Dynamic Analysis of Existing Continuous Bridge

Abstract

This paper presents the investigation of the effect of dynamic loads on the dynamic amplification factors (DAFs) of an existing continuous bridge. A three-dimensional analytical model to idealize the vehicle and a finite element model to analyze the bridge have been developed. Experimental testing of this existing bridge has been conducted by the Ministry of Transportation, Quebec. Two vehicle models, having seven and 11 degrees of freedom with and/or without trailers, are considered in the analysis of the interaction between the bridge and vehicles. Based on International Standards Organization specifications, the road-surface roughness of the approach roadways and bridge deck is generated from the power-spectral density function for very good, good, and average roads. The solutions obtained from the present models are compared with the experimental results for different vehicle speeds. The DAFs are computed from the present finite element model for three different types of measurements (displacements, strains, and reactions). The numerical results show that the DAFs computed with displacements are less than those estimated from strains and reactions. It is concluded that current design codes tend to underestimate dynamic amplification factors, especially for long-span continuous bridges.