The reliability-based calibration of dynamic load allowance (DLA) of bridge is performed by numerical analysis of vehicle-bridge dynamics. The road surface roughness, bridge dynamics, and vehicle dynamics are included in the simulation program. The road profiles are generated by using a Fourier transform of the power spectral density function. The bridge superstructure is modeled three dimensionally using beam, truss, and shell finite elements. Modal equations of motion are formulated by using 50 fundamental modes of vibration. Three different types of vehicles are modeled using the tire enveloping model. In the calculation of DLA, typical plate-girder bridges and prestressed concrete beam bridges with various span lengths are considered. For each bridge, 10 sets of road profiles are generated and hundreds of simulations are performed to obtain the mean and the coefficient of variation of DLA. Based on the resulting statistical parameters, the DLA of bridge is calibrated.
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