Development of a Quick Design Method for Composite Concrete Slab-Over Steel Box Girder Bridges for Project Bidding

In bridge analysis, the beam analogy method is used to analyze girders for the longitudinal load effects of live loads. Designers calculate the maximum bending moment (MT), and the shear force (VT), of a bridge girder under truck loading and use the truck load fraction (FT) to generate the design longitudinal live load effects. This Report presents structural analysis and design of different composite concrete slab-over multi-spine steel box girder configurations subjected to CL-W truck loading. Bridge geometries include single-, two-, three-, and four-span girder arrangements. Bridge widths ranged from 7 m (1 lane) to 24 m (6 lanes), with spans ranging from 20 m to 80 m. Equations developed by others were used to represent values of the maximum shear, deflection and bending moments experienced by the girder due to truck loading conditions. This study also included updating and verification of a software developed by a Ph.D. student, used to perform composite steel box girder design. The software optimizes the box girder size based on the CHBDC design procedure. Using the developed software, a parametric study was conducted to determine the required moment of inertia of the bare steel section, composite moment of inertia and steel web area to satisfy all design requirements. Empirical equations for these three properties were developed to assist bridge designers in estimating steel box girder section sizes for contract bidding.