基于多尺度模型修正的结合梁斜拉桥损伤识别方法

Damage identification method of composite cable-stayed bridge based on multi-scale model updating

以灌河大桥为工程背景,提出了基于多尺度有限元模型修正的结合梁斜拉桥损伤识别方法.首先基于现场环境振动试验结果和两阶段响应面方法对初始多尺度模型进行修正,并将修正后模型定为原始未损伤状态;进而,利用多尺度模型修正方法对结构不同部位不同程度的损伤进行识别,并探讨了模态曲率损伤指标和单元模态应变能损伤指标对不同结构尺度损伤的敏感性.分析结果表明:在不考虑噪声干扰情况下,模态曲率和单元模态应变能指标对精细小尺度单元区域主梁微小(1%)损伤均较为敏感,可识别出结构的损伤位置,而对大尺度单元区域的损伤敏感性略低;在考虑噪声干扰情况下,精细小尺度单元区域比大尺度单元区域在损伤识别方面的抗噪性更好,且模态应变能损伤指标的抗噪性略优于模态曲率损伤指标.故而提出的多尺度建模及其损伤识别方法具有应用到实际工程中微损伤识别的潜力,并为大跨结构损伤预后奠定了基础.

The damage identification method based on a multi-scale finite element （FE）model up-dating for a composite cable-stayed bridge is presented with respect to the Guanhe Bridge.First, based on ambient vibration testing and the two-stage response surface method,the FE model upda-ting is conducted,and the updated model is chosen as the undamaged state.Secondly,a multi-scale FE model updating method is used to diagnose the structural damage at different positions and in dif-ferent degrees,and the sensitivity of damage indices including model curvature index （MCI）and modal strain energy index （MSEI）on different structure scale units is discussed.The analysis results show that without considering noise effects,the MCI and MSEI are sensitive to minimal damage （1%）of small scale units,and the locations of cracking damages can be identified,but they are in-sensitive to the big scale units;considering noise effects,the anti-noise ability of the small scale units is better than that of the big scale units in the damage identification,and the anti-noise ability of MSEI is superior to that of the MCI.The results support the idea that the proposed damage identi-fication method based on the multi-scale finite element model updating has great potential in the dam-age identification of practical engineering structures,and it lays a solid foundation for the damage prognosis （DP）of large span structures.