Mechanical behavior of connections for glubam-concrete composite beams

Abstract

This paper reports testing results of various connections for composite beams made of concrete slab and glue-laminated bamboo (glubam) beam. Six types of composite connectors, commonly used in timber-concrete composite (TCC) beams, were tested under direct shear condition. The shear force-slip relationships were measured and all the relevant mechanical properties such as slip moduli and shear capacities were obtained. Compared with typical TCC beam connections, the Glubam-concrete composite (BCC) systems present several different characteristics. The shear failure along the notch, typical in TCC notched connectors was not observed for BCC system, however, the delamination cracking along the lamination layers occurred in some types of BCC connections. Based on the test results and analysis, six types of connectors can be classified into two categories, one with higher strength and stiffness but low ductility, and the other with lower strength and stiffness but higher ductility. A set of regression equation with a bilinear descent segment is also provided for simulating the shear-slip behaviors of each type connector. It is found that some of the connection systems including the notched connector, steel mesh connector, screw connector and pre-tightening notched connector, are more suitable and recommended for constructing BCC structures.