基于模态参数的桥墩结构损伤识别数值研究

铁路简支梁桥桥墩横向振动时,可简化为墩顶具有集中质量的悬臂梁模型,地基约束用地基弹簧模拟。研究墩身的结构性损伤时,该模型与基底固结的悬臂梁模型原理相同。利用冲击振动试验法可以准确得到桥墩的一阶振型和一阶频率,利用这两个参数可以构造出一阶振型比、特征参数、一阶曲率模态差三个指标。以一混凝土悬臂梁为例,用一阶振型比、特征参数、一阶曲率模态差指标进行结构损伤识别的数值研究,总结了特征参数指标在结构损伤前后的变化规律。分析结果表明几个指标对损伤比较敏感。

Numerical Study on Structural Damage Detection of Pier Based on Modal Parameters

When the lateral vibration of a railway bridge pier is the cantilever beam with lumped mass on the top of the pier. The considered, the pier can be simplified as ground is modeled as springs. This simplified model has the same principles as the cantilever beam model with fixed root when the structural dam- age of the pier is studied. The first-order mode and the first eigenfrequency of the pier can be obtained easily and precisely by the impact vibration test method, from which three indexes such as the change ratio of the first mode shape, the characteristic parameters and the first curvature mode shape difference can be obtained. Then the three indexes are used as the measure for structural damage detection in a cantilever beam and their change laws before and after the damages are summarized. The analysis results indicate that these indexes are sensitive to the structural damage of the cantilever beam.