| 摘要 |
PURPOSE:To raise the retained horizontal durability and axial pressure-durabilty of a pile by a method in which a prestress is introduced into the internal concrete of a steel tube and then removed as drying contraction and creeping phenomenon proceed in the concrete. CONSTITUTION:Many spiral projected lines 2 of slow slopes are formed on the inner surface of a steel tube 1 as an outer shell and on the upper and lower ends of a pile (a), an upper end plate 3 and a coupler end plate 4 are integrally connected to the tube 1. A tension is operated by using the formwork housing the tube 1 as a reactor to produce a desired tensile stress in the tube 1. Even when hair cracks develop, no extension of the cracks occurs by the restricting force of the projected lines 2, the tensile resistance of the concrete (b) is worked, and the retained horizontal durability of the pile (a) is increased. The pile (a) can withstand increased axial pressure and great bending moment to be encountered during the earthquake. |
