互谱能量法在激励力未知条件下对结构的诊伤研究

众多结构损伤诊断的方法都是基于结构有限元模型，或者是基于结构激励力已知条件下进行的系统参数识别技术。然而，由于大型结构物激励力不易测试，这些方法应用于土木工程结构物存在着一定的局限性。因此。发展基于环境激励下抗噪声性能较好的结构损伤诊断方法对于土木工程结构物安全监测显得尤为重要。提出一个新的互谱能量法，实现了在环境激励力未知条件下对结构进行损伤诊断。互谱能量法诊断结构损伤无需已知结构本身的材料特性，无需系统参数识别，不是基于结构的有限元模型，仅基于结构动力可测试部分输出响应信号以及结构单元拓扑分布即可实现结构的损伤诊断。为了验证所提互谱能量法的有效性，数值模拟两跨连续梁结构，仅仅利用有限的动力测试信号，并且结构测试信号中加入了较大的噪声模拟实际的测试环境，研究结果表明互谱能量法能够有效地诊断出结构单一，多损伤位置的损伤，抗噪声能力较强。

Damage Detection Using Cross Spectral Energy Method with Unknown Excitation

Most existing health monitoring methodologies require direct measurement of input excitation for implementation of system identification,or base on a finite element model.However,in many cases,there is no easy wawy to measure these inputs,or alternatively,to externally excite these structures.Therefore,Structural health monitoring(SHM) methods based on ambient vibration have become important in civil engineering.Here,a new approach named Cross Spectral Energy Method(CSEM) is proposed to detect structural damage location under the unknown ambient excitation.The characteristic of this damage detection technology is directly based on the measured cross specturm density,which can avoid errors introduced by system identification methods.Furthermore,the cross spectral energy indicator is computed from measured response data without reference to a finite element model of the structure,only the structural topologic parameters enter the computation of the cross spectral energy field.In order to verify the efficacy of the proposed approach,simulation studies are applied to a 2-bay continue beam structure.Additionally,adding noise to the measured vibration response is performed to investigate the robustness of the methodology to damage identification.The numerical results demonstrate that the cross spectral energy indicator proposed is quite effective in the damage detection for single or multiple locations and is robust for noises.