Abstract
In order to improve construction productibity of bored cast-in-place concrete piles for structures such as railway viaducts, which have narrow construction space or small overhead clearance, the authors have developed deployable reinforcement pile cage system. In the cage, PC steel strands are used as longitudinal reinforcement. Special devices, which are able to make the PC strands rotate 90 degrees to form the cage, are arranged at the intersections of the longitudinal reinforcement and the spiral reinforcement. With those devices, the cylindrical cage can be deformed into helical shape by twisting and easily deployed by twisting in the opposite direction. As a result, the construction time of the cage can be reduced, especially when the overhead clearance is small. The characteristics of the cage with the consideration of the deformed shape and stiffness of PC strands are presented in this paper.
