.

Grand Central, Oyster Bar with Guastavino Vaulted Ceiling (credit eater New York)



  1. My Architect (Nathaniel Kahn, 2003)

Nearly 20 years after world renowned architect Louis Kahn died from a heart attack, his son, Nathaniel Kahn, documents his findings after embarking on a journey to gain a better understanding of who his father was. Being only 11 years old and being raised mostly by his mother when his father died, Nathaniel had only a hazy idea of who his father really was. Although the movie is centered on this emotionally-driven quest, it offers insights into the works and designs of Kahn. Design aspects of his buildings are explored, along with the religious and philosophical background to the choices he made in his designs.

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Louis Kahn’s Salk Institute (photo credit: cam-salk-institute-louis-kahn-20161107-htmlstory.html



StoneMatters: a new future for Palestinian stone

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. In 2014, he conducted a research at the Form-Finding lab of Princeton University on biomimetic building skins. He was also 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.

Recently, Anastas completed a project in Jericho, Palestine where he focused on resistance optimization of stone vaults through advanced stereotomy.

Stone as a construction material in Palestine

Historically, stone has been the most common building material in Palestine. It is abundant, and its use in construction was in fact mandated by the Ottomans in order to unify the landscape. As a result, the stone is not only a marker of the transition of urban and social structures, but also shows the evolution of Jericho’s morphology. The construction techniques’ evolution thus had an effect on the entirety of the Palestinian city.


Palestine suffers of a misuse of stone as a structural material: while it was an abundant material used for structural purposes in the past, it is now used as a cladding material only and the know-how of stone building is disappearing.

The research aims at including stone stereotomy – the processes of cutting stones – construction processes in contemporary architecture. It relies on novel computational simulation and fabrication techniques in order to present a modern stone construction technique as part of a local and global architectural language.

Our research department – SCALES – and GSA (Geometrie Structure Architecture) lab are leading this research on stone construction techniques. The results of the research will be used to build the el-Atlal artists and writers residency in Jericho. As such, Stonematters is the first module of the residency and the first built vault of our research.

Stonematters is built on an innovative construction principle allowing for unprecedented forms for such structures, born from morphology – the study of the form of objects – and stereotomy. The vault itself covers a surface of 60 m2 and spans 7 meters with a constant depth of 12 cm. The geometry follows the shape of a minimal surface on which geodesic lines are drawn and set the pattern of the interlocking stones. The whole structure is made of 300 mutually supported unique stone pieces.

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1. Top View. 2. Axonometric view

Aside for the technological issues which make Stonematters a unique design, cultural barriers were also encountered; the entire project was built using existing local techniques from the culturally marginal city of Jericho. Processes from several factories were combined so as to employ known methods for new uses. Hence, the research bids at linking construction techniques to urban morphology. It puts a non-hierarchical hypothetical link between the scale of stereotomy and the scale of urban fabric. In that context, the idea is to suggest new urban morphologies linked to the scientific use of a largely available material in Palestine.

The Process

Cutting the stone

The geometry of the vault follows the shape of a minimal surface on which geodesic lines are drawn and set the pattern of the interlocking stones. Each stone has 4 inclined interfaces, that allow the assembly of the different stone voussoirs. Based on geometrical parameters as the overall shape, the density of the paving, the inclination of contact surfaces, the size of the voussoirs, and number of voussoirs types, a specific structural criteria can be improved.

Creating formwork

In order to lay out the stones, a series of polystyrene blocks of differing heights were carved to create formwork for the stones.

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Polystyrene blocks are moved into place

These blocks of polystyrene were arranged in the form the vault was to later take shape. These blocks were placed on top of wooden framework, which was later removed with the blocks once the stones had been laid and interlocked.


While the polystyrene blocks were digitally cut using robots, the wooden framework was all constructed by local artisans using traditional methods.

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This image shows the entire formwork system at work: the wooden scaffolding supports the polystyrene blocks which keep the cut stones in place as the vault is being constructed.

Mounting the stones

Stone voussoirs are assembled on the mounted polystyrene blocks. Each stone’s location is defined on the formwork. The mounting started from the upper center of the vault progressively advanced towards the edges in a concentric process. The inclined interfaces between the stone voussoirs generate the interlocking system of the structure.

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Finished Product

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The el-Atlal structure is a model of the concept, which envisions a new construction method. The model allows for new morphologies, construction techniques and uses for a widely available construction material. The project has the ambition of creating a mode of urbanism; one whose scales are profoundly associated, one whose technique and durability leaves a trace on the city’s evolution and on the Palestinian landscape.

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The design for the el-Atlal consisting of twelve interconnected vaults using the Stonematters construction technique


Author: Yousef Anastas

Editor: Emre Robe

Water, Wood and Temperature: Hygroscopy at its best

When the relative humidity in the air increases, wood increases in volume as the water molecules become suspended between the wood cellulose fiber molecules.  In wooden laminates made of different wood species, grain orientations or thicknesses, this phenomenon can cause  fascinating shape shifting forms as the different wood layers start interacting.

The goal of final project of  course CEE546 “Form Finding of Structural Surfaces”  was to tailor the hygroscopic behavior of wood for the design and construction of a shape-shifting façade panel. Such a panel could be incorporated in an adaptive building skin.The purpose of adaptive building skins is to actively moderate the influence of weather conditions on the building’s interior environment. Current adaptive skins rely on rigid body motions, complex hinges and actuation devices. These attributes are obstacles to their broader adoption in low-carbon buildings. This project explored these challenges and solutions. The core idea of hyrgoscopic adaptive skins is that they exploit the inherent swelling and shrinking wood properties to change their shape and respond to external weather conditions of changing humidity and temperature.

A number of  projects, physically and numerically developed and prototyped by teams of graduate engineers and architects in the Spring of 2017, are presented here.

Project 1: The aim of the project was to understand the behavior of a tri-layer adaptive wood facade subject to different configurations of the active and resistive layers. We performed both numerical and physical experiments to achieve the same and the results from both were compared for validation. Understanding the behavior in different configurations will help us use the optimum one for specific purposes. (Ryan Roark, Vivek Kumar, Emma Bonintende and Andrew Percival)



Project 2: The motivation of “The Wave” was to create a shape-shifting hygroscopic panel without the use of outside actuators that would be able to respond naturally to weather events, providing appropriate ventilation and lighting while presenting the ebb and flow of an ocean wave. The goal of the sliding panel was to create waving openings during sunny dry weather but to flatten closed during rainy or humid days (Peter Wang,  Laura Salazar, Jedy Lau and Myles McCaulay)




Project 3: The goal of our project was to create a shape shifting façade which opens and closes as if it were a flower. Given diamond shaped flower units, the types of wood, and the thickness of both the active and passive layers, we optimized the height of the triangular petals and the grain orientations of both the active and passive layers of façade to ensure the flower petals not only meet in the center but also maintain reasonable stress levels. ( Ivy Feng, Doris Avit, Andrew Rock)




Project 4: The facade system is conceived as a temperature moderating outer skin that provides shade and ventilation for a building or public space in a hot, arid climate. Utilizing the shape-shifting properties of wood veneer, the facade panels curve when exposed to moisture and relax when dried. The project reconsiders the dynamic facade as a system that functions through an inherent material intelligence rather than a mechanized assembly. The project further considers the possibility of utilizing vegetation or man-made water features in concert with with diurnal temperature changes to provide the necessary humidity to allow the facade to open and close through the course of a day and adapt seasonally to variations in weather and solar gain. (Veronica Boyce, John Cooper and Devin Dobrowolski)

Wood Sample Matrix



Project 5: We used this project to explore the effects geometry and grain orientation had on the hygroscopic properties of wood. We tested different ratios of triangle shapes and either parallel or perpendicular grain orientation between two layers of wood and compared the stresses and deformed shapes to optimize the shape. (Annie Levine, Sean Rucewicz)



This project was made possible through the William Pierson Field Fund and the  Bartlett Funding  with the collaboration of Prof. Gabriele and Luigi Olivieri (Roma Tre University, Italy) and Prof. Abdelmohsen and Rana Ahmed Bahaa (American University of Cairo).

What I am thinking: bio-inspired engineer and artist Bill Washabaugh

Bill Washabaugh is an artist, aerospace engineer, roboticist, designer, and maker. Bill is the founder of Hypersonic Engineering & Design, a firm in NYC working at the intersection of technology and art. He has designed flight control software for Boeing, music instruments for Bjork, and a massive stage show for U2. Trained as an Aerospace and Mechanical Engineer, he pushes the boundaries of the art of engineering through an impressive variety of projects.


Sigrid Adriaenssens: Why and how do you study processes and patterns in nature?

Nature, or natural selection, has figured out so many incredible design solutions that work so well.  It’s our best resource for finding out what works well, and lasts a long time.   I think we’re predisposed, by way of our co-evolution in/with the natural surroundings, to find natural forms as beautiful.  The fact that we’ve been able to use science and math to put logical relationships to these beautiful forms is magic to me.  The diversity of ways in which nature takes form – at the macro, micro, scientific, and mathematical– makes for a pretty endless diversity of study.  How we study it is somewhat haphazard: it’s just through random inquiry, talking with colleagues, reading, and keeping our senses open to surprise and ready for inquiry.

In your design approach, you emphasize interaction, beauty and movement. Why is that important to you and to society?

Our work is really about people.  That’s a critical point in our process.  How does a piece make the viewer feel, how does it pull them, what might they remember, what’s the viewpoint, what’s the reference, what’s the process?  We are interactive beings, so we like to keep in mind that there is always a give and take, a call and response.  I think the movement of our works lends itself well to that, because it evolves over time and can offer an experience that is changing and at times, unexpected.  I think it’s important to pull people in with something beautiful, and try to inspire them to wonder about what they’re seeing, and ask them to investigate that and learn something new.

What is the importance of making in your work?

All of our works are physical objects, and each one we do is a new process, so making is a huge part of what we do.  Our team believes strongly in the need to escape from the screen in both the design process and final viewing experience.  We do spend a lot of time designing and coding on the computer, but holding and shaping and walking around the form is super important, that’s how it will be experienced. As well, because so many of our works involve complex physical movements, we spend a lot of time putting together physical prototypes to see what works and what doesn’t, and how things actually move in real life.

How do you choose your collaborators?

We’ve got a great group of friends that we often call on.  It’s a very organic process, and changes with each project.   We’re also really lucky to be based out of a studio in Brooklyn that we share with a really diverse and talented set of people.  We’ve got big data scientists, creative coders, costume designers, biologists, and more.   It’s the diversity of expertise and input that often leads to new directions and ideas that are so much fun.

What is your greatest (professional) achievement and why?

Getting to work with an incredible team of good friends every day.

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

Actually, I think the previous question is probably it.

Plenty more stunning projects by hypersonic can be found on their website,

What to see when visiting Princeton, USA: Guastavino Vaulting

The famous Princeton Reunions are coming up this weekend and many guests will reminisce and celebrate their student years with us .  But few of these guests will know about the Gaustavino vaults hidden between the neo-gothic architecture, typical of our Campus.

Much has been written about how Rafael Guastavino introduced this original Catalan Vaulting technique to the United States of America at the end of the 19th century [1].  The technique goes back to the 14th century in the city of Valencia. The Spanish king Pedro IV encouraged his masons to travel from Madrid to Valencia to learn this new technique to constructs vaults that were “Very profitable, very lightweight, and very low cost work of plaster and brick”[2]. The concept of this construction technique is to interlock tiles with layers of fast-setting mortar to make a thin skin.  Many centuries later the Spanish architect Rafael Guastavino (1842-1908) would bring this technique to North- America.

Figure 1: 1910 Patent for a Guastavino Vault Structure (left) , and Rafael Guastavino (right)

When trying to understand Guastavino’s decision to migrate from Spain to the United States of America, it is important to assess the impact that the socio-economic context of the time had in it. It is important to note that Guastavino was a respected architect in Barcelona. Spain in the 19th century experienced tumultuous period. During these years, the political situation was never stable. The change from the Ancient Regime to the liberalism was not easy. King Alfonso XII ascended to the throne in 1875. He was a popular king and was able to qualify the monarchy again. Being a male was enough to calm down the Carlists, who had been fighting against his mother, Queen Isabel II, for the last 40 years. However, the situation in the country forced many people to emigrate to America. The period between 1882 and 1930 was marked by a deep depression. Around four million Spaniards emigrated to America between 1882 and 1930. Usually, before a period of recession starts, there are some years in which economy stabilizes and does not grow. Guastavino’s family moved before the actual depression started, but they were showing the path to many Spaniards that will move later.

In the United States, the situation was completely the opposite. East coast cities were starting to develop and overpass the European metropolis. Guastavino saw in the new development a great chance to export his technique of tile vaulting. A new era of industrialization was taking place around these cities. The country was being expanded rapidly towards the West Coast as well so, new cities would be created.

One can say that Guastavino made a brave decision when choosing a country with such a different culture and language, which he did not speak at the moment of his arrival, when he could have chosen any other Spanish speaking country such as Argentina or Uruguay where many Spanish emigrants moved to. Guastavino put his career ahead of his personal comfort. He was able to evaluate the different possibilities and choose the most appropriate to develop his job.

For your visit to the Princeton Campus, we have identified no less than three Guastavino Vaults.mapPrinceton

Figure 2: Campus Map showing the location of Gaustavino Vaults

Class of 1879 Gateway

The Class of 1879 Hall was designed by the architect Benjamin Wistar Morris Jr when the President of the University was Mr. Woodrow Wilson, who would become later the President of the United States. Guastavino’s main contribution was the tiling of main arched pathway under the tower. The vaults are built with bricks, and completed with stone ribs to provide stability.


Figure 3: Princeton University Class of 1879 Guastavino Vault

Princeton University Chapel

Princeton University Chapel was built in response to the fire that destroyed the previous Chapel, Marquand Chapel, in 1920. The president of the University at that time was Mr. John Grier Hibbe. The design was based in 14th Century English Gothic style. The University appointed Ralph Adam Cram as the architect for this project, the leading Gothic revival architect of the early 20th Century. The building was completed in 1928 and it costed $2 million, which was a significant amount of money in that time.  Even though the main vault was not designed by the Guastavino Company, some auxiliary vaults, not open to the public, were built by them. The main vault is built, according to the plans, out of cohesive tile. It is reinforced with ribs that meet in the center point of each individual bay. These ribs help the vault to stay stable.


Figure 4: Princeton University Chapel Vaults (image credit Princeton University)

Patton Hall Entrance 

We have little information about the construction history of the Vault in Patton Hall.  The Hall  was first occupied in 1906, so it was built probably between 1900 and 1905. When visiting, one sees the thickness of some tiles and the mortar between two rows of tiles, the typical shape of the Gaustavino Vaultand as well as the arches between the two vaults. This arrangement of arches can also be found in the Boston Public Library, for example. Finally, the artistic pattern in which the tiles are placed is characteristic for the work of  Guastavino.


Figure 5: Azul tiling in a herringbone pattern at Patton Hall.  This pattern can also be found in the Guastavino Vaults at the Grand Central Oyster Bar in NYC.


[1] J. Ochsendorf. Gaustavino vaulting: the art of the structural tile. Princeton Architectural Press, 1st edition, 2010.

[2] P. Araguas. Butlleti de le Reial Academia Catalan de Belles Arts de Sant Jordi, 1998. Extract from “Rey Pedro IV de Aragon a Merino de Zaragoza el 20 Junio de 1382”, from Archivo de la Corona de Aragon.

Author: Lazaro Luis Vallelado

Editor: Sigrid Adriaenssens

Sun, Water and Shapes

“Water is essential for life, health and human dignity” World Health Organization

In a previous post Dream Big: Engineering our world, we showed a video of our students designing and constructing a water supply system in Peru with Engineers without Borders.  In our CEE 546 Form Finding of Structural Surfaces Course, teams of engineering and architecture students were challenged to develop the shape of a membrane so that it channels rainwater into a 2 or more storage shipping containers.  The membrane water harvester is meant to double up as a shading canopy for a small community.

Figure 1: Inverted conoid membranes with interesting seam layout pattern. (project Laura Salazar, Ryan Roark and Annie Levine)

The entire design would preferably be demountable and fit within the container (to be transported and deployed elsewhere). Such a deployable low-cost system, would aid temporary or permanent recovery efforts in disaster struck areas, cut-off clean water supply.

Figure 2: An assymetric membrane conoid configuration with a ring hoop connection at the top of the mast to reduce stresses in the membrane. Sun and rain shading studies for one and a coupled module (project Veronica Boyce, Emma Benintende and Dorit Aviv)

For this project the students experimented with physical form finding techniques using a flexible fabric such as lycra as well as a numerical form finding technique based on the force density method to arrive at and fine tune their shapes.


Figure 3: Spline stressed arch supported membranes with an elegant solution to ensure the stability of the  boundary arches.  Active bent arch spans in the order of 25m and is stabilised from buckling by the pre-stressed membrane. Cross-ventilation envisaged (project Devin Dobrowolski, Andrew Percival and Andrew Rock)

The generated shapes drew upon the 4 archetypal membrane forms: the saddle, the ridge and valley, the conoid and the arch supported membrane system.  The students steered their forms to have sufficient anticlastic curvature for stiffness and rainwater flow.  They also paid attention to appropriate membrane and edge cable pre-stress levels and connection detailing.

Figure 4: Ridge and valley system poses a great challenge to achieve anticlastic curvature in the membrane.  This curvature is achieved here by positioning the supports close together and having a substantial height difference between the low an high points. (project John Cooper and Vivek Kumar)

Figure 5:  A variation on the saddle shape. (project Peter Wang, Miles McCaulay, Jedi Lau and Ji Shi)

Author: Sigrid Adriaenssens


Exhibition: Creativity in Cuban Thin Shell Structures

After the revolution, Fidel Castro ordered the National Art Schools to be built on the site of a country club, a move to enrage wealthy capitalists.  The post-embargo material shortage resulted in the curved thin shell brick shell of the School of Modern Dance, designed by Ricardo Porro.  This shell reflected the sensuality Castro thought to be unique to the Cuban spirit.

School of Modern Dance image credit: Paolo Gasparini

While four other schools were planned, the School of Modern Dance was the only one to come close to completion when Castro pulled funding from the entire project in 1965.  The movie “Unfinished Spaces”  draws attention the restoration movement of this shell.

The shells of the National Ballet School and the National Dramatic Art School are two of the six thin shell project highlighted in the exhibition “Creativity in Cuban Thin Shell Structures”, currently on display in the Friend’s Library at Princeton University.

The National Ballet School by Vittorio Garatti (image credit
Plan view of the National Ballet School image credit images.adsttc

The models presented in this exhibition were made by students in the course CEE 463 A Social and Multi-dimensional Exploration of Structures.  By focusing on the Cuban shell designs (National Ballet School, National Dramatic Art School, Parque Jose Marti Stadium, Nunez-Galvez tomb , Arcos de Cristal and Tropicana entrance Canopy) the students made engineering analyses and examined the socio-political context in which the shells were realised.  In one of our next posts, we will show how that Cuban shell zeitgeist influenced one of the most iconic thin shell structures in the United States of America.

Arcos de Cristal Image credit

Author: Sigrid Adriaenssens