Testing Layout > Piles and Pile Cap
The previously driven piles are made of ASTM A252 Grade 3 (i.e., 45 ksi minimum yield strength) steel pipe, with an outside diameter and wall thickness of 12.75 and 0.375 in, respectively. The piles were driven closed ended to a depth of approximately 0.5 in below the ground surface. After the removal of three (the middle row) of the original nine piles the remaining piles were spaced 12-ft center to center in the direction of loading. The tops of the piles were cut-off, leaving an approximate embedment of 6 in into the future cap. The piles were filled with 6000-psi concrete and attached to the cap with a rebar cage consisting of six #8 vertical bars and a #4 spiral at a 6-in pitch. The 18-ft long cages extend approximately 5 ft into the cap and support the upper mat of horizontal reinforcement. Inclinometer tubes and shape array tubes were placed in the center north and center south piles. The final cap dimensions are 15-ft long, 11-ft wide and 5.5-ft tall. The concrete used in the cap has a compressive strength of 6000 psi. The cap is reinforced primarily with a mat of transverse and longitudinal reinforcing bars placed in both the top and the bottom of the cap. Each mat consists of #6 bars placed at 8 in on center, each way. Threaded bars to be used as connectors for the shaker and actuators were set into place during construction so as to be integral with the cap.