Posttensioned and Shaped Hypar Space Trusses

Publication Details

This article was originally published as: Li, H & Schmidt, LC, Posttensioned and Shaped Hypar Space Trusses, Journal of Structural Engineering, 1997, 123(2), 130-137. Copyright 1997 American Society of Civil Engineers. The journal homepage is available here.


This paper describes a kind of innovative posttensioned and shaped hypar space truss characterized by an economical fabrication and construction process. The hypar truss, assembled initially in a planar square layout on the ground, is posttensioned at the short bottom chords at one diagonal. As a result, the top chords become curved and thereby a nonzero Gaussian curvature surface of a hypar space truss is shaped. A distinguishing feature of posttensioned and shaped hypar trusses, compared with conventional metal trusses, is that the shape formation and erection is completed by a simple posttensioning process, rather than by the traditional techniques involving the use of cranes and scaffolding. The essential aspects of shape formation are discussed and a small-scale posttensioned and shaped hypar is formed in this paper. Results of experiment and nonlinear finite-element analysis indicate that, even within the yield limit of the members, a planar square layout can be deformed to a significant hypar shape by the proposed shape formation method. Potentially, this procedure can offer economies over traditional construction methods.

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