ABSTRACT
Building form and material operate at dierent scales. Form is large and singular; material is small and comes in parts. While perhaps a gross characterization, this simple distinction is increasingly evident in the arena of parametric design whose explorations have focused on material assemblies dened by modulated elds. One presumption is that such relational models will aord greater connectivity among various aspects of the architectural work. However, with a bottom-up cellular or modular approach, how these systems aggregate or subdivide is oen conceived apart from overall building form. Predictable disjunctures oen play out between form and skin – either a form is wrapped by a skin that adjusts to t, as is the case both with conventional building materials and highly evolved parametric parts, or a skin makes an indeterminate form predicated on a modular system. It is not surprising therefore that nding eective translations between material and building scales is a growing architectural preoccupation. Intermittently throughout architectural history, whether weighted toward constructive necessity or design agenda, architects, engineers and builders have employed structure as the imperative that connects material with form. From traditional masonry construction to geodesic domes, this method of form making is largely dependent on geometry, the single most important factor in determining structural performance. Arches, vaults, domes, thin shells, tensile membranes, cable nets and the like intricately unite material with surface structure. e ultra-thin concrete hypar roofs of Felix Candela and catenary domes of Heinz Isler, Eladio Dieste’s sinuous brick walls, and Frei Otto’s wood lath grid-shells and steel cable nets are modern examples that celebrate the coupling of material behavior with structural surface geometry. ese architects employed extensive physical form-nding such as hanging chain models, plaster mesh casts, and cable nets loaded with weights carefully monitored by strain gauges to achieve optimized structural solutions. In contrast to such structurally pure models, the power of computation has opened possibilities for at once muddying and synthesizing geometry, structure and material performance. Where the earlier twentieth-century experiments employed a more or less uniform tectonic based on symmetrical structural diagrams, contemporary analysis and design techniques can eciently adapt a material system to address variable, localized, and non-symmetrical loading conditions. e seemingly ad hoc structural framework of CCTV designed by OMA and engineered by Arup serves as a good example of expressive structural modulation. e skin’s diagonal bracing tightens, changes size, and sometimes disappears altogether based on forces generated by the two-way building cantilever. Foster Partners and Buro Happold Los Angeles oer a more stealth approach in the design of the Smithsonian Institution courtyard roof enclosure. e roof canopy is similar to a minimal soap bubble surface geometry, but is far more shallow and non-uniform in its overall conguration. e resulting irregular stress pattern is addressed with a variant structural diagrid whose segments swell and shrink according to localized forces while the overall diamond pattern remains intact. Both these projects characterized by non-optimized structural form register the impacts of geometry on material behavior with a deviated tectonic system.
