交变荷载下木构件增强端部钉节点抗剪性能

Screw shearing capacity of wood members' wnd reinforced using powdered carbon fibers in alternating loads

为克服木构件端部易开裂、力学性能差等不足,采用粉状碳纤维对木材端面进行增强处理,研究了木构件增强后端部钉节点在交变荷载下的受剪性能。结果表明:在单调荷载下,碳纤维增强后的水曲柳和落叶松木材端部钉节点抗剪力得到大幅改善,分别提高102.54%和78.23%;交变荷载能加速木构件端部钉节点损伤进程,交变荷载频率及荷载变化幅度是影响钉节点抗剪性能的主要因素;不同树种及不同端面钉节点剪切位移增量差异明显,剪切位移增量可用作评价交变荷载下钉节点抗剪性能优劣的参数;增强端面钉节点剪切破坏模式主要表现为钉孔边缘碳纤维涂层出现局部变形及钉剪切变形。增强后的水曲柳及落叶松木构件端面具有更优异的抗疲劳及蠕变性能,可应用于木结构工程。

In order to overcome the shortcomings of easy cracking and poor mechanical properties of wood member＇s end, the wood members＇ end was reinforced by using powdered carbon fibers. The screw joints shearing resistance capacity of wood members＇ reinforced end under alternating loads was studied. Results showed that under monotonic load, the screw joints shearing resistance capacity of Fraxinus mandshurica and Larix olgensis wood members＇ reinforcement end has been greatly improved, increased by 102.54% and 78.23% respectively. The alternating load could accelerate screw joints＇ damaging process. Alternating loading frequency and load amplitude were the main factors affecting the shearing resistance capacity of screw joints. The displacement increment which varied among different species and different ends was approved as a reliable evaluation parameter of screw joints shearing resistance capacity under alternating load. The shear failure mode of wood members＇ reinforced end was displayed by forms of local deformation of carbon fiber reinforcement layer aside screw and screw＇s shear deformation. Fraxinus mandshurica and Larix olgensis wood members＇ reinforcement end possessed more excellent anti fatigue and creep properties than unreinforced end, and could be applied to wood structure engineering.