中文摘要：

在已建立的鹤洞大桥结构健康监测系统的基础上，同时采用 GPS 变形监测和加速度振动测试系统，在环境激励下对桥塔和桥主跨段进行位移和加速度响应的同步测试．采用基于总体平均经验模态分解法（EE-MD）的改进 HHT 方法，对 GPS 系统监测位移进行时频域联合分析，同时对于桥面加速度振动测试数据则采用常规的功率谱峰值法进行频域模态识别．通过2种不同信号采取2种不同模态参数识别方法，进行系统辨识结果对比分析，发现 GPS 监测位移可以较好地反映主整体结构的低阶振型响应，基于 EEMD 的改进 HHT 方法能较好地处理低频非平稳随机信号的干扰及模态混叠现象的发生；相对于常规的功率谱峰值法，本文所采用的改进 HHT 方法对模态参数辨识结果具有更强的优越性．同时通过2种不同测试信号对于部分阶次模态的系统参数识别结果，与有限元数值分析结果较为相近，验证了上述2种测试结果的正确和可靠性．GPS 变形监测系统与加速度动力测试子系统相结合，能较好地识别鹤洞大桥主模态参数，为大桥的安全有效运作提供坚实依据．

英文摘要：

Based on the established structural health monitoring system of He-dong Bridge,the simultaneous monitoring on the displacement and acceleration response at the main tower and bridge deck were conducted un-der ambient excitation for this bridge.The vibration displacements were measured by GPS deformation monito-ring subsystem while acceleration responses were monitored by accelerometers.The improved HHT technique, which was based on EEMD method,was utilized to conduct the time-frequency analysis on GPS monitoring dis-placement.Meanwhile the ordinary peak pick-up method,which is based on the normalized power spectral den-sity,was also adopted for modal parameter identification with measured acceleration signals.Compared results from two different identification methods showed the more advantage in the improved HHT method,as it could deal with the interference of non-stationary random signal in low frequency and reduce the incidence of the mo-dal mixture effectively.Meanwhile comparison with finite element numerical analyzed results implied that identi-fied modal parameters for this bridge from both HHT and peak pick-up methods are reliable.The combination of GPS deformation monitoring system and vibration acceleration test system could identify the modal parameter of He-dong Bridge effectively and could provide a solid basis for improving the bridge operation safely.