INFLUENCE OF RAILINGS STIFFNESS ON WHEEL LOAD DISTRIBUTION IN THREE- AND FOUR-LANE CONCRETE SLAB BRIDGES

The American Association of State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO LRFD) do not account for the presence of railings in the analysis or design of highway bridges. This paper presents a follow-up parametric investigation of the influence of railing stiffness on the wheel load distribution in simply-supported, one-span, threeand four-lane reinforced concrete slab bridges using the finite-element analysis (FEA). A total of 48 bridge cases are modeled using refined 3D FEA and bridge parameters such as span lengths, slab widths, and railings that were varied within practical ranges. Various railings stiffness were considered to be built integrally with the bridge deck and placed on both edges of the concrete slabs. The FEA wheel load distribution and bending moments are compared with reference bridge slabs without railings as well as to the AASHTO design procedures. According to the FEA results, the presence of railings reduces the longitudinal bending moment in the concrete slabs by 25% to 60% depending on the stiffness of the railings in oneand two-lane reinforced concrete bridges. However, when considering threeand four-lane bridges, the presence of railings reduced the longitudinal bending moment in the concrete slab by a range of 10% to 32% depending on the stiffness of railings. The results of this investigation will assist bridge engineers in better evaluating the load carrying capacities of multi-lane concrete slab bridges using 3D FEA and account for the contribution of railings. The presence of railings can also be considered a possible alternative for strengthening existing concrete slab bridges.