| 摘要 |
A method for introducing a prestress into a concrete member includes the steps of passing a steel rod (2) through a hollow steel rod (1), applying a tensile force to the hollow steel rod (1), while using the steel rod (2) as a reaction support member, placing concrete (4) around the hollow prestressed steel rod (1), and hardening the concrete (4). The apparatus includes a flat bearing support plate that abuts the concrete to be prestressed, a jack and ram, a rigid support member for interconnecting the jack and ram to the bearing support plate, and a holding cylinder positioned between the bearing support plate and the jack and ram. The bearing support plate and a leading end of the holding cylinder are apertured and screw threadedly receive the threaded trailing end of a hollow steel rod. The trailing end of the steel rod is screw threadedly received by the trailing end of the holding cylinder. When the ram retracts, the hollow steel rod is tensioned between the bearing support plate and the leading end of the holding cylinder.
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