Finite element analysis on induced stresses in horizontally curved box girder flange

The stress distribution in a horizontally curved box girder flange is quite complicated due to the inherent coupling of vertical bending and torsion plus stresses induced box distortion. Uncontrolled development of the distortional normal stress has a significant detrimental effect on the strength of a box girder. Through studies have been conducted to examine the longitudinal stresses on the bottom flange of a box girder with a horizontally curved geometry, the past studies do not provide sufficiently detailed design speculations to guide a simple determination of cross-frame design parameters. Thus, numerical analysis studies were conducted by using the finite element method to examine the effect of the cross-frames on the induced normal stresses in a tub girder. A typical curved box girder bridge currently constructed in the U.S was simulated and 3-dimensional finite element analyses were performed. Through a series of hypothetical bridge analyses, variation of the induced non-uniform stress along with corresponding diaphragm spacing is numerically examined and an optimum design for the cross-frames is proposed.