Application of Reliability-Based Guidelines for Considering Pile Setup in Missouri

Pile setup has been commonly observed to result in significant increases in pile resistance with time after the end of initial driving. Despite the abundance of evidence for pile setup, harnessing the setup resistance in a reliable manner is challenging. As a result, setup resistance in some cases is neglected, which leaves valuable resistance unutilized, and in other cases, it is relied upon for design but requires costly delays associated with performing restrikes. Recent research for the Missouri Department of Transportation resulted in development of load and resistance factor design guidance for relying on pile setup without restrikes. The proposed design guidance is based on reliability analysis of high-strain dynamic test results from project sites across northern Missouri with restrikes. This paper briefly summarizes the research and proposed guidance before presenting detailed examples applying the guidance. Results of the examples demonstrate the proposed guidance results in reductions in pile length as great as 27%, but that further reductions are achieved with restrikes. The findings demonstrate the value of developing agency-specific LRFD procedures, which reduce the challenges and variability of national design provisions.