多参考点脉冲锤击法识别桥梁模态柔度的实践

Practice of Bridge Modal Flexibility Identification Using Multiple-reference Impact Test

为了验证利用多参考点脉冲锤击法识别桥梁模态柔度的理论和实现方法,利用1根3个自由度悬臂梁结构验证了该理论和方法的可行性,并将该方法应用到实际桥梁的结构识别中,对2座旧桥分别进行了多参考点脉冲锤击法动力试验以及相应的静载试验。通过对钢-混凝土组合结构桥梁的模态试验,研究了多种参考点的选择方法,以比较参考点选择的不同对桥梁柔度计算结果的影响。研究结果表明:利用从多参考点脉冲锤击法动力实测数据的频响函数中直接获取的模态柔度,可估算结构在载荷下的位移,将其与结构静载试验获得的结构位移进行对比,结果可作为桥梁结构状况和性能评估的有效指标,并能成功实现对桥梁损伤位置的识别。

In order to apply the theory and implementation of using multiple-reference impact test （MRIT） to identify bridge modal flexibility, a 3 degree of freedom cantilever beam was utilized to verify the feasibility of this theory and approach. The approach was applied to structural identification of two real bridges, and the old bridges have been tested by using MRIT as well as the corresponding static load test. Through the modal test for steel-concrete composite bridge, the rational choices of different reference points in MRIT were researched to compare the effects of different reference points on results of bridge flexibility. The results show that the modal flexibility deflection extracted from FRF by using the dynamic experiment can be directly compared with the static test deflection. The results can be used as an effective index to evaluate bridge performance, and the method can successfully identify damage location on the bridge.