Experimental and Finite Element Analysis of Deep Curved Box Girders: Impact of Concrete Strength and Geometry

Reducing the ratio of box girders' span to their height reduces bending moments and makes them deep members that are controlled by shear behavior. The presence of horizontal curvature generates torsional moments and different deflection between the outer and inner web as a result of twisting. Two experimental specimens with the same dimensions were cast and tested, one straight and the other horizontally curved. The two specimens were numerically modeled using the ABAQUS software for the purpose of verifying the numerical model to study more parameters. The finite element analysis showed a good agreement with the experimental values with a difference of (98-99) %, (94-97)% and 103% of the experiment for ultimate loading, deflection and twisting angle, respectively. It also showed stress paths that match the experimental and theoretical results that explain the behavior of deep beams, such as the Strut and Tie method (STM). The effect of compressive strength, whole width, and the width of the bearing and supporting plates was studied. Results showed that increasing the concrete's compressive strength by about 40-120%, increased the load capacity and decreased its deflection by approximately 6-14% and 3-15%, respectively. The deep box section torsional resistance increased when its width was increased by approximately 17–50%, although this had no significantly affect on the load capacity level. A reduction of 17-33% in the width of the loading and supporting bearing plates caused a 6-16% drop in load capacity besides a notable decrease in stiffness.