木结构节点摩擦耗能及抗震研究

Research on friction energy dissipation and seismic performance of the joints of timber structures

对木结构节点建立了等效摩擦阻尼系统,依据能量等效原理将榫卯节点干摩擦耗散的能量等效为阻尼力做功,推导了节点关于干摩擦耗能的等效阻尼系数,以应用比较广泛的燕尾榫为例,通过有限元模拟得到了等效阻尼系数的大小。通过建立木框架结构,并在榫卯节点处引入MATRIX27单元模拟榫卯之间的干摩擦阻尼,选取兰州波和El Centro波,分别在结构考虑摩擦阻尼和不考虑摩擦阻尼的情况下进行了罕遇地震作用下的时程对比分析,引入无量纲的减震系数β来表示减震效果,得到榫卯节点在考虑摩擦阻尼的情况下,其节点位移和相对位移将会减小,而且荷载越大,减震效果越明显,说明榫卯节点的摩擦滑移在地震作用下具有较好的减震作用。

Based on the principle of energy equivalence, this paper establishes an equivalent damping system for the joints of timber structures and holds that the energy dissipation of dry friction in mortise-tenon joints is equivalent to working of damping force, therefore the equivalent damping coefficient about energy dissipation of dry friction was derived. Taking widely-used dovetail joints as example, the coefficient of equivalent damping can be determined by finite-element simulations. By establishment of timber structures and introduction of MATRIX 27 element to simulate dry friction damping on mortise-tenon joints, this paper selects Lanzhou waves and El Centro waves, whether having the friction damping or not, to make a time-history comparison analysis under the rare earthquakes. The dimensionless seismic reduction factor fl was introduced to represent the damping effect. The result shows that the displacement and relative displacement of mortise-tenon joints, under the consideration of friction damping will decrease, meanwhile, the damping effect increases with increase of seismic load, namely the friction sliding of mortise-tenon joints has better seismic reduction effect under earthquake.