Samenvatting
The dynamic characteristics of girder bridges can be evaluated from measured live load strains in girders resulting from regular truck traffic. The evaluation includes the determination of the dominant vibrational modes and the corresponding damping ratios. Results from a single-span and a three-span skewed bridge show that both are dominated by a flexure mode of vibration with a damping ratio of about 2%. A beam model is used to simulate the dynamic response of the single-span bridge to a test truck. The results compared well with the measured stresses.