Research On Traffic Load Stochastic Process Model Of Existing Bridge

Along with the increasing of the aging bridges in number all over the world, assessment of existing bridges becomes a major subject in the field of bridge research, and the research of stochastic model for traffic load on existing bridge is a significant ingredient of this topic. Combining with the characteristics and the principle of analysis on existing bridges, the equipollent load, the mathematical model and the stochastic model for traffic load on existing bridge are studied. The main works are as follows:1) The developingt history of the traffic load on bridges is represented. Typical bridge codes in some countries are discussed and these traffic load models are comparative analyzed. Analysis shows that the influence of layout axle for the total traffic load effect on bridge gradually becomes smaller with the increase of bridge span. So most national norms use the distributed load as the equipollent load of traffic load. 2) Some major mathematical models for the traffic load are discussed and analyzed, with the characteristics of the process which traffic pass bridges. It shows that the stochastic point process is more reasonable to describe the process which traffic pass bridges. Finally, the application of several major stochastic processes for building the traffic load models of bridges is studied.3) It is discussed that the traffic load model for designing bridges with filtration poisson stochastic process and filtration weibull stochastic process, the traffic load effect model for existing bridges with stationary binomial stochastic process and the traffic load effect model for large-span bridges with stationary normal stochastic process. These models are deduced and their shortages are also generalized.4) Based on the characteristics of the process that traffic pass existing bridges and the currently available statistics on traffic load in china, the traffic load effect model for the existing bridges with equilibrium renewal process is built. The ideal vehicle convoy is built after the uniformly distributed load is used as the equipollent load. With the maximum function of influence line area under the vehicle convoy, the probability of specific vehicle convoy passing influence line alone and the total weight distribution of specific vehicle convoy, the maximum probability distribution of traffic load effect and under return perild are obtained. Finally, this load model is applied to the example.