为了研究不同形式直榫榫卯节点的抗震性能,参照《营造法式》及相关文献的构造要求,考虑不同榫头形式、不同模型比例、不同榫头伸出长度及不同材料对直榫榫卯节点抗震性能的影响,制作了14个T型直榫榫卯节点。通过直榫节点的低周反复加载试验,得到了不同形式直榫节点的破坏特征、弯矩-转角滞回曲线、骨架曲线、转动刚度及其退化规律和耗能等性能。试验结果表明:直榫节点的破坏形态主要是卯口、榫头的挤压变形和榫头部分拔出,梁、柱无明显破坏;直榫节点弯矩-转角滞回曲线形状呈反‘S’型,单向直榫节点的滞回环对称且饱满度较好,透榫节点、半榫节点的正向和反向滞回曲线呈现不对称性且饱满度较差,半榫节点尤为明显;单向直榫节点、透榫节点的承载力和转动刚度较大且相差不多,半榫节点较小;单向直榫节点的承载力大致与模型比例的平方成正比,但不符合模型相似关系;单向直榫节点增加榫头长度有助于提高其转动刚度,但当榫头长度大于柱径时,其提高幅度减小;透榫节点的耗能能力好于单向直榫节点和半榫节点;不同木材种类对直榫节点的承载力、转动刚度等性能有明显影响;直榫节点的转角可以达到1/8rad,表现出良好的变形能力。研究成果可为古建筑木结构的抗震分析提供依据。
In order to study seismic behavior of mortise-tenon joint models were made to meet the straight mortise-tenon joints with different forms, fourteen straight requirements of the Fabrication Methods of Song Dynasty and were tested by low-cyclic reversed loading. Some different conditions were taken into account to analyze their influence on the seismic behavior of the straight mortise-tenon joints, including joint types, model scales, the length of tenon and different materials. The failure characteristics, hysteretic and skeleton curves, degeneration of rigidity and something else were analyzed. The results indicates that the failure patterns are mainly squeeze deformation of mortise and tenon and partial evulsion of tenon. The shape of hysteretic loops of joints is anti "S" type, the hysteresis loop of one-way straight mortise-tenon joint is symmetrical and plump, which is not appropriate for through mortise tenon joint and half mortise-tenon joint. Compared with half mortise-tenon joint, the bearing capacity and rotational stiffness of one-way straight mortise-tenon joint and through mortise-tenon joint are greater and similar. The bearing capacity of one-way straight mortise-tenon joint is proportional to the square of the model scale. Increasing the length of tenon can improve the stiffness of the one-way straight mortise-tenon joint. The improvement gets smaller when the length of tenon is greaier than the column diameter. The energy dissipation capacity of through mortisetenon joint is the best in the three types of joints. Different kinds of wood has distinct effect on the seismic performance of joints. The relative angle of beam and column can be 1/8 rad, which exhibits good deformation behavior. The results can provide the basis for seismic analysis of the ancient timber structure.