Value of Methods for Predicting Axial Pile Capacity

Abstract

The purpose of this paper is to compare the value of predicting capacity using dynamic formulas, wave equation analysis, and dynamic monitoring without load tests. A database of pile load test results is used to quantify the precision associated with predictive methods. These methods are quantified and ranked using a “wasted capacity index” (WCI) to quantify the effect of precision. The WCI is a measure of how inefficiently a method predicts capacity. A precise method will be very efficient and accordingly have a low WCI. On the other hand, a less precise method requires a more conservative design and thus a greater WCI. The value of the wasted capacity index is calculated from the precision of the method and the reliability required for the pile foundation. The WCI is presented for the following methods: Engineering News (EN) formula, Gates formula, wave equation analysis program (WEAP), measured energy (ME) approach, pile driving analyzer (PDA), and CASE Pile Wave Analysis Program (CAPWAP).