Bamboo Pavilion

Gradient Decent Optimization for Reciprocal Frame Structure

Year

2018

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My Role

Design Intern @Shigeru Ban Architects

Computational Design, Optimization Workflow, Physical Mockup

A reciprocal frame holds itself up through mutual rotation — each member leans on its neighbours, with no fasteners at the joints. The geometry is elegant but fragile: it only resolves when every member sits at precisely the right angle to the next, which makes scaling it onto a curved surface a quietly difficult problem.

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For Shigeru Ban Architects, this pavilion mapped a reciprocal frame onto a sphere under an uncompromising constructability brief: every bamboo member had to share the same length and the same thickness, so the structure could be cut, bundled, and assembled on site by students from Keio and Tongji without specialised tooling. That single constraint — fixed length, fixed thickness — skews the underlying quad-mesh mapping as it wraps the curvature.

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My contribution was a dynamic-relaxation algorithm that iteratively settles the frame under its own constraints, converging on a per-joint engagement length that responds to the local curvature of the sphere. Tight curvature pulls members deeper into one another; flatter regions let them sit lighter. The output is not a single optimised mesh but a field of joint-by-joint engagement values that the fabrication team could read off directly.

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Project team: Harano Yasunori (SBA), Jun Fujisaki (SBA), Anthony Chu (SBA). Constructed by Ban Laboratory, Keio University, with Tongji University.