Behavior of horizontally curved I-girder bridges are complex and its interaction analysis is difficult. In this study, extended three-dimensional finite element interaction analyses were conducted parametrically. The bridge is modeled in detailed with solid and shell elements and vehicle is simulated as a nonlinear model according to HS20-44 design truck. Road roughness profiles are generated from power spectral density and cross spectral functions. By using these models, natural vibration and forced vibration analyses carried out in parametric study, are extensively investigated. The analytical results are significant and give some useful information regarding the impact factor of the studied bridge which could be much helpful for practical designer
