Study On Seismic Performance Of Self-centering Circular Concrete-filled Steel Tubular Column To Steel Beam Connection With Web Friction Device

Self-centering structure system can reduce(or eliminate)the residual deformation of structure after the earthquake,so that the structure can be quickly restored to use after the earthquake.In order to reduce the residual deformation of concrete-filled steel tubular column to steel beam frame structure after earthquake,a kind of self-centering circular concrete-filled steel tubular column to steel beam connection with web friction device was proposed.This paper studied the mechanical characteristics and design method of the connection through theoretical analysis and quasi-static test.The main research work and results include:(1)The structural form and working mechanism of self-centering circular concretefilled steel tubular column to steel beam connection with web friction device were introduced in detail.The mechanical characteristics,deformation process and energy dissipation of the connection under cyclic loading were analyzed in theory.The analysis results show that the connection has good self-centering and energy dissipation ability,and it can reduce the deformation and damage of the main components.The structural form is feasible in theory.(2)In order to study the bending resistance capacity,the self-centering capacity,the energy dissipation capacity and the residual deformation of the connection,low cyclic loading test was conducted on three connection specimens.Moreover,the possible failure modes of the self-centering connection was analyzed.The experimental results show that the hysteresis curves of the three specimens showed a typical "double flag" shape,and which were consistent with the theoretical analysis results.The three specimens showed good self-centering and energy dissipation capacity,and its main components were keep elastic in the test,which indicated that the connection can reduce the damage of its main components.The structural form is feasible in practice engineering.(3)The effect of PT strand initial force and bolt initial force of web friction device on the mechanical performance of the connection were analyzed respectively by changing the test parameters of the connection specimen.The experimental results show that when the initial pretension of PT strand was increased,the bending resistance and self-centering ability of the connection were increased,the residual displacement of gap opening was reduced,and the initial pretension of PT strand had no significant influence on the energy dissipation ability and the stiffness after opening of the connection.The energy dissipation and the bending resistance capacity of the connection increased with the increasing of the pretension of high-strength bolts in the energy dissipation device.And the pretension of high-strength bolts in the energy dissipation device had no obvious influence on the self-centering capacity and stiffness after opening of the connection.(4)The seismic design objectives and the design criteria of main parameters for the connection were proposed,and the design flow of the connection was also introduced.The design calculation of the test specimen SCC3 was carried out to verify the effectiveness of the design method.