考虑局压效应的榫卯节点力学性能研究

木结构榫卯节点在受力过程中处于局部受压状态，通过木材横纹、顺纹方向的中部局压、端部局压、全截面受压性能的试验研究，得到了相应的材性参数；设计了钢榫头-木卯口、木榫头-钢卯口、木榫头-木卯口三组不同形式的分离式直榫节点试件，通过单调加载试验，对局部受压区域的应变分布特征进行了研究；基于试验研究得出的榫卯节点受力机理，建立了考虑局压效应的直榫节点力学模型。研究结果表明：木材横纹局压的抗压强度和弹性模量均高于全截面受压，顺纹局压与全截面受压的材性参数基本一致；榫卯节点受力区域的榫头应变远大于卯口应变，榫卯节点的受力挤压变形主要集中在榫头，而卯口变形可忽略；考虑局压效应的榫卯节点力学模型计算结果比未考虑局压效应所得的结果更符合试验结果。

Mechnanical properties of mortise-tenon joints considering local compression effect

The mortise-tenon joint is usually in a local compression state. In this paper, the compressive behavior of three kinds of stress regions, including the middle local compression, the end local compression and the full section compression, were studied along two grain directions of the wood, respectively. The corresponding wood properties were obtained. To study the whole process of strain evolution of mortise-tenon joints under local compression, three different forms of separated one-way straight mortise-tenon joints, including rigid mortise-wood tenon, wood mortise-rigid tenon, wood mortise-wood tenon, were tested under monotonic loading. On the basis of test results, the analytical model of one-way straight mortise-tenon joint considering the local compression effects was established. The results indicate that the compressive strength of the local section perpendicular to the grain of wood is higher than that of the whole section. The elastic modulus of wood in compression perpendicular to the grain is ten times of that of wood in compression parallel to the grain. Meanwhile, the strain generated in the tenon is much larger than that in the mortise. The deformation of the joint is mainly caused by the tenon, hence, the deformation of the mortise could be ignored. Furthermore, the calculated initial stiffness is much more likely to agree with test results with the consideration of the local compression effects.