Incorporating Load Test Data in Design for a Hospital in Downtown San Francisco-PPT Presentation

PPT Presentation

Pdf Summary

The presentation describes how load-test data informed the foundation design for the 16-story New Hospital Parnassus Heights in San Francisco. The building is up to 294 feet tall, covers approximately 62,000 square feet, and has a full basement and partial sub-basement. Maximum demand on an individual drilled pier is 8,000 kips.<br /><br />Because subsurface conditions vary significantly across the site, the team conducted static and dynamic tests on six drilled piers at four locations: four 24-inch-diameter piers and two 48-inch-diameter piers. Testing aimed to measure side resistance in the Franciscan Complex and overburden materials, and to calibrate dynamic CAPWAP results against static capacity. Static-test data were interpreted using hyperbolic projection and Chin–Kondner extrapolation, with failure defined at a displacement of 4% of pier diameter. Dynamic tests were analyzed by GRL Engineers and extrapolated to estimate fully mobilized resistance.<br /><br />Measured skin friction varied substantially by material, with particularly high values reported in sandstone and greenstone. The team used test results, soil and rock profiles, and target-layer considerations to develop axial-capacity curves for six design areas and recommend capacities for 24-inch piers.<br /><br />Key conclusions were that the site’s spatial variability requires area-specific design, installation must be continuously monitored, and the design should account for anomalous conditions.

Keywords

load-test

foundation design

drilled piers

static tests

dynamic tests

skin friction

axial capacity

Franciscan Complex

CAPWAP

site variability