Effect of Centrifugal Force on the Structure of the Overarching Bridge ( Box – Girder )

Abstract

Horizontally curved bridges, often utilizing box-girder superstructures, are essential components in modern highway interchanges. However, their curved alignment introduces significant centrifugal forces generated by moving vehicles. This research provides a structural analysis of the effect of this centrifugal force on the behavior of a curved overarching bridge. The study employs the Finite Element Method (FEM) to create a 3D model of the continuous box-girder structure. The model is subjected to standard design loads (dead load, live load) in combination with the centrifugal load, which is applied as a transverse horizontal force. The analysis focuses on quantifying the unique stresses induced by this lateral force. The results demonstrate that the centrifugal force is a dominant load case, inducing significant torsional moments (twisting) along the box-girder's longitudinal axis and substantial lateral shear forces at the piers and abutments. These forces also cause a differential vertical reaction at the bearings, impacting the overturning stability. This study concludes that neglecting the centrifugal force in the design of curved box-girder bridges leads to a critical underestimation of torsional stresses and lateral displacements, compromising the structure's safety and serviceability.