Closure to the Discussion of Interpretation of Augered Cast-in-Place Pile Capacity Using Static Loading Tests-Article

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The authors respond to concerns about their analysis of static load tests on augered cast-in-place (ACIP) piles, arguing that their data and interpretations were sound. They show that the ratio between elastic and initial compression slopes varies with pile slenderness: for slenderness ratios below about 20, the elastic slope is generally steeper, while the relationship continues to change for longer piles.<br /><br />The authors advise against using the Davisson method to interpret ACIP pile failure loads. They argue it was developed for driven piles and is sensitive to uncertain assumptions about pile stiffness, steel content, grout strength, and concrete modulus. Consequently, Davisson capacity should not be treated as a reliable or interchangeable reference for other capacity interpretations.<br /><br />The L2 capacity is also affected by test conditions. In particular, the ratio of L2 capacity to Davisson capacity depends on the maximum displacement imposed during the test; insufficient displacement can make L2 difficult to determine. The ratio also varies with slenderness, which serves as a proxy for axial stiffness. Differences between the authors’ results and the discussers’ findings are therefore largely attributed to the different slenderness distributions in their databases.<br /><br />The authors conclude that reliable interpretation of ACIP pile failure loads requires accounting for slenderness and axial stiffness, as well as ensuring that tests impose sufficient displacement. They agree that only original load-test data should be used to assess the initial slope.

Keywords

ACIP piles

static load tests

Davisson method

pile slenderness

elastic slope

initial compression slope

L2 capacity

axial stiffness

failure load interpretation

load-test data