Research On Stress Concentration And Ultimate Strength Of The Cast Steel Joint At The Bottom Of The Bifurcated Column In The Center Of Exhibition And Sport In Nantong

With the advantages of lightness, beauty and lower steel consumption, Steel tubular structures have got a fast development and wide application in China. Cast-steel joints which applied to the civil engineering by the designers represent many advantages such as beauty, freely design and safety.As a large-scale project, there are many cast-steel joints in the center of Exhibition and Sport in Nantong. Especially at the bottom of the bifurcated column, the cast-steel joints have been designed. To assure the cast-steel joints working in gear, it is necessary to analysis the joint and to find and settle the problem in design. By the aid of finite element analysis software-ANSYS, the stress concentration and the ultimate strength of the cast-steel joint at the bottom of the bifurcated column have been analyzed and some helpful suggestions is presented.Firstly, the writer analyzes the state of the stress of the cast-steel joint at the bottom of the bifurcated column under four load cases. According to the stress of the measure points placed on the cast-steel joint it can be concluded that the stress concentration occurs on the cast-steel joint. And according to the theory of the stress concentration about the multi-tubular joint in some other articles, the part where the phenomenon of the stress concentration will occur is the area where the tubes connect with each other. Then it is proved that the filleting area and the inner plate stiffener is efficient to decrease the stress concentration.Secondly, by the aid of the software-ANSYS, comparison of the cast-steel joint at the bottom of the bifurcated column and the cast-steel joint without the filleting area in respects of the ultimate strength and the destroyed form is presented. Inelastic large stress finite element analysis of the cast-steel joint at the bottom of the bifurcated column under the change of various geometric parameters is developed too. The full loading-displacement path is traced, on which the ultimate strength of the joints are determined, some factors including grid precision, boundary condition and material properties are also considered. In the analysis, considering the advantages of 10-node solid element, the writer applies it to the cast-steel joints respectly to make the computed ultimate strength results closer to the real solution. Analysis proves that, if designed reasonably, the multi-tubular cast-steel joints only yield to axis force with one tube. The fracture forms of crushing and excessive deformation due to the pulling and pressing of the branch tube can be avoided, which can improve the safety of the structures.At last, the paper brings forward some initial researches on the rationality of the joints'construction from the view point of the production technics of cast-steel and gives some codes and suggestions to engineering design, which will be benefit to the designers.