Experimental investigation of the shear performance of bamboo scrimber beams reinforced with bamboo pins

Shear failure parallel to grain is a common failure mode for bamboo scrimber under flexural loading. To address this issue, the bamboo scrimber beams were reinforced with bamboo pins. Four-point bending tests were carried out on the bamboo scrimber beams, and the failure mechanism was analyzed. According to the test process of the specimens, the ultimate bearing capacity, load-deflection curves, load-strain relationship, strain distribution of the midspan section and interlayer slip law of the bamboo scrimber beams were obtained. The bamboo pins were found to be able to resist parallel-to-grain shear failure and effectively connect the upper and lower parts of the bamboo scrimber beams. The ultimate bearing capacity of the bamboo scrimber beams reinforced with bamboo pins was 1.1 to 1.6 times the ultimate bearing capacity of the control bamboo beams. In terms of deflection, when the shear-span ratio was less than 2.0, the increase in deflection of reinforced beams was more obvious than the increase in deflection of control bamboo beams. However, when the shear-span ratio is greater than 2.0, the increase in deflection is not obvious. Meanwhile, with the decrease in the bamboo pin spacing, the ultimate bearing capacity and stiffness of the reinforced beams also increased, and the slip between layers decreased. By analyzing the effects of the parallel-to-grain shear strength of bamboo scrimber and shear-span ratio on the shear stress of bamboo beams, the nonlinear relationship between the bamboo scrimber and shear-span ratio was given, and the formula for calculating the shear capacity of bamboo beams was obtained. The average error between the shear capacity calculated by this method and the experimental values is only 4.85%, indicating that this method can predict the shear capacity well.