Different Approaches to Rating Slab Bridges

The effects of different approaches to rating reinforced concrete slab bridges are explored by using an existing bridge as an example. Nonlinear finite‐element analysis (NLFEA) has been conducted on a field‐calibrated model of the bridge to obtain the ultimate capacity, which is compared with the rating factors obtained from American Association of State Highway and Transportation Officials (AASHTO) guidelines. The demand used to obtain the rating factor depends on how the structure is idealized in the analysis. The capacity can be interpreted at either the local level (material strength or cross‐sectional strength) or at the global level (failure of the structure due to attainment of a collapse mechanism or due to regional shear failure). It is observed that different approaches yield significantly different rating factors and the reasons for the noted differences are discussed.