PLAN 64: Article
New Design Tool May Reveal Ancient Secrets

Method Can Model a 3-D Structure in a Matter of Minutes

A team of MIT architects, engineers and computer scientists has developed a new computer tool for modeling three-dimensional structures that could be used to unlock the structural secrets of ancient cathedrals.

The method, known as particle-spring systems, was originally developed for creating computer graphics such as character animation and the simulation of cloth – producing, for instance, the clothes worn by Yoda in Revenge of the Sith. But now, the MIT team – led by John Ochsendorf, assistant professor in building technology – proposes to use the technique to model the gravitational load on a given structural shape in order to find its most efficient form.

Used for this purpose, the method shows in three dimensions the lines and points of pressure in a structure’s building blocks, illustrating how each block reacts in relation to the others. The designer can change the form of a proposed structure and the forces acting on it even while the program is running, optimizing a three-dimensional model in a matter of minutes.

In a similar way the program could shed light on how Gothic cathedrals were built. By illustrating the lines of force that transfer the weight of the stones to the ground, the software could demonstrate that certain sequences of construction were impossible of standing safely, which would give new insights into the long-standing mysteries of their construction process. It could also be useful in old buildings that are showing signs of wear, where cracks can be identified as either harmless or potentially fatal to the structural integrity of the building.

The program can also be used for modeling structural elements such as trusses, slabs and beams, and holds promise for the invention of new building shapes which can carry loads more effectively and with less material. If it had been available in 1955, for instance, it could have reduced by half the amount of concrete used in the roof of MIT's Kresge Auditorium, a 1/8-of-a-sphere designed by Eero Saarinen.

Historically, creating new structural forms like Kresge’s dome was accomplished by painstaking physical means. Spanish architect Antoni Gaudi devoted ten years of his life to a ‘hanging chain’ model made of weights on strings that would serve as an upside down version of the arched forms he sought. MIT's new virtual method is just as straightforward as Gaudi's method but uses time, materials and money more efficiently.

Ochsendorf, a structural engineer with research interests including archaeology, the history of construction and sustainable design, co-authored a paper detailing the method with computation student Axel Kilian (PhD 2006). To fool around with the software online, go here. For more information, contact Kilian at akilian@mit.edu.

PLAN 64

June 2006