This paper presents a method for estimating dynamic loading of steel multi-box girder bridges due to moving vehicles, based on an extensive parameter analysis of 216 multi-box-girder bridges. The curved multi-box-girderbridge is modeled as a curved grillage system. The analytical vehicle, simulated as a nonlinear vehicle model with 11 degrees of freedom, is the HL-93 truck as described in the American Association of State Highway and Transportation Officials (AASHTO) specifications. Truck parameters includethe body, suspensions, and tires. The bridge deck surface is assumed to be classed “good” and is simulated using a stochastic process (power spectral density function). The bridge-vehicle interaction model is validated by field test results from two curved steel box bridges. The analytical results show that the torsion impact factors for curved box girder bridges can be relatively high, while moment, shear and deflection impact factors are normally less than those of corresponding straight box girder bridges due to restricted vehicle speed on curved bridges. The proposed simplifiedimpact equations are appropriate for the design of curved steel box girder bridges.
Abstract