Finite Element Model Updating for Improved Box Girder Bridges with Corrugated Steel Webs Using the Response Surface Method and Fmincon Algorithm

We propose a practical and fast finite element (FE) model updating method in which the response surface method and fmincon algorithm (FA) are used to modify the FE model of a new, improved box girder bridge with corrugated steel webs. Two three-dimensional FE bridge design models were compared to develop a reasonable initial FE model for updating this bridge. The response surface method (RSM) was used in our method for the optimal experimental design of the updated parameters, which were used as the basis of the numerical analyses performed to obtain the explicit relationships between the structural responses from the FE results and the parameters themselves. A comparison of the two optimisation methods - genetic algorithm and FA - revealed that FA provides more stable optimised results with higher efficiency. Using FA, parameters can be updated by minimising an objective function, which is constructed from residuals between measured and predicted structural responses using the expressed relationships. A numerical example of a simply supported composite girder was discussed to illustrate the effectiveness of our procedure. The method was applied to the FE model updating of the Jingzhong Bridge using in situ static and dynamic results; satisfactory agreement was observed between measured and predicted bridge responses.