One hundred sixty-two parallel bamboo strand lumber (PBSL) beams were tested for the bending properties under three-point bending with variable span. Two typical failure types were classified, type I was tension failure of the bamboo fiber located below the neutral axis at mid-span, while type II was shear failure which was mainly found in specimens with large depth-span ratio. The shear modulus \({\text{G}}_{{{\text{LR}}}}\) of PBSL was also calculated according to Timoshenko’s bending theory. To evaluate the shear modulus, 45° off-axis compression tests had been done. The results showed that the mean values of shear modulus for \({\text{G}}_{{{\text{LT}}}}\), \({\text{G}}_{{{\text{TR}}}}\), and \({\text{G}}_{{{\text{LR}}}}\) are 1254.5 MPa, 408.1 MPa, and 716.4 MPa, respectively. The bending test result was compared with the shear modulus measured by 45° off-axis compression test. It was found that the shear modulus measured by three-point bending test with variable span was significantly less than the shear modulus obtained by 45° off-axis compression test. The empirical equation of shear factor s corresponding to depth-span ratio h/l was proposed. The calculation results gained from the proposed formula are in good agreement with the 45° off-axis compression test results.

测试了 162 根平行竹材 (PBSL) 梁在变跨度三点弯曲下的弯曲性能。典型的破坏类型分为两种，Ⅰ类是竹纤维在中跨中性轴以下的拉伸破坏，Ⅱ类是剪切破坏，主要见于大深跨比试件。PBSL 的剪切模量\({\text{G}}}_{{\text{LR}}}}\)也根据 Timoshenko 弯曲理论计算。为了评估剪切模量，进行了 45° 离轴压缩测试。结果表明，\({\text{G}}}_{{{\text{LT}}}}\) , \({\text{G}}_{{\text {TR}}}}\)和\({\text{G}}}_{{{\text{LR}}}}\)分别为 1254.5 MPa、408.1 MPa 和 716.4 MPa。将弯曲试验结果与通过 45° 离轴压缩试验测量的剪切模量进行比较。发现变跨度三点弯曲试验测得的剪切模量明显小于45°离轴压缩试验测得的剪切模量。提出了深跨比h / l对应的剪切系数s的经验方程。从该公式得到的计算结果与 45° 离轴压缩试验结果非常吻合。