The Development of the Concrete Piles Reinforced by Strands, under the Condition of Limited Space in Height, and its Application for Practical Construction

摘要

It is required to make the height of construction space as low as possible in the case of reconstructing existing transportation structures (ex. railroad viaducts) with preserving their function to manage traffics. In Japanese cities most viaducts are supported by piles because of ground conditions. In order to construct piles in site with height restrictions, it is necessary to use short "steel-bar baskets" (made of deformed bars) and compose them with mechanical or lap joints, which will raise construction cost and working hour (Fig.1 (a)).To solve this problem, the authors developed a technique for design and construction of reinforced concrete (RC) piles with PC-strands having higher strength and flexibility than those of deformed bars for its axial reinforcements (Fig.1 (b)). Strands are usually used with tensile strain, but in this method strains are used with no tensile strain. In this paper, the concrete piles reinforced with strands are called "SR-pile(s)". Up to now, we have tested the properties of SR-pile, and have estimated its failure mechanism, ultimate strength and stiffness.