钢管桁架结构中T型相贯节点地震易损性分析

Seismic Fragility Analysis of Tubular T-Joint in Steel Tube Truss Structure

针对平面桁架结构中杆件承受轴力为主的特点,采用相贯节点腹杆与弦杆相贯面的局部变形作为衡量节点破坏程度的参数,建立了平面管桁结构中T型相贯节点发生轻微破坏、中等破坏、严重破坏的地震易损性指标.通过建立节点实体单元模型并对其滞回性能进行分析,建立了等效非线性分析模型,并与现有试验结果进行了对比分析,结果表明等效非线性分析模型能很好地模拟节点的局部变形,在保证了计算精度的同时,解决了地震易损性分析中计算时间过长的问题.选取单榀桁架结构关键点为非线性节点,使用Monte-Carlo法对桁架结构进行了地震易损性分析与评估,得到了易损性曲线,为此类结构抗震性能的评估提供1种新方法.

In order to acquire the behavior of members mainly bearing axial force in the truss structure,an index of circular tubular T-joint was proposed to analyze the seismic fragility,and the local deformation at the end of the brace relative to the chord axes was adopted as a parameter of damage state consisting of three levels,i.e.,minor,moderate,and severe damage.A detailed finite element model with dense meshing and a non-linear analytical model of the T-joint were built and validated.It is shown that the T-joint can be modeled with a non-linear spring.It is efficient for the new method to save more computing time than the traditional models while maintaining the accuracy in data simulation.An analytical model was built considering the non-linearity at a key joint to study the seismic fragility of the truss structure.The fragility curve of the truss structure was acquired through time-history analyses by the Monte-Carlo method.It is a new method for the seismic performance evaluation of truss structure with the seismic fragility data and curve.