基于环境激励和子空间技术的自锚式悬索桥结构模态参数识别

Modal Parameters Identification of Self-anchored Suspension Bridges Based on Environmental Excitation and Sub-space Technology

结构模态参数的准确获取是自锚式悬索桥静力计算、抗风和抗震分析的重要基础。借助振动测试设备,在自锚式悬索桥加劲钢箱梁内记录了加劲梁多个测量点在环境激励下的振动响应时程,采用基于参考点的随机子空间技术开展了模态参数识别,获得了主跨350 m自锚式悬索桥的振动频率、振型和阻尼参数。试验结果与有限元分析对比表明,子空间识别技术能获得实际桥梁振动模态,而有限元分析存在明显不足,需要基于试验结果开展有限元模型修正。

Accurate identification of modal parameters is an important consideration on structural analysis,wind and earthquake response of self-anchored suspension bridges. By applying vibration test equipment inside a box girder of a self-anchored suspension bridge with a main span of 350 m,vibration time histories at various locations on the main girder are recorded under environmental excitation. Based on stochastic sub-space technology combined with a reference point,modal parameters of the self-anchored suspension bridge are presented and compared with the FEM results. It is found that the stochastic sub-space technology is capable of identification of modal parameter of real bridge in service,while FEM presents results which may not accurate and require model updating based on test results.