The structural impedance approach is extended to study the transient response of bridges due to general traffic conditions. A computer code STRIM is developed to study the dynamic behavior of bridges subjected to several types of traffic loads. It is demonstrated that the present approach has the capability of modeling the complete dynamic interactions between the vehicles and the bridge structure. More importantly, a bridge can more readily be modeled as a two or three dimension structure. More realistic traffic loads such as a sequence of moving vehicles with variable speeds and accelerations can be included.
The accuracy of the algorithm is verified by comparing the numerical results calculated with the experimental results on the three and six-span beams with intermediate elastic supports.
The dynamic response of cable stayed bridges is studied by incorporating the flexibility function of the structure into the computer program STRIM. Both the static and dynamic analysis of cable stayed bridges are formulated and programmed based on an approximate method and a more exact method of analysis.
The complete response histories for the girder, tower and cables due to the effect of vehicle velocity, girder damping and traffic load are obtained and the impact factors for bridge components are computed. These may have important applications in assessing the fatigue life expectancy of bridge components and in determining the safety and the allowable traffic condition of a bridge structure.
