Establishment and effect analysis of traffic load for long-span bridge via fusion of parameter correlation

Abstract

Traffic flow is the main driver behind the dynamic response in operation of long-span bridges. To further improve the effectiveness of safety analysis for long span bridges, the bridge dynamic response should be analyzed under traffic flow. This paper investigated the simulation method of traffic flow and the bridge dynamic response under it. Firstly, the potential parameter correlation in the traffic flow was analyzed based on WIM data. Secondly, a refined simulation method of stochastic traffic flow that considers the correlation in vehicle arriving sequence and axle weight (AW) was proposed and validated. The Markov Chain Monte Carlo (MCMC) method and the correlation random sampling Monte Carlo simulation (CMCS) method were used to simulate the correlation of vehicle arriving sequence and axle weight, respectively. Finally, the constructed stochastic traffic flow is used to evaluate the influence of parameter correlation of traffic flow on dynamic response for long span suspension bridges. Results highlight the correlation of traffic flow. For the vehicle arriving sequence, those vehicles with a small quality rarely follow those with a large quality. The vehicles of different types follow certain transfer relationship. The correlation of vehicle arriving sequence can be effectively simulated that the vehicle type distribution and transition probability of the samples are both close to the WIM data. Meanwhile, the correlation of vehicle AW is mainly observed among multi-axle vehicles, and that in two- and three-axle vehicles is not significant. In the bridge application, the proposed method outperforms the MC method in the simulation of multi-axle vehicles. The parameter correlation of traffic flow has obvious influence on the response of the girder of long-span suspension bridge. The distribution of vertical displacement and bending moment of SC is closer to WIM data, and due to the small ratio of live load to dead load, some indexes such as the suspender force are less affected. The consideration of parameter correlation brings the load effect closer to the WIM data, the parameter correlation should be considered in the evaluation of the fatigue life of components, which can positively contribute to the long-term evaluation of bridge response under traffic flow.