Experimental Research And Automatic Analysis Of Welded Hollow Spherical Joint Under Complex Stress

The welded hollow spherical joint has become to a joint that got wide application in the reticulated structure because of its simple construct, convenient connection and regular shape. Recently, more and more super welded hollow spherical joints were used in the engineering in order to satisfy the need of big span of reticulated structures. However, data about mechanics and bearing-capacity of large welded hollow spherical joint is short of up to now. So it makes good sense to study the static performances of such joints and propose a method to conduct practical projects. In this paper, basing on the secondary stadium of Wuhan Sports Center, a representation large welded hollow spherical joint that under complex stress was studied and systematic analysis using theory and experiments.Firstly, basing on the F.E.M, considering the geometric nonlinearities and material nonlinearities, the welded hollow spherical joint was analysis by finite element analysis software ANSYS. The model based on Bilinear Isotropic Hardening elasto-plastic mechanical and the Von-Mises collapse criterion is established by using the element of shell143 in the ANSYS. The Newton-Raphson increment iterative method is adopted with accelerating convergence technique as line search, DOF predictor, and automatic time stepping.Secondly, strain detectors were layout basing on the results of F.E.M analysis, the experiments programs of the joints were designed and the full-scale experimental research on large welded hollow spherical joint was carried out in order to get the stress condition of the key parts in the joints and get the bearing-capacity of the joints. Through the comparison of the test results and the finite element results, the finite element calculation method used in this paper is proved accurate and viable.Finally, basing on the APDL language in the ANSYS, the computer program about welded hollow spherical joins was established through the secondary development, so it makes easy to input the numbers of the poles, the geometric parameter of the joints, the loads of the joints, and then the program can establish the models, loading, analyze and output the results by itself. Though the same methods the automatic analysis of different kinds of spherical joins can be realized, so a new method was provided to do the theory research of the spherical joins.