MODAL ANALYSIS OF THE CUMBERLAND RIVER BRIDGE ON I-24 HIGHWAY IN WEST KENTUCKY

摘要

The paper presents a dynamic analysis of a plate girder bridge over the Cumberland River on interstate I-24 in Western Kentucky. The two girder steel bridge consists of six spans including the approach spans. The total length of the bridge is 1671 feet, and the width is 39.5 feet. The structural dynamic properties of the three main spans were obtained by conducting field ambient vibration testing and three-dimensional finite element modeling with SAP2000. Both the peak picking method in frequency domain and the stochastic subspace identification method in time domain were used for the system identification induced by ambient vibration. The finite element analysis involved discretization of the bridge using beam elements. An eigenvector analysis provided the natural frequencies and mode shapes in the orthogonal directions. These were calibrated to match the field mode shapes and natural frequencies of the bridge. The calibrated finite element model that reflects the current structural condition will be further used to the seismic evaluation/retrofit of the bridge.