Test Pile Programs at Chicagoâ€™s Navy Pier-Video

Video Transcription

Video Summary

The presentation compares two pile-testing programs near Chicago’s Navy Pier, conducted 25 years apart. In the 1990s, large steel piles driven into dense silt were tested statically and dynamically. CAPWAP results were close to static capacities, and the modified Gates formula performed reasonably; the Washington State DOT formula substantially overpredicted capacity.<br /><br />A more recent flyover project used smaller piles in soft clay, with no initial testing and uncertain capacity estimates. Dynamic testing and restrikes showed substantial setup, especially near a stiff clay layer. After 30 days, measured capacities reached the project’s required range. A static test and dynamic test at matching tip elevations both indicated about 120 kips.<br /><br />The presenter recommends avoiding dynamic formulas where possible, using wave-equation analysis, varying test-pile depths, and allowing time for restrikes to capture setup. The discussion emphasized that longer restrike intervals may reveal further capacity gains and enable more economical pile designs.

Keywords

pile testing

CAPWAP

dynamic testing

static capacity

pile setup