Experimental study of interfacial bonding performance between section steel and ultra high-performance concrete

The key to fully exploiting the benefits of section steel and ultra high-performance concrete (UHPC) is to improve their bonding. The primary goal of this study was to investigate the interfacial bonding performance between these two materials. Section steel reinforced ultra high-performance concrete (SSRUHPC) and section steel reinforced concrete (SSRC) specimens were subjected to push-out tests. Failure modes, load-slip (P-S) curves, and strain distributions were studied, and the experimental results showed that the P-S curves of all specimens have a similar trend: a no-slip stage followed by a slip stage, a failure stage, and a residual stage. By increasing the cover thickness and stirrup ratio and lowering the embedded length, the bond strength between the section steel and UHPC may markedly increase. The results of this study show that the bonding between section steel and UHPC is superior to that between section steel and ordinary concrete. Finally, after carefully considering the experimental results, regression formulae for the SSRUHPC bond strength were developed, and the computed results were found to be accurate. Unlike other bond strength formulae, the formulae in this study consider the influence of the stirrup ratio on the bond strength, and the R2 values range from 0.763 to 0.961.