Effect of Potholes on Load Distribution in Concrete Slab Bridges

This paper presents a parametric study of the effect of potholes on load distribution in reinforced concrete slab bridges using finite-element analysis (FEA). Parameters such as the span length, slab width, pothole location, and wheel load conditions on simply supported one-span reinforced concrete slab bridges were investigated. Four typical span lengths were considered in combination with one, two, three, and four lanes. A total of 65 highway bridge study cases were analyzed. It was assumed that the bridges were stand-alone structures carrying one-way traffic. Design trucks were placed close to one edge of the slab, with the absolute minimum spacing between the trucks in order to predict the worst loading conditions. Previous studies validated the use of the AASHTO standard specifications design procedures when designing slab bridges. A typical bridge was selected to determine analytically the optimum thickness and critical location of the pothole(s) in any lane at midspan. The presence of one or two potholes $[0.6m\times 0.6m(2\mathrm{ft}\times 2\mathrm{ft}\left)\right]$ in the first two lanes created at the midspan of a bridge increased the maximum longitudinal bending moment by about 25% when compared with FEA results of slabs with no potholes, and by as much as 70% when compared with the AASHTO standard specifications. However, the new AASHTO LRFD design procedure overestimates the design moment in the concrete slabs with one or two potholes by about 20%. Therefore, the AASHTO LRFD design approach appears to account for the potential deterioration in the design of new concrete slab bridges. This paper will assist bridge engineers in comparing the two AASHTO design procedures as well as performing a realistic evaluation of the load carrying capacity of existing highway bridges.