Dynamic And Static-based Finite Element Model Updating Of Bridge Structures

In essence, finite element (FE) model updating is the problem of optimization. The purpose of model updating is to identify and correct uncertain parameters of FE model that leads to the better predictions of structural real dynamic and static behavior. It can be used in structural health monitoring, analysis of dynamic response and damage identification et.al. The study of FE model updating has huge impact on theoretical analysis and great value on practical application. This paper focus on the objective function of optimization and FE model updating. A kind of new objective function of optimization, which combined dynamic and static characters from ambient vibration testing and static testing, was proposed and used to update the real bridge FE models. The main works included as follows: 1. The development of FE model updating techniques, the related aspects and the main problems unsolved at present were briefly reviewed; 2. The effects of the different objective functions based on dynamic behavior, such as frequency, model shape and modal flexibility, and based on the static displacement , were compared using a simulated simple support beam FE model updating. A kind of new objective function of optimization, which combined dynamic and static characters from ambient vibration testing and static testing was proposed. 3. Based on the dynamic testing of a simple support prestressed concrete beam, the dynamic behavior of the prestressed concrete beam under different prestressing value was analyzed; 4. The ambient vibration testing of a prestressed concrete continuous bridge with 8-spans was conducted. After that, the objective function combined frequency, model shape and modal flexibility was used to update the bridge FE model. 5. On the basis of ambient vibration testing and static testing, the objective function combined static and dynamic characters was used in FE model updating of a rigid-frame arch bridge after strengthening and maintenance. Some conclusions were extracted from the research and listed as follows: 1. The objective function combined frequency, model shape and modal flexibility was better in FE model updating and parameter identification than the other objective functions in dynamics, such as frequency, model shape and modal flexibility. A kind of new objective function of optimization, which combined modal flexibility and static displacement was proposed and confirmed to be the best. 2. The effect of prestressing on the prestressed concrete beam in dynamics is very small, and the prestressing parameter can be neglected in updating parameter selection during the FE model updating. 3. The objective function combined frequency, model shape and modal flexibility can be used to FE model updating of a prestressed concrete continuous bridge with 8 spans. The dynamic characters from FE model after updating agreed well with those from dynamic testing. 4. The objective function combined static displacement and dynamic modal flexibility can be used to FE model updating of the strengthened rigid-frame arch bridge. After updating, the dynamic and static characters from FE model agreed well with those from dynamic and static testing.