Comparison and application of two time domain methods analysis to modal parameter identification of Songhuajiang River highway-railway bridge

In this paper, comparison and application of two time domain modal parameter identification methods of ERA and SSI in a steel truss bridge is discussed. Firstly, multidirectional comparison and analysis of structural modal parameter identification under environment excitation to the bridge are carried out. Then finite element model of the Songhuajiang River highway-railway bridge is established by MIDAS CIVIL, and the modal analysis of the structure is carried out. The first ten order modes of the structure are obtained, and some characteristics of the first ten order modes are analyzed and compared. And combining the partial trend of the finite element modal analysis, the vibration experiment of the Songhuajiang River highway-railway steel bridge under the environmental excitation is tested. Then the modal parameters of the structure are calculated, analyzed and compared through the ERA method and SSI method based on the state space model. Finally the accuracy of the two modal parameter identification methods is tested, and the feasibility of the two methods applied in the steel truss bridge structural analysis is verified.