Experimental study on the effect of column lateral friction torque on seismic performance of IMS structure middle joints

The design of prestressed friction joints of integral prestressed prefabricated frame structure system (IMS) has a direct impact on the internal force distribution and deformation of the structure. To study the seismic performance of the IMS structure under low cyclic reciprocating load, quasi-static tests were carried out, and two spatial two-way prestressed frame beam slab column middle joints were designed. The effects of friction torque produced by lateral prestress on the ultimate bearing capacity, stiffness degradation, energy dissipation performance, and self-centering of joints are compared and analyzed. The test results show that the specimen SCJ2 with large column lateral friction torque is better than the specimen SCJ1 in initial stiffness, bearing capacity, and energy dissipation, but the self-centering ability and damage control are slightly poor; The column lateral friction torque is about 31.64% of the cracking moment of joint SCJ1, 7.51% of the ultimate moment, 43.58% of the cracking moment of joint SCJ2, and 10.99% of the ultimate moment, the column lateral friction torque has a great impact on the crack resistance and bearing capacity of the joint, which can not be ignored in the design. At the same time, to verify the safety of the prestressed friction joint of the IMS system and evaluate the friction and shear performance of the joint after a large earthquake, the residual shear capacity of the joint is tested on the specimens after the quasi-static test. The test results show that IMS prestressed friction joints can still ensure good shear performance and have sufficient reserve of post-earthquake shear capacity.