• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Monotonic and fatigue flexural behaviour of RC beams strengthened with prestressed NSM CFRP rods.
【24h】

Monotonic and fatigue flexural behaviour of RC beams strengthened with prestressed NSM CFRP rods.

机译：预应力NSM CFRP杆增强了RC梁的单调和疲劳挠曲性能。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The use of near surface mounted (NSM) carbon fibre reinforced polymer (CFRP) reinforcement is a recent and a promising technique for increasing the flexural capacity and the fatigue life of reinforced concrete (RC) flexural members. Prestressing the NSM CFRP rod may be utilized for a further enhancement in the monotonic and fatigue flexural response of RC beams.;The test results showed that strengthening the RC beams with NSM CFRP rods increased both the monotonic flexural capacity and the fatigue strength. An increase in the yield and ultimate load of 26% and 50% was achieved, when the beams were strengthened with non-prestressed CFRP rod compared to the control beam. Also, the flexural stiffness of the strengthened beam was slightly enhanced by 16% over that of the control beam. When the beams were strengthened with prestressed CFRP rod (40% and 60%), considerable improvements in the cracking, yield, and ultimate loads were achieved as well as the flexural stiffness (serviceability). In a comparison to the control beam, an increase up to 91% in the yield load and 79% in the ultimate load were obtained, in addition to 52.6% improvement in the flexural stiffness (pre-yielding) when a prestressed NSM CFRP rod was applied.;A model to predict the flexural behaviour of the beams (control, non-prestressed, 40%, and 60% prestressed strengthened beams) under monotonic loading using section analysis is presented. It includes a model for flexural crack spacing considering the effect of the CFRP reinforcement, and the transfer length model. For an easy use, the monotonic flexural behaviour model is adopted in a computer language (Visual Basic 6).;A model based on strain-life approach is also utilized to predict the fatigue life of the beams at various load ranges for all tested RC beams. For a given load range, by obtaining the nominal maximum and minimum stresses using the monotonic flexural model, the fatigue life of a beam is estimated by accounting for the effect of notch (ribs of the reinforcing bars), and the effect of mean stress.;The aim of this study is to investigate the effectiveness of strengthening RC beams with nonprestressed and prestressed CFRP rods to increase the monotonic and fatigue flexural strength of the beams. Twenty-two RC beams were fabricated. Five beams were not strengthened and acted as control to simulate an existing structural member. The other beams were divided into groups that were strengthened with non-prestressed CFRP rod (0% prestressed), and prestressed CFRP rod (40%, or 60% prestressed of the CFRP rod tensile strength). A beam from each group was tested under monotonic load and acted as a reference beam for those tested under cyclic loads.;In summary, this study presents the first North American experience by using prestressed NSM CFRP rod for strengthening RC beams. Using such high prestressing levels of 40% and 60% with NSM strengthening method is considered the original contribution for monotonic flexural behaviour. Under cyclic loading, investigating the fatigue behaviour and constructing the fatigue life curves for RC beams strengthened with non-prestressed NSM CFRP rod is a considerable contribution to the very limited information available in the literature. This study also includes the inventiveness of testing the fatigue response of the RC beams strengthened with prestressed NSM CFRP rod. A monotonic flexural model of strengthened RC beams with non-prestressed and prestressed NSM CFRP strengthened beams was developed to predict load versus deflection, strain in the concrete, strain in the tension and compression steel reinforcement, and strain in CFRP rod. The model is verified with the experimental results with excellent agreement. A model using strain-life approach was also developed to predict the fatigue life of non-prestressed and prestressed beams with a reasonable accuracy.
机译：近表面安装（NSM）碳纤维增强聚合物（CFRP）增强的使用是增加钢筋混凝土（RC）挠曲构件的挠曲能力和疲劳寿命的最新且很有前途的技术。预应力NSM CFRP杆可进一步增强RC梁的单调和疲劳挠曲响应。试验结果表明，使用NSM CFRP杆加固RC梁可提高单调抗弯能力和疲劳强度。当使用非预应力CFRP杆加固梁时，与控制梁相比，梁的屈服强度和极限载荷提高了26％和50％。同样，与控制梁相比，加固梁的抗弯刚度稍微提高了16％。当用预应力CFRP杆（40％和60％）加固梁时，在开裂，屈服和极限载荷以及抗弯刚度（可维修性）方面取得了显着改善。与控制梁相比，在使用预应力NSM CFRP杆时，抗弯刚度（预屈服）提高了52.6％，屈服载荷提高了91％，极限载荷提高了79％。提出了一种使用截面分析来预测单调荷载下梁（控制梁，非预应力梁，40％和60％预应力梁）的弯曲行为的模型。它包括考虑了CFRP加固效果的挠曲裂缝间距模型和传递长度模型。为方便使用，计算机语言（Visual Basic 6）采用了单调弯曲行为模型。;基于应变寿命方法的模型也用于预测所有测试的RC在不同载荷范围下梁的疲劳寿命梁。对于给定的载荷范围，通过使用单调挠曲模型获得名义上的最大和最小应力，可以通过考虑缺口（钢筋的肋骨）的影响和平均应力的影响来估算梁的疲劳寿命。 ；本研究的目的是研究用非预应力和预应力CFRP杆加固RC梁以增加梁的单调和疲劳挠曲强度的有效性。制作了22条RC梁。五个梁没有得到加强，并用作模拟现有结构构件的控制。将其他梁分为两组，分别用非预应力CFRP杆（0％预应力）和预应力CFRP杆（CFRP杆抗张强度的40％或60％）加强。来自各组的梁在单调荷载下进行了测试，并作为循环荷载下的参考梁。总之，本研究通过使用预应力NSM CFRP杆来加固RC梁，展示了北美的首次经验。使用NSM加固方法使用如此高的40％和60％的高预应力水平，被认为是对单调弯曲行为的原始贡献。在循环载荷下，研究疲劳行为并构建用非预应力NSM CFRP杆加固的RC梁的疲劳寿命曲线，对于文献中提供的非常有限的信息有很大贡献。这项研究还包括测试用预应力NSM CFRP杆加固的RC梁的疲劳响应的创造性。建立了带有非预应力和预应力NSM CFRP增强梁的钢筋混凝土梁的单调挠性模型，以预测载荷与挠度，混凝土中的应变，拉伸和压缩钢筋中的应变以及CFRP杆中的应变。模型与实验结果吻合良好。还开发了使用应变寿命方法的模型，以合理的精度预测非预应力和预应力梁的疲劳寿命。

著录项

  • 作者

    Badawi, Moataz Assad.;

  • 作者单位

    University of Waterloo (Canada).;

  • 授予单位 University of Waterloo (Canada).;
  • 学科 Civil engineering.
  • 学位 Ph.D.
  • 年度 2007
  • 页码 277 p.
  • 总页数 277
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号