Research On The Ductility Design Of Cable-supported Truss Structure

The cable-supported structure was a new type of tension spatial structure, which combined the advantages of both cable-stayed structure and cable-suspended structure. Cable in cable-supported structure went through the bottom of truss structure or grid structure and provided supporting for upper structures. Compared with cable-stayed structures, cable-supported structures were more effective in cable usage and had fewer restrictions on the angle between cable and beam, leading to better security and economics. It has been applied in engineering practices and scientific researching since its invention.In order to explore a way of ductile design of cable-supported structure that can be put into practice, the main contents of this paper included:(1) Static analyses of cable-supported tress structure were conducted. Models were established by FEA software and simulated under standard load, dead load and design load. During the static analyses, the appropriate initial cable forces and cable sections were chosen.(2) Bi-nonlinear stability analyses of cable-supported tress structure were conducted. Finite element models were established with the cable forces and cable sections that were chosen by the static analyses. Material nonlinear and geometry nonlinear were taken into consideration. According the analyses results, the final design cable force and cable section were determined.(3) During that two analysis steps above, the simulating results of two kinds of models, that one of its cable-supported nodes were simulated by degree of freedom coupling with spring element and the other were simulated by point-point contact element, were compared in order to prove practicability and validity of simulating the cable-supported with point-point contact element. The results indicated that those two kind of methods had approximate results and simulating the cable-supported nodes with point-point contact element had safer results.(4) Elastic-plastic time history analysis under rare earthquake of cable-supported tress structure were conducted. Finite elements models were established with the final design cable force and cable section and cable-supported nodes were simulated by point-point contact element. Seismic wave were chosen by the severest design ground motion theory with natural vibration period and site condition were taken into consideration. The part was conducted to check the design solution. (5) According to the analyses above, the practical ductile design method of cable-supported truss structures has been presented. First, the range of initial cable force was chosen according to the control conditions of structure displacement and stress requirements by the static FEA analyses, and the section of cable that fitted the cable force was also determined preliminarily. Second, the minimum cable section area was chosen when the structure bearing capacity coefficient larger was than2.0in bi-nonlinear stability FEA analyses. Finally, design result was verified in elastic-plastic time history analyses under rare earthquake.