Abstract:
Two (2) nearby developments supported on drilled displacement piles were recently completed in the Gowanus neighborhood of Brooklyn, New York. Subsurface conditions are similar at both sites and the allowable compressive pile loads for both projects was initially 120 tons. Construction at one site was delayed and started about one year after work at the first site began. During the delay, Ownership decided to increase the building height of the second project. To limit changes to the foundation design, MRCE performed a detailed review of strain gauge instrumented load test data to study increasing the allowable pile loads. Load transfer (t-z) curves were derived for various strata along the pile length. The load transfer curves were then used to simulate compression load tests at the second site. Based on the simulated results, the allowable compressive load was increased to 150 tons which allowed the building height to increase with no change in number or length of piles. Subsequent load testing at the second project compared well with the simulated test results and both projects have been successfully completed. Â Â