Assessment of the effect of fill depth and span on the conservativeness of the 2D method of analysis of box culverts in comparison to the 3D method

Abstract

This research study aimed to investigate the effect of fill depth and span on the conservativeness of the 2D method of analysis of box culverts in comparison with the 3D method. A total of 80 models were made using Midas Civil, which comprised 40 models in 2D and 40 in 3D. These were single cell box culverts analyzed and designed according to EN 1992 and PD6694-1:2011. The total mass of each model was computed, and graphs were plotted as shown in this report. The results showed that the 2D and 3D analysis methods give similar results in terms of quantity of steel regardless of the span length for a culvert with 1.2m fill depth. Additionally, the 4m span gave the same quantities of steel for the 2D and 3D analysis at 3.5m of fill depth. Therefore, it was concluded that the 2D method could be adopted for all spans with 1.2m of fill. Additionally, the 2D method could also be adopted for a 4m span culvert with 3.5m of fill. For all other cases, the 3D analysis method should be used.