Abstract
In this paper, we aim to clarify the bond behavior between EC (Epoxy Coated) strands and cement grout through the experiments, and propose the estimation method for the tension force (P)-displacement (⊿) relationship. EC strands are rust proofing PC strands coated with epoxy resin. This paper represents the pulsating pullout tests of EC strands with cement grout encased in PC beam. The 4 parameters are established; the number of EC strands arranged in steel sheath, the compressive strength of cement grout, the initial prestressing tension of EC strands, and with or without steel sheath. Pulsating pullout tests of PC deformed bar and PC strands are also carried out in order to compare with EC strands. The following conclusions were drawn from the study. 1) The bond strength of EC strands is smaller than that of PC deformed bar. The bond stress is almost constant throughout the transmission surface. During unloading, the bond stress near the end of beam is produced in opposite direction indicating same magnitude under loading. 2) The bond surface of EC strands in the case the 3, 5, 10 strands arranged in steel sheath is evaluated multiplying a bond surface of 1 strand by the number of strands. 3) The compressive strength of cement grout, the epoxy resin coating, the initial prestressing tension and the steel sheath have little influence on bond behavior between PC strands and cement grout. 4) The P-⊿ relationship could be estimated with proposed method.
