Analysis and Test for shaping Formation of Space Truss by Means of Cable-tensioning

For developing innovative construction techniques, extensive research has been carried out on the behavior characteristics for shaping formation of space structures by means of cable-tensioning method. This paper discusses the shaping formation of space structures by means of post-tensioning of the cable in bottom chords. It is a fast and economical construction method used in many types of space structures. Test models presented herein consist of uniform pyramids with multi-directional ball type joint, the space structure is shaped and erected into its final shape by cabletensioning in the bottom chords. The feasibility of the proposed post-tensioning technique and the reliability of the established geometric model were confirmed by finite element analysis and tests on a small-scale test model. Once the proposed posttensioning technique had been applied for shaping formation of space structure with multi-directional ball type joint, characteristics were determined from shaping test for practical design purposes. It proved to be an economic and reasonable method compared to conventional construction method including the heavy crane and scaffold. Introduction Space structure is relatively lightweight, easy to fabricate and transport, flexible in workability, and requires short period for construction. In general, though the major use of pre-stressing method is in concrete structure, recently various types of space trusses such a barrel vault, dome, hypar, arch shaped structures are being studied with model test and theoretical analysis for shape formation by post-tensioning (Clarke and Hancock 1995, Dehdashti, and Schmidt 1996, Kim 2000, 2001, Kim and Hao, 2002, Kim et al. 2001, Kim and Schmidt 2000, Kim et al. 2002, Kim, et al. 2004, Kim et al. 2006, Kim et al. 2005, Schmidt and Selby 1999, Schmidt and Selby 2001). Some engineers consider existing construction methods for space structures will remain the same as existing practice without recognizing the changes taking place in this practice. But it can be altered beneficially taking advantage of new approaches. For developing the innovative construction techniques, extensive research has been carried out on the behavior characteristic of shaping formation for space truss by means of post-tensioning method. Therefore, by means of post-tensioning, to improve the construction method and propose an alternative solution, shape formation test and theoretical analysis for the space structure was conducted with the test model that was consisted of ball type joint and steel pipe. When space structure is formed with post-tensioning, its behavior is known a nonlinear manner. Through model test and nonlinear finite element analysis, the behavior characteristic and the feasibility of formation for space structure with ball type joints were verified, and as a result, it can be used in the prediction of final shape for the space structure. Proc. ISCAS'07; Beale, R.G. (Ed.) ©2007, Oxford Brookes University