位移放大型转动摩擦阻尼器增强榫卯节点抗震性能试验研究

古建木构中的榫卯节点属于典型的弱连接，地震作用时常常早于构件产生损坏，是预防性加固的关键节点。为提升榫卯节点的抗震性能，提出并设计了一种位移放大型转动摩擦阻尼器。通过对1组未设置阻尼器和3组设置阻尼器的足尺单向直榫节点进行了拟静力试验，得到并对比分析了加固和未加固节点的破坏状态、弯矩-转角关系、骨架曲线、强度退化曲线、刚度退化曲线以及耗能能力，分析了阻尼器的位移放大效应和拔榫抑制能力。结果表明:相对于未加固节点，设置摩擦型阻尼器节点的抗弯承载力最高提升了2.3倍；摩擦阻尼器具有显著的位移放大作用，其最大转动角度为榫卯节点转角的4.5倍；在不显著提升节点刚度的同时大幅度提高了榫卯节点的滞回耗能能力，且提高程度随螺栓预拉应变的增大而增大，最大可提升3.9倍；所研发阻尼器可有效抑制节点拔榫量，且抑制作用随螺栓预拉应变的增大而显著提高。研究结果可为古建木构的科学加固提供技术借鉴。

EXPERIMENTAL STUDY ON SEISMIC PERFORMANCE OF MORTISE-TENON JOINTS STRENGTHENED WITH DISPLACEMENT-AMPLIFIED ROTATIONAL FRICTION DAMPER

Mortise-tenon joints, the weakest links in ancient timber structures, are more vulnerable to disruption than members, and thus are crucial to preventive strengthening of the whole structure. In order to improve the seismic performance of mortise-tenon joints, a type of displacement amplification friction damper was designed. A full-scale one-way straight mortise-tenon joint without dampers and three counterparts with dampers were fabricated and subjected to pseudo-static testing. Failure modes, moment-rotation relationship, skeleton curves, strength degradation curves, stiffness degradation curves and energy dissipation capacity of both the strengthened and un-strengthened joints were obtained and analyzed. The displacement amplification effect and tenon-pulling inhibition capacity were analyzed. Results show that the bending capacity of the strengthened joints is 2.3 times larger than the unreinforced one. The maximum rotation angle of the damper is enlarged by 4.5 times compared with the mortise-tenon joint. The hysteretic energy dissipation capacity of the mortise-tenon joint is greatly improved without significantly increasing the stiffness, and the improvement degree gets larger with higher bolt pretension. With the increase of bolt pretension, the maximum energy dissipation can be increased by 3.9 times. The damper can effectively restrain the pulling out of tenon, and the inhibition effect is more significant with the increasing of bolt pretension strain. The research results can provide technical reference for the scientific strengthening of ancient timber structures.