Dynamic Evaluation and Retrofitting of a Partial-Composite Prestressed Concrete Girder Bridge with Vibration Issues

There are no prescribed methods in governing design specifications for limiting excessive traffic vibrations in highway bridges. This is indirectly addressed through deflection limits. However, dynamic parameters such as acceleration and frequency are better predictors of the severity of bridge vibration. This study employed these two critical parameters to quantify bridge vibration and develop retrofit strategies for a partially composite concrete highway bridge (test bridge) with excessive vibration. The bridge, built in 2011, in McKinney, Texas, was found to have excessive vibration, cracking, and potholes on the concrete deck. Nondestructive evaluation and diagnostic load testing revealed severe delamination in the composite deck and significant loss of full deck-girder composite action. Ambient vibration testing was conducted to obtain the maximum acceleration of the bridge superstructure and compared with values from two other nearby similar bridges with no noticeable vibration issues. The maximum transverse and vertical accelerations of the girders and the deck in the test bridge were higher than those in similar bridges. The bridge natural frequency was calculated from the response of a fully loaded passing truck on the deck. Due to stiffness reduction, the frequency was considerably lower than the acceptable minimum value per literature. A calibrated finite-element model of the bridge was developed, through which various retrofitting methods were investigated for an optimal solution to mitigate the excessive vibration.