Effects of Random Road Roughness on Dynamic Impact Factor of Cable-Stayed Bridge Subjected to Moving Vehicle

In this study, a two-dimensional vehicle-bridge dynamic interaction model is presented to analyze the dynamic impact factor of a cable-stayed bridge in service by considering the effect of the random road surface roughness. The bridge system including girder, towers, and cables is discretized by using the finite element method. The common model of random road roughness vertical profiles is applied in the form of a stationary and ergodic Gaussian process in space. Random samples of road roughness vertical profiles are generated with the Monte-Carlo simulation method. A two-dimension vehicle model with 4 degrees of freedom is adopted. Based on the d’Alembert’s principle, the coupled equation of motion of cable-stayed bridge and vehicle are established by combining both the bridge and vehicle using the interaction force relationship at the contact point. Solutions of the coupled equation of motion in the time domain are solved using the Runge-Kutta-Merson method. The accuracy of numerical results is validated by field test results of the Pho Nam cable-stayed bridge at Danang city, Vietnam. Additionally, the influences of random road roughness on the dynamic impact factor of the bridge were discussed in detail. The results of the dynamic impact factor study show that bridge design codes currently underestimate the dynamic response of the bridge for moving vehicles under different road surface conditions. The findings of this study can be utilized for future design.