Residual Loads Measurements in Driven Steel H-Piles-Paper

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The study examines residual loads in two instrumented steel H-piles driven at a site in northeastern Mississippi. Both piles underwent cyclic compression testing, and one was subsequently tested in tension. Strain gauges and extensometers measured pile loads and movement. Researchers calculated load-transfer curves using three reference conditions: including residual loads from driving and testing, excluding driving-related residual loads, and excluding all residual loads.<br /><br />Residual loads caused by driving were substantial—320 kN in one pile and 258 kN in the other—and strongly affected the magnitude and shape of the measured load-transfer curves. Their distribution along the pile shaft was approximately triangular. When residual loads were excluded, compression load-transfer curves were smoother and generally trapezoidal. Residual loads resulting from load cycles were comparatively insignificant.<br /><br />The tension-test results for the first pile were distorted by residual loads and soil disturbance from its preceding compression test. The findings therefore caution against determining a pile’s pullout capacity using a pile previously loaded in compression. The study also emphasizes careful selection and monitoring of instrumentation, particularly because damaged strain gauges and uncertainty in jack load measurements affected the results. It recommends close monitoring when driving steel H-piles into dense sand or rock, where toe damage may occur.

Keywords

residual loads

steel H-piles

load-transfer curves

cyclic compression testing

tension test

pile driving

strain gauges

extensometers

pullout capacity

dense sand or rock