悬索桥损伤指标的适用性分析

依据精细的悬索桥有限元模型,分析比较了在无噪声情况下频变比指标、模态曲率差指标和静态应变差指标对悬索桥不同位置损伤的适用性.对主梁和吊索两种常见损伤类型的数值模拟发现,主梁损伤时,由于各阶指标之间信息的互补性,模态曲率差指标识别效果最好;吊索损伤则对结构整体频率的影响极其微小,无法用频变比指标来定位,此时静态应变差指标最为敏感.在试验的基础上,提出了根据损伤类型来综合运用频率变化比、主梁竖弯振型模态曲率变化以及静态应变差进行悬索桥的损伤定位的方法.

Applicability Analysis of the Damage Identification Indices of Suspension Bridges

Bases on the finite element model,this paper presents a comparative study of the applicability of the frequency changes ratio index,the modal curvature difference index and the static strain difference index for damage detection in suspension bridges in the absence of noise.From the two typical simulations of damage cases associated with longitudinal beams and cables,it is found that(1)modal curvature difference index is the best of the three indices because of the complementarity between each other in the beam damages;(2)when the damage occurs in the cable,the frequency is affected so little that it can't be identified by the frequency changes ratio index while the static strain difference index is the most sensitive index.On the basis of those results,a practical damage detection method for the suspension bridge is put forward combined with the frequency changes ratio index,modal curvature difference index,the vertical bending vibration mode and the static strain difference index according the damage cases.