Validity of Dynamic Load Test (DLT) on H-piles

The author evaluated H-pile load test data from three (3) sources: 1) Florida database of 641 H-piles from public bridges with Dynamic Load Test (DLT), 2) FHWA database of 23 H-piles having both DLT and Static Load Test (SLT), and 3) a private sector project with detailed DLT and SLT results. The need for this study originated from occasional very large divergence between DLT results and static analyses results of H-piles in several projects. Upon detailed evaluations it is concluded that the observed large divergence is not due to correlations discrepancy, but rather the invalidity of the DLT results for certain H-piles, especially for 1) long H-piles with penetration depth exceeding 30 m, the piles may behave as plugged in the static condition, but as unplugged during dynamic loading event; 2) short H-piles, the conventional lumped CASE damping factor in conventional range should not be relied on for these piles