Economical design of buried concrete pipes subjected to UK standard traffic loading

Abstract

The British standard (BS) uses the indirect design method to design buried concrete pipes under the effect of traffic load; in this method the laboratory capacity of the pipe is obtained and linked to the field capacity using an empirical factor called the bedding factor. However, the BS design bedding factors have not been rigorously tested. This paper therefore presents a rigorous analysis of the response of buried pipes under the BS traffic loading requirements and tests the robustness of the BS design bedding factors using a validated finite-element model. It was found that the BS bedding factors are overly conservative, with a ratio of calculated values to the design bedding factors ranging from 1·63 to 4·92. This over-conservatism can be attributed to an oversimplification in the BS methodology for calculating the force applied to the pipe. Therefore, new bedding factors have been proposed utilising the evolutionary polynomial regression analysis technique. These bedding factors implicitly account for the error due to the oversimplification in the design force calculation. Hence, more economical and robust designs can be achieved by using the new bedding factors.