Barrel-Vault Space Trusses Shaped by Posttensioning
This paper is primarily concerned with the formation of barrel-vault space trusses derived from a flat configuration by posttensioning. To obtain a fairly general picture of the shape-formation process by means of posttensioning, both gently and sharply curved barrel-vault models are studied. The structures are devised to be near mechanisms during the posttensioning operation. They are considered to be near mechanisms because only the flexural stiffness of the top chords provides any appreciable resistance to deformation apart from friction and self weight. Therefore, no appreciable axial force is induced in the members of the structures during the shape-formation process. The result of experimental and theoretical work on the shape formation of barrel-vault space trusses by means of posttensioning is presented here. The shape-formation process, referred to as self-erection, can lead to significant economies in the construction of large-span lightweight structures by eliminating or minimizing the need for scaffolding and heavy cranes.