中文摘要：

应用有限元法将连续桥梁结构离散为两跨弱耦合欧拉-伯努利梁模型,研究了该弱耦合梁系统由于局部损伤而引起的振动模态局部化现象.利用Newmark直接积分法求出在移动车载作用下桥梁的动态响应,并进一步推导出动态响应桥梁对物理参数（如杨氏模量）的时域灵敏度.在反问题中利用基于响应灵敏度的有限元模型修正法识别出桥梁的局部损伤,并讨论了人工测量噪声对损伤识别结果的影响.算例表明该方法能够快速有效地检测具有相重频率的弱耦合系统的局部损伤,并具有精度高、对测量噪声不敏感等特点.

英文摘要：

In this paper, a multi-span bridge is discretized into a weakly coupled continuous Euler-Bernoulli beam system using the finite element method. The mode localization phenomenon due to local damages is studied for the system. Newmark integration method is used to calculate the dynamic response of the system under moving forces. The dynamic response sensitivity with respect to the physical parameter （i.e. elemental Young＇s modulus） is then obtained. In the inverse analysis, the local damages in the system are identified by dynamic response sensitivity-based finite element model updating method. It is found that the local damage（s） can be identified successfully by only a few acceleration measurements. The effect of artificial measurement noise on the identified results is also discussed. Numerical simulation shows that the proposed method can be used to identify the local damages in weakly coupled beam systems with repeated natural frequencies with very good accuracy, and it is insensitive to the measurement noise.