What I am Thinking: Reflective Practitioner and Educator Eric Hines

“The two worlds of practice and teaching are hard on each other. To live between them is kind of hard because you get pulled in both directions and don’t get a lot of sympathy from either side. I’ve learned how to be flexible and strong in certain ways by running between the two,” Prof. Hines says. “Going into it, I had more literal expectations: ‘let’s do some research, let’s advance the state of the art, let’s teach the students about our buildings’. But the good stuff is a level down from that: it’s about the people, how we understand things, how we do our work, how we fail and recover, how we succeed, and how we support each other.”

Tufts University Civil & Environmental Engineering Professor of the Practice Eric Hines takes one of his classes on a tour of the building projects his company was working on in Post Office Square. Photo: Tufts University

I first heard of Prof. Eric Hines as a rising sophomore at Princeton working with Prof. Adriaenssens in building on her existing Mechanics of Solids course. At the time, we drew much inspiration from Prof. Hines’s compelling pieces of writing on education and creativity in engineering, such as his series “Principles in Engineering Education” and his essay “Understanding Creativity.”

It is no coincidence that he wrote for and co-edited the Festschrift Billington 2012, a series of essays written in honor of Princeton Civil & Environmental Engineering Department’s Emeritus Professor David Billington; Prof. Hines was a graduate of the Princeton CEE Department himself. It was thus inspirational to meet Prof. Hines last week at Tufts University, where he has taught since 2003. As Professor of Practice in the school’s CEE department, he divides his time between Tufts and the LeMessurier engineering office in Boston.

Being in practice has forced Prof. Hines to think carefully about what he brings to the classroom. He expressed frustration that while the theoretical examples presented in textbooks are useful in helping students grasp concepts, “when you’re working in the real world on design, the real world doesn’t divide itself neatly up into little ideas.” In real problems he encounters in practice, “the ideas are important for understanding, but all these wild things happen: they intersect and pull over on each other, they become complex and even ironic in their intention… In the classroom, I like to have a real example, but the real examples are messy and difficult, and it can be hard to turn them back into theory.”

Continue reading “What I am Thinking: Reflective Practitioner and Educator Eric Hines”


A Physical Costa Surface 3/3: Building the structure

The fabrication of a tensile structure is a complex design process. How can the mathematical shape and the form found geometry derived in the first and second parts of the series be used as the basis for a sculpture? In this final post of the “Physical Costa Surface” series, the Costa Surface sculpture takes shape.

The dimensions of the sculpture are 1.5m of height and 2m of diameter. In order to build the sculptural installation, four steps are necessary: patterning the surface, designing the interaction between compressive and tensile elements, cutting the fabric and assembling the pieces.


Thread direction in fabric – the warp direction is often prestressed during manufacturing

The first task to making this surface a physical reality is patterning. This operation is maybe the single most important in the design process. The success of the patterning will in part determine if the tensioned surface will wrinkle or not. Fabrics used in engineering projects have generally a high level of anisotropy with warp and weft directions of the weave determining the material properties. In loom manufacturing, the warp direction is generally pre-stressed while the weft is weaved. In our case we used a high quality nylon/spandex fabric presenting a four-way stretch (ideally equally stretchable in warp or weft). The fabric can accommodate large strains so the risk of wrinkling is minimized.

We performed the patterning on the initial mesh geometry of the form finding procedure (details can be found here). In this process three distinct patterns are produced. The figure below shows how the patterns are distributed over the surface. The patterns are shrunk to compensate for the pre-stress and large strains in the membrane.

Patterning of the 6-hole Costa surface

Interaction tensile / compressive elements

The visuals of the structure have been so far limited to the surface itself. The constraints of the mathematics are fixed boundary conditions. The constraints of the fabric impose the application of the tensile stresses. These will in turn modify the position of the boundaries.

In order to create rigid circular boundaries, 3/8in. (9.5mm) glass fiber reinforced plastic rods were used. They were bent into 1.5m  (top and bottom) and 2m (center)  diameter circular hoops and connected by aluminum sleeves (ferrules).

The top and bottom rings are equilibrated by bending active GFRP rods. As seen in the figure below, by being bent, the rods push the two rings apart. The actions of the rods are equivalent to the thrust of an arch, providing the necessary force to achieve a height of 1.5m as specified in the computational model.

Building the sculpture

Continue reading “A Physical Costa Surface 3/3: Building the structure”

Design-and-build bamboo shells

Bamboo is a building material that lends itself excellently to the construction of sustainable gridshells. Two of the Form Finding Lab’s graduating senior students, Lu Lu and Russell Archer (’16), worked under the guidance of PhD candidate Tim Michiels and Professor Adriaenssens on the analysis of a set of hyperbolic paraboloid (hypar) gridshell roofs in Cali, Colombia. The Form Finding Lab’s team collaborated closely with the design team of Colombian-based Spanish architect Greta Tresserra and her team to improve the structural understanding of gridshells made from locally sourced bamboo. Follow Lu Lu and Russell’s adventure in this video:

Senior thesis: Sustainable building with bamboo from Princeton University on Vimeo.

Bamboo Gridshell Hypar in Montebello, Colombia

Colombia is home to the giant American bamboo species Guadua Angustifolia. Guadua, a type of grass, can grow up to 18m tall and obtain its full height in a mere 6 months. Moreover, it can be harvested and treated for construction purposes after 4 years requiring relatively little effort. The speed of growth of bamboo and the ease of its harvesting is in stark contrast to the time and resources that are required to obtain wooden lattices, a typical material used for gridshell construction. Moreover, architect Tresserra only employs traditional, low-tech joint techniques in order to make expressive and elegant guadua construction accessible to less affluent communities.

Guadua bamboo culms are straight hollow tubes with interspersing nodes about every 20 cm along its length which act as diaphragms. The guadua tubes are thicker than typical bamboo poles, which makes them much stiffer, which is why it makes most sense to employ these straight poles as rectilinear elements in construction. Hypar surfaces, revolutionized by Felix Candela in his concrete shells in Mexico, can be made out of just straight elements, allowing for an elegant forms from simple elements.

Russell’s senior thesis focused on the most important joint in these guadua structures, the fish-mouth connection. Lu Lu performed an in-depth parametric study on one of the hypar structures, allowing to improve the structural behavior of the roof. Lu Lu and Russell, traveled together to Colombia to visit the bamboo structures and optimize their analyses in collaboration with the Colombian team. Tim followed up on this visit, by providing further assistance in Cali on the seismic analysis of these grid shells. Overall, the Form-Finding Lab’s efforts will have an impact in Colombia, as the eventual design of the structures will be optimized using the input of the team. Construction is about to start in the upcoming months!

Russell Archer and Lu Lu during their visit in Colombia.

Author: Tim Michiels

Do utilitarian silos have any esthetic value?

4In ‘Vers une architecture’ Le Corbusier praises the aesthetics of silo buildings, tall machines composed of geometric shapes, designed and built by engineers for strictly utilitarian criteria. He refers to examples such as the silo Bunge y Born (Buenos Aires), shown in the book ‘Jahrbuch des Deutschen Werkbundes’, and claims:

“The engineer, inspired by the imperative of economy and guided by calculation, sets us in accordance with the laws of the universe. He achieves harmony.”

Malmo Cement Silo, captured from its base with a wide angle camera.

The 2D pictures and structural cross-sections of 3D Malmö cement silo (Sweden) in the catalogue ‘PuL Ingenieure 65A001 – 15A073’, issued at the 50th anniversary of  Stuttgart engineering design office Peter und Lochner Beratende Ingenieure, show the same simplicity and elegance Le Corbusier applauded. The photographs taken by the client IBAU  Hamburg, have captured the silo from its base with a very high camera angle. The images are cropped in such a way so that the sky, foreground and adjacent buildings disappear. The silo stands – like a piece of art in a museum – by itself; it does not relate to the surrounding site. The aesthetic character of the silo is shown to us by focusing solely on shape and external volume. The photographer has captured the silo lit at night so it appears even more dramatic and imposing.

Interior view of silo with open top section, light and shade articulate 3D form, Malmö, Sweden

In addition, light and texture, gives the Malmo silo additional “visual” weight. The light (or absence of it) plays an important part in articulating the nature of the three dimensional form and shade gives the appearance of solidity in the photograph of the interior.

The silo’s shape, shown in the cross-section as a radial assembly of forms, is quickly and easily visually read because it is made up of a familiar cylindrical and conic forms. The perception of these pure surfaces of revolution without the distraction of additional features and ornamentation, conveys visual strength – a desirable characteristic for a silo.

The Malmo’s shape, shown in cross-section as an assembly of cones and cylinders.

The Malmo cement silo photographs and cross-sections in the PUL Ingenieure Catalogue convey the beauty and drama to be designed and found in utilitarian structures, even when designed purely for functional and economic criteria.

All images credit: PUL Ingenieure Catalogue

Authors: Imgard Lochner-Aldinger, Sigrid Adriaenssens