基于模态柔度矩阵变化指标的结构损伤预警方法

Method of structural damage prewarning based on modal flexibility change index

根据结构损伤后其柔度增大的特征,在与实测自由度相应的柔度矩阵基础上,提出了基于模态柔度矩阵变化的损伤预警指标FI以及运用该指标对实际结构进行损伤预警或异常检测的步骤.损伤预警指标的敏感性分析包括不含噪声和含噪声情况.该指标的损伤报警阈值可依据结构在无损状态时由健康监测系统或定期检测所得到的实测模态数据以及结构有限元模型的模态分析结果计算得到.以润扬长江大桥斜拉桥为背景的数值模拟分析结果显示:无论有无噪声的影响,指标FI都随着斜拉桥拉索或主梁损伤程度的增加而增大,且大于相应的损伤报警阈值.在工程结构的使用过程中,可根据实测数据长期、连续地计算并观察指标FI的大小及其变化情况,在FI值超过报警阈值时给出报警信号.

A damage prewarning index FI is proposed based on the flexibility matrix corresponding to the measured DOF （ degree of freedom） and the characteristic that the structural flexibility increases with damage. The steps for damage prewarning or abnormality detection using the index are presented. The sensitivity of the damage prewarning index is analyzed for the case with and without noise. The damage-alarming threshold of the index can be obtained by measured modal data from periodical detection or structural health monitoring system as well as the results of FEM （ finite element method） modal analysis. The numerical analysis for the cable-stayed bridge of the Runyang Yangtse River Bridge indicates that the magnitude of index F1 increases with the increase of damage extent of cable or girder and is greater than the relevant damage-alarming threshold, no matter whether there is or is not noise. During the working procedure of engineering structures, the magnitude and variation of the index F1 can be calculated and observed continuously and perennially by measured data, and the alarm signal is given if the value of F1 exceeds the damage-alarming threshold.