梁构件之振动式快速损伤诊断技术

A Vibration Type Fast Damage Diagnosis Technique for Beam Structure

如何能够快速而又准确地进行桥梁损伤诊断,是目前桥梁养护管理单位所关心的问题,文章提出一种梁构件振动式快速损伤诊断技术,此方法以量测结构振动信号配合破坏力学及旋转弹簧的概念,进行损伤位置与劣化程度诊断之计算,并用SAP2000的数值模拟以及实际的铝梁敲击实验进行此损伤诊断方法的验证,实验中的自然频率是藉由频率域分解法(FDD)来计算,由互易定理量测到的力与加速度信号所得到的。最后更进一步地探讨以理论的模态振型及实际量测到的模态振型所计算的损伤位置与劣化程度的结果,以及损伤产生前后可能面临到的系统边界条件改变之问题。

In this paper, a fast damage diagnosis technique for beam structure is proposed. It can identify the location and severity of damage by the structural vibration signals, the stress intensity factor of fracture mechanics and rotational spring model. The capability and accuracy of this technique are verified by numerical simulations using SAP2000 code and muhiple-impact test on aluminum beam in the laboratory. The natural frequencies and mode shapes of each test beam were calculated from time history signals of impulse force and the acceleration signals obtained from the elastodynamic reciprocal theorem and the frequency domain decomposition （FDD） method. The difference of the damage analysis results using the theoretical modal shapes and experimentally calculated mode shapes is investigated. The effect of the boundary condition on the damage assessment technique is also addressed.