RESEARCH DESIGN OF TWISTED BOX-SECTIONS OF PRIMARYSTRUCTURES FOR NATIONAL STADIUM BEINJING

摘要

According to the configuration principle for the roof structure of the National Stadium, the axes of the twistedrnbox-sections are kept in the same plane, and can be deemed as being composed of a series of arc curves inrndifferent curvature radiuses. Due to the complicated mechanism of force transfer for twisted box-sections andrnnumerous influencing factors, the method of placing the transverse stiffeners is proposed through a profusion ofrncalculations, analysis, tests, researches and discussions on the fabrication process in the design. By settingrnstiffeners inside the twisted box-sections, we can improve the overall stiffness, stress distribution and localrndeformation of twisted box-sections, effectively restrain the out-of-plane deformations of the arc flange, andrnenhance the integrity and stiffness of the members. Twisted box-sections show obvious nonlinear characteristics.rnThe effect of geometrical nonlinearity should be taken into account in calculations and analysis. By adjusting thernthickness of the plates and intervals of the stiffeners, we aim to bring the strength and stiffness of the solidrnelement model in compliance with that of the beam element model; the factors such as space for weldingrnoperation and conservation of materials are taken into consideration in determining the shape of stiffeners. Thernbearing capacity and stiffness of the members are affected by wall thickness of the members and spacing ofrnstiffeners. One-direction tensile test results of the twisted box-sections and the test results of the local structurernon the top of the trussed columns accord with the results of finite element analysis well.