Design and research of welded thin-wall box components for the National Stadium

摘要

Since width-thickness ratio of steel plates for welded thin-wall box component is quite large,local buckling on the compressed plates occurs easily. The conception of effective width can be used in calcu-lating the bearing capacity of thin-wall element. Referring to the design codes of steel structures in China and other countries, a new method to estimate effective width for welded thin-wall box section is presented in this paper based on the stress distribution of thin-wall box section. The favorable effect of low compres-sion stress on the effective width of plates and the shi ft of centroid between effective section and box section are taken into account. The bearing capacity formulas for thin-wall box sections under tension, compression,bi-axial bending, biaxial shear and torsion are provided. The FEM is used to analyze the warp stresses of the thin-wall box section under free torque and restraint torque conditions respectively. Various wall-thicknesses,including the flange thickness not equal to the web, and different height to width ratio of the sections are taken into consideration. The transverse stiffeners with square hole are introduced within box sections and the effect on the warping stresses is studied. Due to the complicated behavior of the twisted member and many influencing factors, and based on which the method of placing the transverse stiffeners is proposed to improve the stiffness of the members and stress distribution, effectively restrain the out-of-plane deformations of the arc walls.