Statnamic Load Testing of Large Diameter Piles at Rigolets Pass Bridge Replacement Project

Abstract

Statnamic load testing was performed on three 66 inch (1,676 mm) diameter, post tensioned, spun cast, concrete cylinder piles and one 30 inch (762 mm) square pre-stressed concrete pile as part of a construction phase load test program for the replacement of the US 90 over Rigolets Pass Bridge near Slidell, Louisiana. The test program also included dynamic testing on all piles and static load testing of the 30 inch (762 mm) pre-stressed concrete piling. Statnamic loads approaching 6,000 kips (27 MN) were utilized on the cylinder piles to fully mobilize side shear in these predominantly friction piles. The static load test and Statnamic load test results on the same 30 inch (762 mm) square pile showed excellent agreement in both load and displacement up to the point of the limiting applied static load. The signal match on this pile showed greater displacement at similar loads. The Statnamic tests of the cylinder piles showed ultimate static capacities of 2,966 kips (13.3 MN), 3,077 kips (13.7 MN) and 3,315 kips (14.7 MN). While the CAPWAP analysis of re-strikes on these piles showed ultimate static capacities of 1,245kips (5.5 MN), 2,030 kips (9.0 MN), and 2,116 kips (9.4 MN). These results suggest that the Statnamic test method was able to fully mobilize the pile side shear resistance, while the dynamic test results were subject to the available hammer energy which was not sufficient to fully mobilize the ultimate static capacities.