Research On Seismic Behavior And Bending Capacity Of The Bottom Flange Bolted And Top Flange Welded Diaphragm-through Connection

According to the analysis and research of domestic and foreign scholars on the failure mode of CFST houses in earthquake,the piercing joints of the bolt-welded joints are not as reliable as the welding quality of the welding seam of the lower flange is complicated.Therefore,Under the flange weld damage is particularly serious.In order to improve this problem,the researchers put forward the full bolt diaphragms through the joints,but because of the high construction accuracy of the full bolts joints,it is not easy to carry out on the construction site.At present,there are three full-scale low-cycle reciprocating tests on the welds of the lower welds.However,the FEA results of the three joints can not be compared and analyzed because of the finite element analysis of welded joints.In this paper,we improve and perfect the experimental finite element analysis on the basis of three fullscale experiments on the welded joints of the welded joints,and compare the shape of the hysteresis curve,the trend of the skeleton curve,the strength degradation coefficient,the stiffness degradation coefficient,Ductility coefficient,energy dissipation coefficient and equivalent viscous damping coefficient,the seismic performance of the joints is compared.The calculated results and the experimental results show that the joints of webs with webs and webs are better than the ones with slotted joints.Based on the finite element analysis,the theoretical calculation and deduction of the bearing capacity of welded joints under the bolt are carried out.The ultimate bearing capacity of the joints is discussed and compared with the experimental data.The ultimate bearing capacity calculated by the formula Safety.The seismic performance of the welded joint on the lower bolt is parametrically analyzed.The number of bolts and the concrete-filled steel tubular column are selected as variables.The calculated data and the seismic performance of six joints are compared.The results show that when the bolt diameter is the same,The more the number of lower flange bolts,the better the node seismic capacity;the larger the concrete-filled steel tube column size,the better the node seismic performance.In the end,the static bending test and finite element analysis of welded joint,full bolt joint and welded joint on the lower bolt are carried out.The stress distribution and ultimate bearing capacity of the three kinds of joints are analyzed.Under the same steel specification,the stress distributions of the three kinds of joints are different,but the ultimate bending capacity is similar,and the welding joints on the lower bolts can be used instead of the full bolts or welded joints.