基于环境激励的连续刚构桥模态参数识别及有限元模型修正

一个合理准确的有限元模型是大型桥梁健康监测系统中损伤识别及安全评估、预警的前提。以一座三跨预应力混凝土连续刚构桥为例,根据设计资料,利用ANSYS建立其初始三维有限元模型,利用其健康监测系统采集得到的加速度时程数据,采用随机子空间法对实际结构的模态频率进行识别,依据识别结果,在参数灵敏度分析的基础上,根据最优化理论对该桥的有限元模型进行修正。研究结果表明,经修正后的有限元模型能真实准确地反映该桥梁结构的真实动力特性,可以作为健康监测中损伤识别、安全评估等研究工作的基准模型。

OPERATIONAL MODEL IDENTIFICATION AND FE MODEL UPDATING OF A CONTINUOUS RIGID FRAME BRIDGE BASED ON AMBIENT EXCITATION

The establishment of a reasonable and accurate finite element model is the precondition of safety assessment,early warning and damage identification in a large-scale bridge health monitoring system. On the basis of design information,a three-dimension FE model of a long-span prestressed concrete continuous rigid frame bridge is built with ANSYS. With the employment of the acceleration time histories from health monitoring system of this bridge,the operational modal frequency is identified by the SSI method. According to the results of identification,the FE model has been updated using optimization theory after the parameter sensitivity analysis. Results show that the finite element model updated can truly reflect the actual dynamic characteristics of the bridge structure,which can be used as the benchmark model of damage identification and security assessment in the health monitoring system.