Influence of railings stiffness on multi-span multi-lane wheel load distribution in concrete slab bridges.

Abstract

The presence of railings or parapets acting integrally with the bridge deck have the effect of stiffening and attracting load to the slab edge and therefore altering the lateral wheel load distribution on highway bridges, which would result in increasing the load-carrying capacity of concrete slab bridges. The current research dwells on a previous research conducted on One-span bridges, and extends the analysis to study the influence of varying the railings size or stiffness on wheel load distribution, as well as on the load-carrying capacity of straight two-span concrete slab bridges. Typical two-span, simply supported, multi-lane (One to four lanes), straight reinforced concrete slab bridges are considered. The finite-element method is used to investigate the effect of span length and slab width, and to calculate the wheel load distribution on the bridge slab at the critical section. AASHTO design trucks loads are placed transversally and longitudinally to produce maximum moments at the critical section of the slabs. Various configurations of railings sizes-stiffnesses on either or both edges of the slab are considered for straight bridges, where the cases with no railing will serve as reference cases. The wheel load distribution on the bridge slab at the critical section for the reference cases and for cases with railings are calculated and compared. The results are also assessed and evaluated with AASHTO current procedures which do not include railing stiffness as a criterion in design, and recommendations are made to assess the influence of railings on straight bridges. This research will assist structural engineers in better designing new straight concrete slab bridges, or evaluating more precisely the load-carrying capacity of existing bridges in the presence of railings. In addition, the approach adopted in this research can also be considered as an adequate and practical method for strengthening and rehabilitating concrete slab bridges. Further, the findings from this and previous research in th