Evaluation of compression load test interpretation criteria for driven precast concrete pile capacity

Abstract

An extensive evaluation of capacity interpretation criteria is presented for driven Precast Concrete (PC) piles under axial compression loading. A database of static load tests for round and square cross-section piles under both drained and undrained loading was developed and utilized in the analysis. The compiled data are generalized into four groups (round — drained, square — drained, round — undrained, and square — undrained) to examine the differences in their behavior. Generally, similar trends for each criterion are noted for the four groups. Statistical analyses show a decreasing COV with increasing pile displacement, and the drained load tests show less variability than the undrained load tests. For drained loading, somewhat higher interpreted capacities are exhibited by round piles than by square piles. In addition, a slightly stiffer normalized load-displacement curve is shown for the drained loading compared to the undrained loading. The drained and undrained databases are further sub-divided by hammer type (drop, air/steam, diesel, and hydraulic) to explore the effects of driving energy and driving resistances on pile capacity. Based on these analyses, the relative merits and interrelationships of these criteria are established, and design recommendations for the use of these methods are suggested in terms of normalized capacity and displacement.