Mechanical Performance Of Multiplanar Space Joint Of Substation Frame

In the design of substation and other steel structures,steel joints play an important role in connecting the pipes of the structures to guarantee their full function,which is the top priority in the work of designers.As the application of steel tubular joint is earlier and wider,its mechanical properties have been relatively well studied and the corresponding mechanical theory formulas have been obtained for the designers.Because of the advantages of convenient installation,simple manufacturing process,convenient transportation and so on,the tube-gusset joint has been widely used in engineering in recent years.There are few studies on its mechanical properties,and there is still a lack of domestic and international standards.It is of great significance in engineering application and theoretical analysis to study the steel joints with the characteristics of the tubular joint and the tube-gusset joint.Based on the background of 220 kV sail united framework substation engineering,a static loading test and nonlinear finite element analysis of the space joint of the full-scale model in the framework were carried out in the paper.Multiplanar space joint studied in this paper is provided with the characteristics of the tubular joint and the tube-gusset joint at the same time.In the full-scale model test,the loading scheme,the arrangement plan of strain gauges and the test plan were introduced and the test data were analyzed.According to 5 kinds of load conditions,the mechanical properties of the joint under 1.5 times the design load in each working condition were studied.The stress distribution and development of the joint in each loading stage were known and stress development curves of the observation points under 5 working conditions were obtained.The test results showed that the stress of each observation point of the joint didn’t exceed the yield strength of the material at the end of the loading and the joint had no deformation.On the basis of the test,considering the material nonlinearity and geometric nonlinearity,the finite element model of the joint was established and the finite element analysis of the joint was carried out according to the test loading system.For 5 working conditions,the stress development curve of each observation point,the load-displacement curve,the failure mode and the ultimate bearing capacity of the joint were obtained.The results showed that the experimental results were in good agreement with the finite element results and the ultimate bearing capacity of the joint under each working conditions was large.The joint was designed safely and reasonably,thus ensuring the safety of the substation project.