Investigation on The Restraining Method of Crack Propagation of Precast RC Members By Pretensioning Reinforcing Bars as PC Tendons

以预应力钢筋为预应力筋抑制预制RC构件裂纹扩展方法研究

• 批准号: 01550377
• 负责人: IDEMITSU Takashi
• 金额: $ 1.28万
• 依托单位: Kyushu Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1989
• 资助国家: 日本
• 起止时间: 1989 至 1990
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01550377/
• 关键词: Partially prestressed concrete; Reinforcing bar; Crack restraint; Precast member; Transfer bond; 伝達長; ひびわれ; プレキャストコンクリ-ト; プレストレス; Partially prestressed concrete; Reinforcing bar; Crack restraint; Precast member; Transfer bond; 伝達長; ひびわれ; プレキャストコンクリ-ト; プレストレス

When a precast RC member is fabricated in a factory, the cracks due to the impact load during transportation and the shrinkage of concrete occur very often. The authors tried to prevent the occurrence of these cracks by prestressing the reinforcing bars like PC tendons. From the results of some basic experiments, it has been made clear that by applying prestressing force in bars, not only the less cracking RC members but also the partially prestressed PC members can be obtained.Further experiments were carried out and the following results were obtained :(1)The partially prestressed PC members can be got by prestressing the bars up to a value larger than 60% of the yield point when SD30 is used(2)Only about 30% of initial prestressing force remains in the bars after a few years, but it can considerably restrain the development of the crack width.(3)The mechanism of transfer bond between reinforcing bars used as prestressing tendons and concrete at the end parts of precast members has been made clear and it's also confirmed that the prestressed bars can be anchored at the end parts, even the compressive strength is lower than 200 kgf/cm^2.

当在工厂制造预制的RC成员时，经常发生由于运输过程中的冲击负荷而引起的裂缝经常发生。作者试图通过在PC肌腱（如PC肌腱）（如PC肌电肌）（例如PC肌腱）来防止发生这些裂缝的发生。从一些基本实验的结果中可以清楚地看出，通过在酒吧中施加预应力，不仅可以获得较少破裂的RC成员，而且可以获得部分预应力的PC成员。进行以下结果，并获得了以下结果，并且可以获得（1）仅在30％的BAR上使用PC的30％（1）在30％的位置上获得了30％的点数（1％），则在30％的位置上占用30％（so）。几年后，最初的预应力保留在酒吧中，但是它可以很大程度上限制裂纹宽度的发展。（3）在预制成员的末端用作预应力肌腱和混凝土的加固条之间转移键的机制已得到明确，并且它也可以在最终的部件上固定在压缩的部分，甚至比200 kg^2 KG^2 KG。