The Evaluation of Displacement Ductility of Low Confinement Spun Pile to Pile Cap Connections

. Experimental study was carried out on three low confinement spun piles to pile cap connections. The detail followed the typically fixed connection in Indonesia. Reinforced concrete was filled to the spun pile to strengthen the connection region, except SPPC01. Different concrete types were used, shrinkage and non-shrinkage for SPPC02 and SPPC03, respectively. SPPC02 and SPPC03 could reach the targeted drift of 3.5% whereas SPPC01 was stopped at a drift of 2.75%. There was no shear failure detected during the test. The connection behaved as a fixed connection indicated by the fracture failure of the prestressed bars near the connection region. Analysis of the test results focused on displacement ductility. Two definitions of yield and ultimate displacement were employed to seek the possible ductility values. It varied from 3.05 to 6.04 for SPPC01 and from 3.01 to 4.95 for SPPC02 and SPPC03. The non-shrinkage concrete did not affect the strength of the connection but slightly improved the post-peak behavior. The ductility is 6 – 12% higher than spun piles with ordinary concrete. According to the limited ductility referring to ATC 96, JRA 2002, and AASHTO 2011, all specimens could achieve target ductility 3. Hence, it can be concluded that the low confinement spun pile connections performed well in displacement ductility.