Analysis and rating of reinforced concrete box culverts under various loading and modeling conditions

Loading rating of a bridge is performed in order to determine if the bridge can adequately carry the vehicle traffic that it is expected to experience throughout its existence. Currently, there are two primary methods to load rate bridges; the Load Factor Rating (LFR) method and the Load and Resistance Factor Rating (LRFR) method. Due to a mandate from the Federal Highway Administration (FHWA), the Tennessee Department of Transportation (TDOT) began the process of load rating the reinforced concrete culverts in their inventory. During this process, issues arose about different loading and modeling procedures for rating concrete culverts. Some of these issues included modeling culverts with or without moment continuity and selecting certain load and load factors when the rating methods give more than one option. The two main objectives of this research were to investigate the effect on rating factors from changing the moment continuity at the exterior wall top and bottom connections and to perform parametric studies for certain loads and load factors specified in the LFR and LRFR. These loads and load factors included the horizontal soil pressure, soil interaction factor, coefficient of lateral earth pressure, fill depth multiplier, and the centipede truck.;These objectives were accomplished by comparing the rating factors and applied moments for selected culverts. Culverts from TDOT's inventory that did not have negative moment reinforcement at the exterior wall connections were used for the moment continuity study, and a group of standard culverts with uniform dimensions were used for the load and load factor study.;The results of this study indicate that the use of zero moment continuity to model culvert joints that do not have negative moment reinforcement represents the actual performance of the culverts. When rating culverts, choosing certain load factors can drastically affect and alter the rating factor values for each member of a culvert. The change of the unit weight for the horizontal soil, the coefficient of lateral earth pressure for the horizontal soil and the live load surcharge, the soil interaction factor for the vertical soil, and method used to form a centipede truck configuration can have significant effects on the rating factors depending on the culvert's dimensions and properties. The change of the fill depth multiplier and the point load spacing of a centipede truck configuration does not have significant effects on the rating factors for any culvert.