Comparative Analyses of Large Diameter Bored Piles Using International Codes-Article

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The study compares the predicted ultimate capacity and load–settlement behavior of large-diameter bored piles using the Egyptian code ECP 202 (2005), German code DIN 4014 (1990), and AASHTO (2005). Predictions were assessed against modified Chin-method estimates from static load tests on 38 piles in Egypt’s Nile Delta and Port Said regions.<br /><br />On average, ECP 202 predicted lower ultimate capacities than the test-based estimates, while DIN 4014 and AASHTO predicted higher values. The differences were not statistically significant, and all three codes showed similar correlations with the test results. However, each code overestimated capacity in 13 of the 38 cases; for those piles, the average overestimation was greatest for DIN 4014 and AASHTO.<br /><br />Tip resistance accounted for about 25–33% of total predicted capacity. Skin resistance calculations varied more widely between codes. Overestimation was more likely when sand friction made up roughly three-quarters or more of the calculated shaft resistance. ECP 202 was generally conservative, but could substantially overpredict capacity in exceptional cases because its tip-resistance method does not directly account for the actual properties of the soil beneath the pile.<br /><br />The authors propose a simplified load–settlement model based on code-calculated ultimate load and recommended settlement, intended to support piled-raft analysis. They conclude that code calculations alone cannot ensure reliable capacity estimates: pile load testing remains essential. These findings apply specifically to bored piles in the study regions.

Keywords

large-diameter bored piles

ultimate capacity

load-settlement behavior

Egyptian code ECP 202

German code DIN 4014

AASHTO 2005

static load tests

modified Chin method

tip resistance

skin resistance