残损古建筑木结构单向直榫榫卯节点抗震性能试验研究

现存古建筑木结构均有不同程度的残损，而榫卯节点的残损对整体结构的安全性影响最大。为了研究不同残损类型、不同残损程度对单向直榫榫卯节点抗震性能的影响，制作了7个缩尺比例为1∶4.8的单向直榫榫卯节点模型，包括1个完好节点模型、3个人工模拟榫头真菌腐朽的残损节点模型和3个人工模拟榫头虫蛀的残损节点模型。榫头真菌腐朽和榫头虫蛀分别采用在榫头表面钻孔和在榫头钻通孔的方法来模拟。通过低周反复加载试验对单向直榫榫卯节点的破坏特征、弯矩-转角滞回曲线、骨架曲线、刚度退化规律和耗能性能等进行了研究。试验结果表明：单向直榫榫卯节点的破坏形态主要为榫头部分拔出、榫卯接触处挤压变形，柱和枋基本完好；所有节点的弯矩-转角滞回环形状呈反S形，且残损程度越大，滞回环捏拢效应越明显；残损节点的转动弯矩、刚度和耗能能力明显低于完好节点，且随着残损程度增加逐渐降低；相同残损程度的人工模拟真菌腐朽节点的弯矩和刚度大于人工模拟虫蛀节点，但耗能能力低于人工模拟虫蛀节点。

Experimental study on seismic behavior of damaged straight mortise-tenon joints of ancient timber buildings

The existing ancient timber structures all have damage with different degrees. The damage of mortise-tenon joints has the biggest effect on the safety of the whole structure. In order to study the influence of damage with different types and degrees on the seismic performance of one-way straight tenon mortise-tenon joints, seven one-way straight tenon mortise-tenon joints models with a 1∶4.8 scale made following requirements of the Fabrication Methods of Song Dynasty were tested by low-cycle reversed loading, including one intact joint, three artificially degraded joints with certain depth holes on the tenon to simulate fungi damage, three artificially degraded joints with through holes on the tenon to simulate termites damage. The behaviors of joints such as the failure characteristics, hysteretic loops and skeleton curve, degradation of rigidity and energy dissipation capacity were studied through low-cycle reversed loading experiment. The results indicate that the destructions occur at the mortise-tenon joints rather than in the beams and columns. The shape of hysteretic loops of all joints is S shaped and the gathering effect gets more obvious with the increase of damage degree. The rotation capacity, stiffness and energy dissipation capacity of the damaged joints are significantly below the intact one and reduce gradually as the damage degree increases. Under the same degree of damage, the final rotation capacity and stiffness of man-made fungi damage joints is bigger than that of the man-made termites damaged joints, but its energy dissipation capacity is lower than the man-made termites damaged joints.