Influence of elevated temperature on the performance of pre-damaged grouted sleeve connections under tension and compression

This study investigates the performance of grouted sleeve connections (GSCs) under post-earthquake fire conditions. A total of 62 specimens were fabricated with variations in anchorage length (6 d , 7 d , 8 d ), pre-damage protocol (unidirectional and cyclic loading), and exposure temperature (20°C to 800°C). The response was evaluated based on residual deformation, hysteretic behavior, failure mode, strength, deformation capacity, and bond stress. Results indicate that GSCs become increasingly susceptible to rebar pull-out failure when subjected to shorter anchorage lengths, more severe pre-damage, and higher temperatures. Both yield strength and ultimate displacement decrease with increasing temperature. The ultimate strength of connections failing in pull-out is significantly lower than those failing by rebar fracture. Furthermore, while GSCs exhibiting rebar fracture satisfy standard performance evaluation criteria, those failing by pull-out do not. A bond stress coefficient k is proposed; for GSCs with an 8 d anchorage length, a value of k > 1.80 is recommended to prevent premature pull-out and ensure a ductile fracture failure mode. • Post-earthquake fire induces a failure mode transition in GSCs from ductile rebar fracture to brittle pull-out. • Anchorage length, high temperature, and pre-damage severity synergistically degrade bond performance. • A bond stress coefficient k > 1.80 is proposed as a threshold to prevent pull-out for 8 d anchorage. • GSCs failing by rebar fracture meet performance criteria, whereas those failing by pull-out do not.