用应变模态技术诊断梁结构的损伤

重点研究损伤对应变模态影响规律及其灵敏程度.根据计算结果,损伤处附近发生突变,损伤30%时突变区为梁长的12.5%.应变模态对非节点损伤非常敏感,应变模态也有明显改变,尤其是跨中损伤第1阶、四分之一跨损伤第3和第2阶.跨中损伤时,1阶应变模态除突变区外大多数应变几乎呈均匀下降趋势.四分之一跨损伤30%时,3阶应变模态第1峰值区及2阶模态第1、第2峰值区应变振型值下降至58.6%、71.9%及84.2%.所以,可利用应变模态的敏感性确定损伤位置和程度.

Application of strain mode in diagnosing damage to beam

Strain mode is applied to diagnosing the position and degree of structural damage, because of displacement modal parameter being insensitive to damage. The principles of damage effect on strain mode are studied.Based on the results of beam, it is concluded that strain modes are very sensitive to non-node damage. The abrupt change of strain is found around damage and the range is 12.5 percent of the beam if damage is 30 percent of its height. Furthermore, the change of strain mode is obvious, especially the first strain mode in middle span damage,the third and the second mode in quarter span damage. The value of the first strain mode shows equal downtrend in middle span damage. The first peak value of the third strain mode, the first and the second peak value of the second mode reduce to 58.6, 71.9 and 84.2 percent in quarter span damage of 30 percent.