Parabolic Framework


The Kilden Concert Hall may not appear to be a typical parabolic surface, but each of the wood strips on the underside of this cantilevered roof.  Each piece of wood starts at the same point on the roof and then connects to a point on a curve near the ground floor, also called a ruled surface.

The performing arts center presents a stunning experience for transitioning the audience between the riverside and a dramatic atmosphere of the three theaters. When looking at the seamless transition of the wood panels from inside to out at the window seen above, the glass extends beyond our site. In this detail the wood engulfs any suggestion of structure, yet the roof stays suspended in space as a surreal gesture.

 These magic moments in architecture show the rigor of the design process. I attempted to understand this connection and the process that made this detail work so seamlessly.  From studying ALA Architect’s sections and photos, I discovered the roof structure is a cantilever that suspends the ruled wood ceiling with an intricate framework of steel. This system is them masked by a perfectly smooth and seemingly parallel wood boards. But the simplistic look only occurs because of meticulous parametric modeling and a CNC router.

In my own study model I discovered the importance of the angular sides of each set of wood pieces that keep the boards parallel as the extremity of their curvature changes.  In this study I realized the glass is structurally supported by the 16″ vertical mullions, a system completely separate from the roof cantilevered wood slat ceiling.  The challenges of creating a curve from straight boards is apparent in the gaps between the straight slats in my model seen below. My physical investigations unveiled the true challenges of two structural systems meeting at such a clean point.  Several angles dictate the cuts of each individual wooden slat. As these elements twist more, their angles become more sever. Then at the window these elements are cut at their ends parallel to the pane of glass. To accommodate the changing angles of the wood slats over such a long distance, the roof seams to be divided into segments to simplify the production process. Sometimes to understand these systems it helps to look at a precedent. Felix Candela’s work (seen below) used wood boards (forming ruled surfaces) to make hyperbolic parabolic forms out of concrete structures. The interesting difference is that Candela’s work is structurally significant and allowed him to span at least 40 feet of space with only a few inches of  rebar and concrete.  In the ALA project, any structure is discretely hidden behind the wooden ceiling.  There is an inspiring aspect to each application. Each surface’s curvature is contradicting conventional applications of these materials. This nature, whether or not we recognize it, will fascinate us and encourage us to inquire further and better understand the structure that causes these phenomena.

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