“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.”
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.”
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.
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.
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.
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 … Continue reading Design-and-build bamboo shells
In ‘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 … Continue reading Do utilitarian silos have any esthetic value?