Influence of railings stiffness on 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. This may also result in increasing the load-carrying capacity of bridges. The current research presents a parametric study to investigate the influence of typical integral railings on wheel load distribution as well as on the load-carrying capacity of skewed concrete slab bridges. Typical one-span, simply supported, multi-lane (one to four lanes), skewed reinforced concrete slab bridges are considered. The finite-element method is used to investigate the effect of span length, slab width, skew angle 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 on either or both edges of the slab are considered for straight and skewed bridges. Straight bridges with no railings 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 railing and-or skewness are calculated and compared. The results are also assessed and evaluated with AASHTO procedures, and recommendations are made to assess the influence of railings on skewed bridges. This research will assist structural engineers in better designing new straight and skewed 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 skewed concrete slab bridges.