Bond-slip Performance Between Welded H-shaped Steel and High-performance Steel Fiber-reinforced Concrete Based on Push-out Test

Based on the push-out test, the bond-slip behavior between welded H-shaped steel and high-performance steel fiber- reinforced concrete (HPSFRC) was investigated. Four influencing factors including concrete strength, concrete cover thickness, anchorage length and stirrup ratio were considered. Nine specimens were designed according to the orthogonal test design method. The specimens underwent two failure modes: splitting failure and push-out failure. The equivalent constraint coefficient re was proposed to determine the failure mode. The average bonding stress slip curves were plotted based on the measured load values and loading end slip data. The expression of multi-factor characteristic bonding strength was fitted. Verification analyses confirmed that the calculated values were in good agreement with the measured values. The ultimate bond strength increased with higher steel fiber volume percentage and concrete cover thickness, but decreased as the anchorage length was extended. Stirrups contributed to the enhancement of ultimate bonding strength, yet further increasing the stirrup ratio provided little additional improvement in this strength. Bond-slip constitutive relationships for splitting and push-out failure were developed, with the former adopting a three-stage model and the latter a four-stage model. The slope of the ascending curve of the push-out failure model was slightly larger than that of the splitting failure model, while the descending curve of the splitting failure model was more steeper than that of push-out failure model which showed obvious ductile failure characteristics.