Live load analysis under assessment reference period for in-service bridge basing on load survey

The aggravated service performance attenuation and substantially reducing of the service life for the highway bridge are caused by the overloading and heavy traffic load phenomenon on the highway. Then the bridge evaluation must consider the actual traffic vehicle load condition. Furthermore, the service time of the bridge, involving the technology assessment of bridge structure, also determine the change of the assessment reference period and the load effect of the bridge. Based on the vehicle load survey data and its statistical analysis measured in Luogang Section of No. 107 National Highway, the probability distribution function of the category vehicle load and the representative values of related parameters are obtained. Using the statistical analysis of vehicle loads measured results, a simulation program for the random fleet across the bridge was compiled, and the load effect of the bridge under the simulated random fleet load is calculated. It presents the conclusion that the mid-span moment of simply supported beam bridge of different span follows the gamma distribution, and the distribution parameters are also calculated. Through the analysis for the service life and the assessment reference period of the bridge, a calculating method for the bridge assessment reference period is presented. Then, basing on the load effect calculated by the survey data simulation, the live load effect variation law of the changed assessment reference period under different service life of bridge can be presented.