Evaluation of production models for load rating reinforced concrete box culverts

Analyses of two production-oriented culvert load-rating demand models were performed using live-load test data from three instrumented RC box culverts under four cover soil depths. The demand models were a two-dimensional (2D) structural-frame model and a 2D soil-structure interaction model. As expected, increased sophistication in the soil-structure model compared with the structural-frame model resulted in higher precision and accuracy for predicted moments. The impact of modeling accuracy for sections in a culvert where the demand moments approach zero was deemed practically insignificant. When evaluating model accuracy, it is of first importance that the models predict meaningful load magnitudes. Variations in predicted moment accuracy and precision were not uniform but were a function of the location of the critical section in the culvert structure. Improvements in modeling prediction associated with increased modeling sophistication were seen only when the structural-frame model was very imprecise.