层板销合木的界面滑移与木梁受弯性能

Evaluation of Interfacial Slip and Flexural Behavior of Dowel Laminated Timber Beams

层板销合木(简称销合木)是一种由规格材通过销组合而成的新型结构用木材,与胶合木相比具有加工快捷、成本低且更加绿色环保等优点。为研究销合木梁的弯曲性能,设计了8组木梁的四点弯试验,试验参数包括销的种类(木销和竹销)、销间距(70、100和140 mm)和层板的数量(3、4和6层)。此外,为揭示层积材界面销连接抗剪性能对销合木梁受弯性能的贡献,开展了木销和竹销连接销合木推出试验研究。研究结果表明:与木销连接相比,竹销连接的抗滑移刚度更高且延性更好;销合木梁的受弯性能介于无销接叠合木梁和胶合木梁之间,其组合效率为0.11~0.15;随层板数量的增加,梁截面的增高使销合木梁的抗弯性能显著上升;减小销间距对销合木梁的抗弯承载力与刚度均有一定的提升作用。采用欧洲规范5中的γ法预测销合木梁的抗弯刚度时结果偏大,因此认为对销合木梁的抗弯刚度进行计算时须对销连接的滑移刚度进行折减。

Dowel laminated timber(DLT)is a kind of novelty structural timber made of lumber connected by dowels.Compared with glulam,it has the advantages of fast processing,low cost,and more green environmental protection.To evaluate the bending performance of DLT beams,eight groups of DLT beams were tested under four-point loads.The testing parameters include the types of dowels(wood and bamboo dowels),dowel spacing(70,100 and 140 mm),and the number of laminates(3,4,and 6 layers).In addition,to reveal the contribution of the interfacial dowelled connection among lumbers to the bending performance of DLT beams,push-out tests were also conducted on the wood or bamboo dowelled connection of DLT.The test results indicate that the bamboo dowel connection show a higher slip stiffness and a better ductility compared with wood dowel connections,and the bending performance of DLT beams with a composite action range from 0.11 to 0.15 which is lower than that of glulam beams but higher than that of unconnected timber beams.The bending performance of DLT beams increases significantly when adding the number of the laminates,while reducing the dowel spacing could improve the bending capacity and stiffness of DLT beams.Due to the fact that the bending stiffness of the DLT beam would be overestimated by theγmethod provided in Eurocode 5,a recommended reduction factor was proposed for the connection stiffness when it was used to calculate the bending stiffness of the DLT beam,to facilitate engineering design.