Experimental study on seismic damage of joints with T-shaped CFST columns and steel beams

To investigate the seismic damage rule of T-shaped concrete-filled steel tubular (CFST) columns-steel beams joints under different lateral loadings, 11 specimens with the scale ratio of 1 / 2 were designed and fabricated. The design parameters of the tests were the loading mode (cyclic reversed loading, cyclic reversed and monotonic hybrid loading, cyclic reversed loading with constant amplitude, and monotonic repeated loading), depth to width ratio (2, 3), and axial compression ratio (0. 2, 0. 3 and 0. 4) . The failure pattern, load-displacement curves and hysteretic energy dissipation were analyzed. The results reveal that the failure pattern of the joint core area is mainly the shear failure and diagonal compression failure. The hysteretic curves of the joints are plump without a obvious pinch effect, and the joints have good energy dissipation capacity with the equivalent viscous damping coefficient of 0. 317 ~ 0. 396 at the failure point. The energy dissipation capacity of the joints decreases with the increased axial compression ratio. With the increase of hysteretic energy dissipation and deformation, the ductility of the joints decreases gradually. Under cyclic loading with constant amplitude, the larger the amplitude is, the faster the seismic damage of the joints develops, and the fewer loading cycles the joints experience when the specimens fail. Increasing the depth to width ratio can effectively improve the bearing capacity and ultimate deformation of the joints and delay the seismic damage development of the joints gradually. Based on the experimental results, considering the influence of plastic deformation, loading path and hysteretic energy dissipation on the joint seismic damage, a modified two-parameter seismic damage model was proposed and the damage indexes of the joints at the characteristic points were given. It reveals that the calculated results are in good agreement with the experimental results, and the seismic damage of the T-shaped CFST columns-steel beams joints can be accurately evaluated by the modified seismic damage model. © 2023 Science Press. All rights reserved.