Experimental Study on Bending-Torsional Coupled Modal Identification of Wide Viaduct

With the rapid development of urban traffic, the viaducts which have the advantage of covering smaller area and three-dimensional traffic capacity have become arteries for urban traffic. Due to the increasing width of the bridge deck, the problem of bending-torsional coupled vibration raised concern. In order to analysis the bending-torsional coupled mode, firstly a box girder finite element numerical example is applied to verify that the stochastic subspace identification method based on ambient vibration can effectively identify the bending-torsional coupled mode of the structure. At the same time it proves that the efficiency of the two ways, using lateral and vertical responses to identify parameters together or separately, is consistent. Then experimental modal identification is conducted on a viaduct, using separate identification method based on stochastic subspace identification. The results show that the bending-torsional coupled mode cannot be ignored for this kind of wide viaduct, which is referential for model updating and dynamic analysis.