Indirect Spatial Mode Shape Identification of T-Girder Bridges Using Contact-Point Response of a Moving Test Vehicle: A Theoretical Study

Indirect bridge modal parameter identification using vehicle responses has been widely studied for two-dimensional bridge model, while rare work is devoted to the indirect identification of bridge spatial mode shape (BSMS). This paper proposes an effective procedure for BSMS identification of the widely used T-girder bridges, in which the closed-form solution is derived based on the vehicle contact-point response. The BSMS is identified using the bridge related components extracted from contact-point responses of a vehicle running at different transverse positions on the bridge. The detailed procedure for the identification of BSMS is introduced, and the feasibility of the method is analyzed numerically. To verify its applicability, the influences of some key factors in the vehicle–bridge system, such as the vehicle speed, the driving position, and the road surface roughness, on the identification results are analyzed. The effect of the bridge damage conditions on the BSMS identification is also investigated. The results show that the spatial mode shapes of T-girder bridges can be identified using the proposed method with high accuracy and efficiency.