Calculating Local Force of Corrugated Steel Culvert Buried at Shallow Cover Depth Using a Thrust Modification Factor | Journal of Bridge Engineering | Vol 28, No 1

AbstractCurrent practice only considers the net (average) thrust for in-service engineering assessment of buried corrugated steel culverts (CSCs). In this study, numerical simulations have demonstrated, for shallow cover depth conditions (H/D < 2), the importance of local peak thrust and combined load effects (i.e., thrust and moment), which occur between the CSC shoulder and crown locations. These observations are supported by independent, third-party, full-scale, physical modeling studies. A global sensitivity analysis was conducted to identify the influential variables, assess the significance of any interaction, and estimate the influence on the predicted response. Based on this analysis, a limit state function for combined load effects and modification factor to account for the local peak thrust force was developed. The reliability index for the proposed coefficients was also established.Practical ApplicationsFor culverts buried at depths greater than twice the culvert diameter, current engineering practice can be used, with confidence, to estimate the average (net) circumferential force (thrust) developed in the culvert wall. As the culvert burial depth is reduced, there is less confidence in predictable outcomes with shallower cover depth where the top of the culvert (crown) is located closer to the ground surface. In this study, numerical simulation tools have shown that current practice underestimates the magnitude (value) of the circumferential forces developed in comparison with numerical modeling predictions. The numerical models demonstrate that the response of shallow buried culverts is influenced by both circumferential forces and bending forces where the peak local force is greater than the net thrust. A mathematical equation is developed that accounts for the changes in the culvert circumferential force and bending force with burial depth that can be used to guide engineering design.


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