胶合竹木梁抗弯性能试验研究

Experimental research on flexural behaviour of glued-laminated-timber-bamboo beams

以重组竹、胶合竹和云杉为层板材料,设计制作10组共计30根由六层层板胶合成的胶合竹木梁试件,并对其进行受弯性能试验,试验参数包括工程竹种类、层数、布置位置等;分析了各组试件的破坏模式、等效弹性模量、屈服荷载、承载力、变形能力及应变分布,通过不同胶合竹木梁组合方式的对比,提出最优组合方案;并根据组合梁的应变分布和简化本构关系,采用分层叠加法计算了各种层板组合方式胶合竹木梁的受弯承载力,同时对层板间胶层抗剪强度需求进行了分析。结果表明,在云杉胶合木梁的受拉一侧胶合工程竹板后,胶合竹木梁破坏时的变形能力较相同尺寸的纯云杉胶合木梁有明显提升,提升幅度为64.8%~123.9%;而在云杉胶合木梁的拉压区都胶合工程竹板后,承载能力和变形能力较相同尺寸的纯云杉胶合木梁都有显著提升,承载力提升幅度为63.9%~97.0%,破坏时的变形能力提升幅度为124.8%~167.5%;上部一层和下部两层木板替换成工程竹板后,承载力较纯云杉胶合木梁提高了82.3%,基本接近纯工程竹梁的力学性能,是较优的层板组合方案。

A total of ten groups of six-layer glued-laminated-timber-bamboo beams with 30 specimens were tested under flexural loads.The laminate materials include bamboo scrimber,laminated bamboo and spruce.The test parameters included the type of engineered bamboo,number and position of the bamboo laminates.The failure modes,equivalent elastic modulus,yield loads,loading capacities,deformation capacities and strain distribution were analyzed.Through the comparison of different laminates combination of engineering bamboo and timber,the optimal design method was proposed.According to the strain distribution of the laminated beams and the simplified stress-strain relationships,the flexural capacities were calculated with the method of layered superposition.The requirement on shear strength of the glued layer was also analyzed.The test results show that with the action of engineered bamboo in the outmost tensile layers,the deformation capacities of the composite beams are obviously improved by 64.8%-123.9%,compared with the spruce beams of the same size.In addition,the engineered bamboo in the outmost tensile and compression layers can enhance both the carrying capacities and deformation capacities: the load carrying capacities are improved by 63. 9%-97.0%,and the deformation capacities are improved by 124.8%-167.5%,compared with the spruce beams of the same size.Among the tested six-layer laminated beams,with the upper one layer and lower two layers replaced by engineered bamboo,the load carrying capacity is increased by 82.3%,which is basically close to the capacity of engineered members and was an optimized laminate combination.