Shear Strengthening of RC members

RC 构件的抗剪加固

基本信息

批准号：
12650458
负责人：
MUTSUYOSHI Hiroshi
金额：
$ 2.3万
依托单位：
SAITAMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

To investigate shear behavior of RC beams strengthened with externally bonded FRP sheets, nine RC beams strengthened using CFRP and AFRP sheets for shear upgrading were tested. This study was focused on effective utilization of FRP sheets to prevent debonding of sheets. All RC beams have the same cross section, flexural reinforcements and a clear span of 2800 mm. Since all the beams were designed to fail in shear before yielding of longitudinal reinforcements, stirrups were not provided. Four beams were strengthened using CFRP sheets, while the other four beams were upgraded using AFRP sheets. FRP sheets used were unidirectional, where principal fibers were kept perpendicular to the longitudinal axis of the beam. Different wrapping methods were used to avoid debonding between FRP sheet and concrete such that FRP sheets are anchored with certain length on the top surface of beams. The main experimental variables are the anchorage length of FRP sheets. Design methodologies proposed by different researchers, to calculate FRP sheet contribution to shear capacity (V_f), is also discussed and compared with experimental results.From the results of experiments, the following conclusions are made.1)Effectiveness of externally bonded CFRP and AFRP sheets for enhancement of shear strength of RC beams was confirmed. Maximum 123 % increase for CFRP and 118 % increase for AFRP in shear capacity were observed as compare to that of the control beam.2)It is confirmed that FRP with bonded anchorage is much more effective than U-wrap scheme, and that provision of bonded anchorage of sheet is an effective way to prevent sheet debonding instead of full wrapping of sheet.3)Bonded anchorage of sheet at the top surface of beam resulted in a decrease of interface bond stress.4)Provision of bonded anchorage length showed an increase of more than 100 % in effective strain of FRP sheet at failure, as compare to U-wrap beams.

为了研究用外部键合FRP板增强的RC梁的剪切行为，测试了使用CFRP和AFRP板增强的9个RC梁进行剪切升级。这项研究的重点是有效利用FRP板以防止纸张进行剥离。所有RC梁都具有相同的横截面，弯曲的增援和2800毫米的清晰跨度。由于所有梁的设计都被设计为在纵向增强剂之前的剪切失败，因此未提供马rup。使用CFRP板增强了四个光束，而其他四个梁则使用AFRP板升级。使用的FRP板是单向的，其中主纤维垂直于光束的纵轴。使用不同的包装方法来避免在FRP板和混凝土之间进行脱键，以便将FRP纸锚定在梁的顶部表面上。主要的实验变量是FRP板的锚定长度。还讨论了不同研究人员提出的设计方法，以计算剪切能力（V_F）的贡献，并将其与实验结果进行了比较。从实验的结果，得出以下结论。1）外部粘结的CFRP和AFRP板的有效性，以增强RC光束的剪切强度。观察到与对照光束相比，CFRP最大增加了123％，AFRP的剪切能力增加了118％。2）证实，具有粘合锚固的FRP比U-框方案更有效，并且提供粘结式锚定的贴纸锚固的提供方法可以有效地防止纸张固定的纸张固定。与U型束相比，在失败时有效应变的FRP板有效应变中，粘结锚固长度的增加超过100％。