BARREL-VAULT SPACE-TRUSSES SHAPED BY POSTTENSIONING

This paper is primarily concerned with the formation of barrel-vault s pace trusses derived from a flat configuration by posttensioning. To o btain 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 mechanism s because only the flexural stiffness of the top chords provides any a ppreciable resistance to deformation apart from friction and self weig ht. Therefore, no appreciable axial force is induced in the members of the structures during the shape-formation process. The result of expe rimental and theoretical work on the shape formation of barrel-vault s pace trusses by means of posttensioning is presented here. The shape-f ormation process, referred to as self-erection, can lead to significan t economies in the construction of large-span lightweight structures b y eliminating or minimizing the need for scaffolding and heavy cranes.