Seismic behavior of CFRSTC composite frames considering slab effects

This paper reports on an experimental and numerical investigation conducted on the seismic behavior of concrete-filled rectangular steel tubular columns (CFRSTC) composite frames. The experimental study was conducted by subjecting two full-scale composite frames to simulated seismic loads. Both frames were composed of CFRSTC and steel beams. One specimen was placed on a reinforce concrete (RC) floor slab and the other was not. The purpose of the test was to investigate the elasto-plastic performance of the CFRSTC composite frame system and to examine the effects of composite action on the behavior of composite frames. The test results showed that the stiffness, strength and energy-dissipating capacity of the CFRSTC frame increased significantly with the presence of the floor slab. Compared with a bare steel beam, the composite beam experienced a decrease in the rotation capacity from 0.046 rad to 0.026 rad. The shear deformation of the panel zone grew because of the composite action, which delayed the fracture of the beam. Finite element (FE) models were established to simulate the tested frames. The results of the FE model fit well with that of the test model in terms of stiffness, strength, hysteretic behavior and component deformation.