IDENTIFICATION AND UPDATING FOR THE THREE-DIMENSIONAL FINITE ELEMENT MODEL OF A LONG SPAN STEEL SKYBRIDGE

摘要

An identification and updating procedure for the three-dimensional finite element (FE) model of a long span steel skybridge is presented in this paper. Located at an elevation of 90 m, the skybridge is one of the six skybridges of Hangzhou Citizen Center, which is a hexadic-tower tall building. The modal data of the skybridge is first estimated using output only identification method, and sensitivity-based updating method is then applied to update the three-dimensional FE model based on the estimated modal data. For the modal data identification, a time domain least square method and a data smoothing method were applied for pre-processing the recorded acceleration time histories. The averaged normalized power spectral density was then used in the peak-picking method to identify the natural frequencies. The updating algorithm is composed of sensitivity analysis and Bayesian estimation, and the parameter perturbations are estimated using a constrained optimization method. It is found that far better matches can be reached between the updated and estimated dynamic characteristics by using the proposed identification and updating procedure.