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Figure C Lateral deflection versus depth profiles for drilled shaft #3. The compressive and tensile strains measured in drilled shaft #4 are presented
in Figure C and Figure C, respectively. A large increase in tensile strain was recorded at the depth of 8 feet when the load increased from 510 kips to 582 kips (Figure C. It is inferred that this marks the onset of concrete cracking. One of the outcomes of this test for use in design would therefore be to recognize the requirement for additional steel reinforcement in this upper zone to control the deflection and limit cracking of the concrete.
By using the piecewise polynomial
curve fitting technique, the p-y curves at two depths (3 feet and 11 feet) for Shaft #4 are derived (Figure C. Commercially available software is used to predict the deep foundation load versus deformation response fora particular
standard p-y relationship, or user defined p-y relationship where site specific data from tests exist. With a p-y relationship derived
from a lateral load test, the software can be used to evaluate the computed load deflection response compared to the measured response. A practitioner may then adjust the soil parameter values input to the software to calibrate the soil model with the test derived p-y curve relationship. In this way, the designer has a predictive tool to evaluate the foundation design under other
load cases and geometries, knowing that the soil parameters for the site in conjunction with the p-y model in the software are replicating the performance of the test. Figure C provides an example plot of a load versus deflection prediction for the top of the drilled shaft. The curve obtained from the lateral load test data is in close agreement with the results using the Reese (1997) p-y criterion.
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