Research and model test on fatigue performance of steel-concrete composite joint in space rigid frame

Based on the similarity principle of geometry, physics and boundary conditions, a 1:2 scale test model is designed to investigate the fatigue performance of steel-concrete joint section of the space rigid frame. Fatigue load is applied to the test model according to the design serviceability life, and the variations of stress and deformation of main members, weld and shear connectors with loading history are obtained. The results show that the stress of steel-concrete joint is low and the stress distribution has no remarkable variation during fatigue cyclic loading. The relative slippage between steel box and concrete is small. Moreover, there's no visible crack on the steel and concrete structure after fatigue test, and the results of ultrasonic inspection show that there's no defect found at the weld exceeding code specifications. The interfacial bond between steel and concrete on the top of composite joint is destroyed, but the maximum relative slippage is only 0.036 mm due to the effect of shear connectors. The steel-concrete composite joint of the space rigid frame has good fatigue performance. In the end, the reasonable design of steel-concrete composite joint is discussed in the view of fatigue property.