Bond behavior between section steel and concrete in partially encased composite structural members

In this paper, the bond behavior between the section steel and concrete in partially encased composite structural members (PEC) is investigated, and the concrete strength, anchorage length, and amount of expansion agent are considered. The results show that the ultimate bond stress of PEC increased as the concrete, bond length, and amount of expansion agent increased. Quantitative analysis of the bond stress composition between concrete and section steel, revealed that the length of the region where the chemical adhesive force existed was much larger than the length of the region where the friction force existed in the micro-slip stage. In addition, the bond stress distribution gradually transitioned from the H-shaped web to the flanges as the amount of expansion agent increased. Considering different influence factors, the characteristic bond strength formula was obtained through statistical regression. A prediction model of the bond-slip between the concrete and section steel in PEC specimens was established, and the optimized measurement method of the concrete strain value at the bonding interface was used to investigate the bond stress distribution of the H-shaped steel webs and flanges.