Study on seismic performance and bearing capacity calculation of post-earthquake repairable high-strength steel joints with weakened-angle

Abstract

This paper combines common steel and high-strength steel to design a post-earthquake, repairable joint, considering post-earthquake function repairable and seismic performance comprehensively. To prevent early plastic deformation of the joint during the initial loading, slot holes are cut in the web and obround holes are cut in the flange of the angle. This is done to enhance the joint's seismic performance and its capacity for repair. Carrying out the proposed pseudo-static test and finite element parameter expansion analysis on the designed joints to compare and analyze the post-earthquake function repairable capacity of the joint. According to the different failure mechanisms, the calculation method of the bearing capacity and the design method of the joints are proposed. The weakened angle joints have low bearing capacity but the damage is completely concentrated in the damage element, and shows excellent ductility and seismic performance. The damage element was replaced when the story-drift was reached at 0.04 rad, and the peak bearing capacity before and after replacement errored by only 7.1 %. The maximum residual deformation of the joint is 0.48 %, which is lower than the threshold value for residual deformation of the post-earthquake function repairable structure, indicating excellent post-earthquake function repairable capacity. Based on the parameter and theoretical analysis, it is recommended that the thickness of damage element is not greater than the thickness of the beam, the length of the cantilever beam takes the value range of 0.18–0.25 times the total length of the beam, the bolts spacing of angle flange should be in the range of 30 times the thickness of the angle, and the reducing rate of the flange cover plate is about 0.7. According to the full-section plasticity theory, the peak bearing capacity can be calculated. The experimental and simulated values have an error within the range of 10 %.