Experimental study and theoretical analysis on interfacial mechanical behaviors of bamboo scrimber-UHPC/ECC composite members with innovative shear connectors

This study develops bamboo scrimber-concrete composite (BCC) members by integrating bamboo scrimber with concrete, aiming to enhance mechanical performance and promote environmental sustainability. A key focus is placed on shear connectors, which govern the interfacial shear behavior of BCC structures. To address this, three novel connector types, including C-channel steel, I-shaped steel, and T-shaped steel, are proposed and evaluated. To further improve structural performance, ultra-high performance concrete (UHPC) and engineered cementitious composite (ECC) are incorporated into the BCC systems. A series of push-out tests is conducted to examine the mechanical behavior and failure modes of the composite members. The study investigates how different connector geometries and concrete types influence interfacial performance. Results show that UHPC and ECC significantly enhance shear capacity and ductility while reducing the risk of cracking. Among the connectors, Ishaped steel achieves the highest shear capacity and stiffness but exhibits limited ductility. In contrast, T-shaped steel offers a favorable balance of strength and ductility, whereas the C-channel connector shows relatively poor mechanical performance. Building on these findings, finite element analysis is employed to reveal the load transfer mechanisms at the bamboo scrimber-concrete interface and to decompose the components of shear resistance. Parametric studies are then conducted to quantify the yield length of steel connectors, forming the basis for a predictive model of interfacial shear capacity. Additional analyses, factoring in variations in material properties, lead to practical recommendations for the selection of materials in BCC structural design.