Seismic performance of a joint with replaceable flange-opening beam segment

To realize the outward movement of plastic hinges under earthquake action and the rapid repair of the structure after earthquakes, a joint with replaceable flange-opening beam segment (JRFOBS) was proposed. The joint was designed based on the concepts of weakened section and replaceability. The joint was tested under low-cycle reciprocating loading to study the seismic performance, and the hysteresis curve, skeleton curve, ductility coefficient, energy dissipation capacity and stiffness degradation curve of the joint were obtained. With the help of finite element software, this joint was analyzed by variable parameters of opening diameter of different beam-column section sizes. The results show that the joint can make the plastic hinge of the beam end move outward to the opening weakening of the replaceable beam segment, and has good bearing capacity, ductility and post-earthquake repairability. With the increase of the diameter of the openings in the replaceable beam segment, the ductility, energy dissipation capacity and stiffness of the joint gradually decrease, but they can still meet the relevant requirements of seismic performance. Therefore, it is recommended that the opening diameter is 0.2–0.35 times the half width of the beam flange. After changing the beam-column section sizes, it is found that as long as the opening diameter is ensured to be between 0.2 and 0.35 times the half width of the beam flange, the joints with different beam-column section sizes can still satisfy the relevant requirements of seismic performance and the ultimate bearing capacity decreases by no more than 10 %.