Deflection Prediction of Track‐Slab Construction of High‐Speed Railway Bridge Based on Impact Vibration Testing and Flexibility Identification

Line shape control is the most critical step in the construction of high‐speed railway bridges. The deflection of long‐span bridges (such as cable‐stayed bridges) is more complex as a multipoint elastic‐supported system, especially during track slab construction. Accurately predicting the line shape of the main girder during the track‐slab paving process is an essential prerequisite for ensuring the track regularity of the high‐speed railway. Therefore, this article proposes a method for identifying flexibility and predicting deflections of a multipoint elastic‐supported structure based on impact vibration testing. First, the cable‐stayed bridge model is transformed into a multipoint elastic‐supported model based on mechanics, and its vibration equation is derived. The modal parameters of the vibration equation are solved, and the flexibility matrix of the multipoint elastic‐supported structure model is further deduced. Subsequently, the proposed theoretical method is verified by the finite element model. Finally, the high‐speed railway cable‐stayed bridge, taking the main girder deflection during the track‐slab paving process as an example, is predicted for three cases: no‐track slab, two‐track slabs, and full‐track slabs. The predicted deflection and measured deflection are generally consistent, with an average error of only 6%. The proposed method can be used to determine the deflection of track‐slabs paving and improve construction efficiency.