Analysis and experiment for the formation and ultimate load testing of a hypar space truss

This paper discusses the behavior of post-tensioned space trusses with the hypar (hyperbolic paraboloid) shape, and the ultimate load test that was performed on one such structure. The tested hypar space truss was post-tensioned in the bottom chords of one diagonal. In this paper, the essential characteristics of shape formation are discussed on the basis of a small-scale test model. Results of experimental testing and nonlinear finite element analysis indicate that a planar rectangular layout can be deformed into a pre-determined hypar shape using the shape formation method proposed in this paper. Also the feasibility of the proposed method for constructing a hypar space truss has been presented. It follows that a nonlinear finite element analysis can be used in accurately predicting the behavior of the space truss and the required post-tensioning force. Through ultimate load testing, it is shown that the hypar space truss has significant structural strength.