Building for the Future: Evaluating the Current Viability of Thin Shell Concrete Structures

Thin shell concrete structures are rarely built today. In their heyday from the 1950s to the 1970s, these structures provided efficient, economical shelter in many parts of the world under various loading conditions. Most of them are still standing in excellent condition and have required little maintenance. And in the hands of their most accomplished designers, such as Felix Candela, Pier Luigi Nervi and Heinz Isler, they possess an elegance and aesthetic adventurousness that marks them as works of structural art. Yet after the 1970s, this form was essentially abandoned as a medium for the structural designer. This project sought to address some of the reasons put forth as to why thin shell concrete structures are no longer designed or built. In so doing, the ultimate aim was to determine if thin shell concrete structures could re-enter the lexicon of today's engineers and again become a viable building style. Suggested reasons recently put forth to explain the dearth of contemporary concrete shell design include: that they are too complex to properly design and analyze; that they are too expensive to build; and that they are out of fashion with architects. The focus here is on the first issue, as it most pertains to structural engineers. To address that objection, I looked at thin shell concrete structures with the most current tools of design and analysis: finite element analysis and structural optimization algorithms. Some of the most sophisticated works of Felix Candela were used as the models for this study. Candela's hyperbolic paraboloid thin shell concrete structures represent a culmination of elegant aesthetics, efficient engineering, and economical construction. Finite element analysis and optimization of models of his works provide a great deal of insight into how a master builder designed his structures. Moreover, properly combined with an understanding of shell behavior, modern computational tools such as these could aid the contemporary designer in the design of thin shell concrete structures. This project also sought to propose some possible answers to the objection of cost. Candela's role as a designer-builder and his examples of extremely durable structures are proposed as a solution to the issue of cost. And while thin shell concrete structures may have fallen out of favor with designers, sustainability is currently an issue that is very much of interest in the design community. Here I propose that thin shell concrete structures are inherently sustainable, and deserve to be considered in attempting to find structural forms that fit this criterion.