Baseline finite element modeling of a large span cable-stayed bridge through field ambient vibration tests

A baseline finite element model is a reference in structural damage detection and long-term health monitoring. An ambient vibration measurement based procedure is presented to develop such a baseline model for a newly constructed Qingzhou cable-stayed bridge over the Ming River, Fuzhou, China. A 605 m main span of the bridge is currently the longest in the world among all completed composite-deck cable-stayed bridges. The procedure includes several tasks: finite element modeling, field ambient vibration testing, parametric studies and model validation. It is demonstrated that the ambient vibration measurements are enough to identify the most significant modes of large span cable-stayed bridges with a low range (0-1.0 Hz) of natural frequencies of interest. Some important issues in the modeling of such a complicated bridge, such as the initial equilibrium configuration due to dead load, geometrical nonlinearities, concrete slab, the shear connection of the composite deck, and the longitudinal restraints of the end expansion joints, have been clarified. The developed three-dimensional finite element model of the bridge has achieved a good correlation with the measured natural frequencies and mode shapes identified from field ambient vibration tests.