Flexural behavior of bamboo\u2013concrete composite beams with perforated steel plate connections

Abstract

A new type of bamboo–concrete composite structure using perforated steel plates as connectors was proposed. To study the composite effect of this new type of composite structure, the slip behavior of bamboo–concrete shear connectors was first studied through push-out tests. Subsequently, four-point bending tests of ten bamboo–concrete composite beams were carried out. The results show that the failure of bamboo–concrete shear connectors occurred between the perforated steel plate and the concrete, and there was no obvious damage between the perforated steel plate and the bamboo. The load carrying capacity of perforated steel plate connectors was relatively stable. The failure mode was moderate failure. Considering the three stages of the load–slip curve, an exponential function is proposed to describe the load–slip curve. The failure modes of composite beams can be summarized as two types. In the first type, the bamboo beam ruptures on the bottom and the concrete dose not suffer significant damage; in the second type, the top surface of the concrete first exhibits longitudinal cracks, and finally, the bamboo beam ruptures. Compared with bamboo beams, the ultimate load of composite beams increased by 1.2–1.5 times, and the sectional stiffness of composite beams increased by 2.9–4.2 times. The equivalent section stiffness was obtained after determining the connection coefficient, and the connection coefficient γb ranged between 0.50 and 0.80 and decreased as the center spacing of the perforated steel plate increased. The equivalent cross-section stiffness obtained by different load stages of the shear slip stiffness was calculated to predict the mid-span displacement. The calculation results show that the effect of slip stiffness on the equivalent stiffness of cross section is not sensitive, and a 35% increase in slip stiffness results in a maximum increase in equivalent section stiffness of only 6%.