STUDY OF REPAIRED SPUN PILE TO PILE CAP CONNECTIONS CONTAINING FRACTURED REINFORCEMENTS USING FRP

There is a need for a study on the seismic performance of foundations to facilitate the implementation of performance-based design for bottom structures in Indonesia. To address this need, two series of experimental studies were conducted specifically on spun pile-to-pile cap connections, which are commonly used in Indonesia. The objective of the study was to analyze the performance of these connections and their post-repair behavior. Two specimens were tested: one with an empty pile (SPPC01) and another with a concrete-filled pile (SPPC03). Despite the limited confinement of the piles, both specimens exhibited ductile behavior, achieving displacement ductility within the range of 3.0 to 6.0. The test found that the connections were capable of developing the inelastic stage of the prestressed bars. Both specimens experienced irreparable damage due to fractures in the bars. They were repaired using Fiber Reinforced Polymer (FRP) and retested. The specimens showed some differences in their behavior. SPPC01R exhibited rocking with uplift because the connection was merely embedded, while SPPC03R, which had sufficient embedment, experienced FRP fracture. Although the stiffness of the connections could not be fully restored, the repaired specimens demonstrated a strength recovery of 71% and 86% compared to the original specimens and were able to reach 87% of the design strength. Additionally, they exhibited ductile behavior with ductility ranging from 3.43 to 6.9. To conclude, the typical spun pile connections in Indonesia show ductile behavior. For optimal repairability, it is advised to fill the pile with reinforced concrete, particularly in the connection area.