Impact of shear rating factors for reinforced concrete culverts and enhancement of TDOT Culvert Rating Aids

Engineers rate structures per member to estimate the ability of a structure to resist loads and to take appropriate actions if necessary. In the rating process, rating factors are determined to quickly assess whether structural members can stand up to expected dead and live loads. As long as rating factors are above 1, the capacity of a structural member is considered adequate. This thesis uses different methods from three specifications, namely AASTHO LFD and LRFD as well as ACI, and two structural analysis programs, BRASS Culvert and Response-2000, to estimate shear capacity. Additionally, Mathcad was used to compute load models, and STAAD Pro was used to determine member forces necessary to compute shear capacities and shear rating factors. When comparing the calculations of shear capacity for specifications and programs to test results, it was noted that equations and programs that took axial forces into account produced higher shear capacities on average. Currently, the culvert analysis program known as BRASS Culvert appears to be conservatively estimating shear capacity of members as it does not consider axial forces in any of the shear equations that it uses. Through the shear capacity and shear rating factor analyses, it was determined that small increases in shear capacity can lead to noticeable increases in shear rating factors. With the results clearly showing that shear capacity is conservatively estimated on average by the specification equations used in BRASS Culvert, it was concluded that shear rating factors, as calculated by BRASS Culvert for the TDOT Culvert Rating Aids, may be overlooked. The TDOT Culvert Rating Aids were developed to assist in the rating of reinforced concrete culverts in Tennessee. As described in this thesis, the Rating Aids were embellished with additional search features and other items to aid in their use.