外文翻譯——預(yù)應(yīng)力混凝土建筑-建筑結(jié)構(gòu)-在線瀏覽
2024-07-24 05:26本頁面
【正文】 process used, as well as thorough knowledge of the properties of the particular aggregates and concrete mix to be employed. With posttensioning, anchorages and their bearing plates must be laid out in their physical dimension. It is useful in the preparation of plex anchorage detail layouts to use fullscale drawings, so as to better appreciate the congestion of mild steel and anchorages at the end of the member. Tendons and reinforcing bars should be shown in full size rather than as dotted lines. This will permit consideration to be given as to how the concrete can be placed and consolidated. The end zone of both pretensioned and posttensioned concrete members subject to high transverse or bursting stresses. These stresses are also influenced by minor concrete details, such as chamfers. Provision of a grid of small bars (sometimes heavy wire mesh is used), as close to the end of a girder as possible, will help to confine and distribute the concentrated forces. Closely spaced stirrups and/or tightly spaced spiral are usually needed at the end of heavily stressed members. Recent tests have confirmed that closeness of spacing is much more effective than increase in the size of bars. Numerous small bars, closely spaced, are thus the best solution. Additional mildsteel stirrups may also be required at holddown points to resist the shear. This is also true wherever posttensioned tendons make sharp bends. Practical consideration of concretion dictates the spacing of tendons and ducts. The general rules are that the clear spacing small be oneandonehalf times the maximum size of coarse aggregate. In the overall section, provision must be made for the vibrator stinger. Thus prestressing tendons must either be spaced apart in the horizontal plane, or, in special cases, bundled. In the vertical plane close contact between tendons is quite mon. With postt
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