Study On Seismic Performance Of Special-Shaped Concrete-Filled Steel Tubular Column To Steel Beam Joint

Four test specimens of special-shaped concrete-filled column to beam connection were conducted. Four specimens concluded two concrete-filled cross section column to steel beam connections with outer ring plate, one concrete-filled cross section column to steel beam connections with stiffener plate, one T-shaped concrete-filled column to steel beam connections with outer ring plate. The core area and the part of the column and beam between their points of inflection were concluded in the joint area. During the test, the axial pressure remained unchanged and low cyclic horizontal load was applied to the specimens. The displacement of the column, the strain of each part, and the shear deformation were measured in the test. The results show that the seismic index of concrete-filled cross section column to steel beam connections with outer ring plate is better than that of concrete-filled cross section column to steel beam connections with stiffener plate.Four specimens were simulated by using finite element software ABAQUS based on the dimensions of actual specimens. Plastic damaged model was used to simulate the constitutive relation of concrete. The geometric nonlinearity and material nonlinearity were considered in the simulation models. By contrast with the data of load-displacement plot and strain, it is found that the results of FE models are consistent with that of test models. Then parameter analysis was performed on flange depth, outer-ring-plate width, and the shape of vertical stiffened plate.Based on the FE data, the mechanical transmission mechanism of compression strut, steel web and reinforced bar is concluded. The joint is divided into concrete part and steel part, of which the bearing capacity is provided correspondingly. The composition of displacement of the frame is analyzed, considering the effects of.plastic hinge, the separation between tube and beam flange, the shear deformation of core area. The results of composition of different stiffness ratio vary greatly. Finally, improvement measure of the specimen and some design recommendation are put forward.