Bridge Structures 15 (2019) 197–205 DOI:10.3233/BRS-190159 IOS Press 197 Effect of railing deterioration on load carrying capacity of concrete slab bridges F. Darwich a , K. Tarhini b and M. Mabsout a,∗ a American University of Beirut, Beirut, Lebanon b U.S. Coast Guard Academy, New London, CT, USA Abstract. Recent studies quantified the increase in load-carrying capacity of bridges by 45% due to the presence of concrete railings. These railings are subject to deterioration due to accidents. This parametric study quantifies the effect of railing deterioration and its impact on load-carrying capacity of bridges. A total of 112 bridge cases were analyzed using finite element analysis (FEA). The FEA results for slab moments were calculated and compared to reference cases and AASHTO procedures. FEA moments for bridge cases with one railing fully deteriorated compared well with AASHTO, with the exception of one-lane bridges where the overestimation by AASHTO reaches 20% for 1 ft deteriorated length, and decreased to 10% as the deterioration length increased to 8 ft. Railing deteriorations also changed FEA edge moments significantly by underestimating moments by 40% for two-lane bridges. This research can help engineers quantify the effect of railings on load carrying capacity of bridges. Keywords: Concrete slab bridges, railing deterioration, finite-element analysis, AASHTO procedures, load-carrying capacity, wheel load distribution 1. Introduction The design of highway bridges in the United States conforms to the American Association of State Highway and Transportation Officials (AASHTO) Standard Specifications for Highway Bridges (AASHTO Specs 2002) or AASHTO Load and Resistance Factor Design (LRFD) Bridge Design Specifications (AASHTO LRFD 2012). The current AASHTO procedures do not consider the effect of railings that are built integrally with bridge deck in the analysis and design or in evaluating the load- carrying capacity of concrete slab bridges. These railings have the effect of stiffening and attracting load to the slab edge and therefore altering the lateral wheel load distribution on concrete slab bridges. Mabsout et al. (2004) investigated single-span, simply-supported reinforced concrete slab bridges using finite-element analysis (FEA). Results indica- ∗ Corresponding author. M. Mabsout, American University of Beirut, Beirut, Lebanon. E-mail: mounir@aub.edu.lb. ted that AASHTO Standard Specifications moments overestimate the FEA moments for short spans and one-lane bridges but agreed with FEA moments for short-span bridges with two or more lanes. It was also found that AASHTO Standard Specifications underestimated the FEA moments for longer spans. However, for AASHTO LRFD procedure, it overes- timated the FEA moments for all bridge cases. In addition, several published studies were conducted by investigating the influence of sidewalks and railings on wheel load distribution in steel and prestressed girder bridges which was shown to increase the stiffness of the superstructure and increase the load- carrying capacity of these bridges (Akinci et al. 2008, Chung et al. 2006, Conner & Huo 2006, Eamon & Nowak 2002, Mabsout et al. 1997). Previous studies have shown and quantified the increase in the load-carrying capacity of bridges due to the presence of railings, which tends to be sig- nificant depending on the railing size and bridge geometry. Recently, a parametric investigation by 1573-2487/19/$35.00 © 2019 – IOS Press and the authors. All rights reserved