INFLUENCE OF RAILINGS STIFFNESS ON WHEEL LOAD DISTRIBUTION IN ONE- AND TWO-LANE CONCRETE SLAB BRIDGES

Abstract

The American Association of State Highway and Transportation Officials (AASHTO) Load
and Resistance Factor Design (AASHTO LRFD) do not account for the presence of railings as integral parts of
highway bridges. This paper presents the parametric investigation of the influence of railings stiffness on the
wheel load distribution in simply-supported, one-span, one- and two-lane reinforced concrete slab bridges using
the finite-element analysis (FEA). A total of 80 bridge cases are modeled and bridge parameters such as span
lengths and slab widths were varied within practical ranges. Various railings built integrally with the bridge deck
are 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 slabs by 25% to 60%
depending on the stiffness of the railings. The results of this investigation will assist structural and bridge
engineers in better designing or evaluating concrete slab bridges in the presence of railings. This can also be
considered to be a possible alternative for strengthening existing concrete slab bridges.