实测模态下三跨整体桥精细化基准有限元模型

以一座新建的整体式桥台桥梁(简称整体桥)为工程背景，建立服务于健康监测的精细化基准动力有限元模型.将设计阶段基于梁格法建立的全桥三维模型与采用梁-壳单元的精细化模型作为初始有限元模型，把环境激励下获取的实测模态信息(自振频率与振型)作为参照，基于参数灵敏度分析修正了上述两种结构模型.结果表明：尽管两种模型修正后都可以获得与实测模态尤其是频率值较好的吻合度，但修正后的梁格模型的模型参数严重偏离其真实的物理意义，难以作为长期监测的基准模型；而修正后的精细化梁-壳单元模型的模型参数物理意义明确，可以作为计入环境因素影响(如温度、湿度等)的结构长期监测的基准模型.该研究还基于动力试验和模型分析结果讨论了整体桥特有的结构-土相互作用的问题.

Refined baseline finite element model of a three-span integral abutment bridge by using operational modal data

A refined baseline finite element model is established for long-term monitoring of a newly built integral abutment bridge (IAB) by using operational modal data. Both a design model based on the grillage method and a refined FE model using the beam and shell elements are taken as the initial models. The modal information (natural frequencies and mode shapes) identified under ambient excitation is considered as the reference data, while the sensitivity-based method is used for parametric updating. The main conclusions are as follow. Although both the simplified grillage model and the refined beam-shell model provide a good agreement with the experimental modal data, especially the eigenfrequencies, the parameters of the grillage model deviate from the physical meaningful values after the updating, which makes it impossible as the baseline model on the purpose of the long-term monitoring. In comparison, the physical meaning of the model parameters of the refined beam-shell model is retained, which allows the influence of the environmental effects, e.g., temperature and humidity, to be taken into account for the baseline model in long-term structural health monitoring. The relevant structure-soil dynamic interaction problem of the IAB as investigated by the numerical and experimental analysis is also discussed.