This document presents a parametric study on the behavior of box-girder bridges using finite element analysis. Rectangular and trapezoidal cross-section box girders were modeled and analyzed for different depths and span lengths. The key findings are: 1) Increasing depth leads to higher bending moments and lower longitudinal stresses in the top and bottom flanges for both cross-section types and span lengths. 2) Trapezoidal cross-sections experience higher bending moments and lower stresses compared to rectangular cross-sections of the same depth. 3) Continuous spans experience higher positive bending moments and lower negative bending moments compared to simply supported spans.