Experimental study of interfacial bonding performance between section steel and ultra-high performance concrete in PUES beam with the hollow section

To fully utilize the high strength and superior ductility of ultra-high performance concrete (UHPC) while saving construction costs, the precast inverted T-steel reinforced UHPC (PUES) beam with a hollow section was previously proposed. The objective of the study was to examine the interfacial bonding behaviors of UHPC and section steel, considering the effect of the hollow section. A push-out test program consisting of eleven specimens was carried out to explore interfacial bond behavior between section steel and UHPC. The crack development and interface bonding mechanism of specimens during the whole loading process were investigated using the load-slip curves ( P - S ) and the strain distribution at various positions of section steel. Variables such as embedded length, stirrup ratio, steel fibers volume fraction were analyzed based on the results of the push-out tests. The study established the characteristic bond strength equations between section steel and UHPC and the interfacial bond-slip constitutive model for section-reinforced UHPC beams with a hollow section, respectively. The proposed constitutive model accurately captures the bond stress-slip curve characteristics for the hollow section between section steel and UHPC, while predicting the characteristic strengths. This study provides a necessary foundation for the numerical modeling of PUES beams with hollow sections.