STUDIES ON POSTTENSIONED AND SHAPED SPACE-TRUSS DOMES

This paper concerns studies on the shape formation of post-tensioned a nd shaped steel domes. The post-tensioned and shaped steel domes, asse mbled initially at ground level in an essentially flat condition, are shaped to a curved space form and erected into the final position by m eans of a posttensioning technique. Based on previous studies on this shape formation principle, three post-tensioned and shaped steel domes have been constructed. The results of the shape formation tests and f inite element analyses are reported in this paper. It is found that th e first two test domes did not furnish a part-spherical shape as predi cted by finite element analyses, because the movements of some mechani sms were not controlled sufficiently. With a revised post-tensioning m ethod, the third dome obtained the theoretical prediction. The test re sults of the three post-tensioned and shaped domes have shown that a n ecessary condition to form a desired space shape from a planar layout with low joint stiffnesses is that the movements of all the existing m echanisms must be effectively controlled as indicated by the finite el ement analysis. The extent of the maximum elastic deformation of a pos ttensioned and shaped steel structure is determined by the strength of the top chords and their joints. However, due to the semi-rigid chara cteristic of the top chord joints, the finite element analyses cannot give a close prediction for the maximum elastic deformations of the po st-tensioned and shaped steel domes. The results of the current studie s can be helpful for the design and construction of this type of struc ture.