SYMPOSIA PAPER Published: 29 July 2019
STP161120170170

Combining Static and Dynamic Loading Test Results of Piles

Source

Dynamic load testing is the most economical means of estimating deep foundation behavior under static loads. Unfortunately, this relatively quick and inexpensive test method has limitations: incomplete assessment of time-dependent soil resistance changes, incomplete resistance mobilization, failure criteria that differ from those for static tests, different failure modes in open-ended profiles, and sensitivity to high loading rates. Because of their economy, dynamic loading tests can be done on numerous piles at a site, whereas static loading tests must be limited to one or only a few piles. Modern codes such as American Association of State Highway and Transportation Officials specifications allow for increased resistance factors, equivalent to reduced factors of safety, when several dynamic tests are performed at a site. Even greater reductions of factors of safety are acceptable when the dynamic test is calibrated by comparison with static loading tests performed at the same site or at least under similar pile, soil, and hammer conditions. Exactly how to do such a calibration and how to combine the results of both types of tests is rarely discussed or specified. The calibration procedure is not a simple matter because it has to take into account the reasons for the differences between the two test types. This paper describes how to set up and perform effective test programs. Differences between the static and dynamic tests are explained and classified so that rational and specific recommendations for the test calibration process can be developed.

Author Information

Rausche, Frank
Pile Dynamics, Inc., Cleveland, OH, US
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Details
Developed by Committee: D18
Pages: 520–541
DOI: 10.1520/STP161120170170
ISBN-EB: 978-0-8031-7668-3
ISBN-13: 978-0-8031-7667-6