| 曲面混凝土构件内弧粘贴FRP弦剥离效应 |
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| 引用本文： | 任伟,郭林,杨旸,张德强.曲面混凝土构件内弧粘贴FRP弦剥离效应[J].交通运输工程学报,2019,19(1):60-70. |
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| 作者姓名： | 任伟 郭林 杨旸 张德强 |
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| 作者单位： | 1.长安大学 旧桥检测与加固技术交通行业重点实验室，陕西 西安 7100642.西安曲江建设集团有限公司，陕西 西安 7100613.哈特福德大学 土木环境与生物医学工程系，康涅狄格 西哈特福德 06117 |
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| 基金项目： | 国家自然科学基金项目51678061陕西省自然科学基础研究计划项目2016JM5043 |
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| 摘 要： | 进行了26个曲面构件的FRP-混凝土界面粘贴试验, 研究了混凝土强度、FRP粘贴层数、FRP粘贴长度与构件曲率对粘贴强度、界面应变与破坏机理的影响。研究结果表明: 曲面混凝土构件内弧粘贴FRP易出现3种破坏形态: 弦剥离破坏、FRP在裂缝处被拉断和FRP在试件裂缝一侧发生剥离, 其中构件曲率越大, 越容易发生弦剥离破坏, 小曲率构件多发生FRP拉断破坏; 随外荷载的增大, FRP应变峰值有一个向后传递的变化过程, 说明沿纤维长度方向的FRP并不是全部参与工作, 存在一个有效工作(粘贴) 长度; 对本试验数据采用虚拟零点方法分析得出, 曲面混凝土构件内弧粘贴FRP有效粘贴长度约为14 cm; 曲率对粘贴强度影响显著, 曲率增大, 纤维应变梯度增大, 有效粘贴长度变小, 粘贴强度降低; 曲率相同时, 纤维层数越多, 沿纤维方向应变分布越均匀, 粘贴强度越大, 但是这一增长并非与FRP层数成线性关系, 2层纤维粘贴强度约为1层的1.5倍; 当纤维层数增加时, 粘贴层法向应力增大较快, 试件更易发生弦剥离破坏, 这种破坏是由法向粘贴应力与面内剪应力的耦合效应引起的; 粘贴层应力函数可用内弧曲率圆心角的余弦函数表示, 当矢高分别为30、60、90 mm时, 构件平均误差分别为7.7%、2.4%与8.8%, 因此, 函数精度较高。
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| 关 键 词： | 桥梁工程 旧桥加固 曲面混凝土构件 内弧粘贴FRP 弦剥离效应 |
| 收稿时间： | 2018-09-11 |
String debonding effect of curved RC member reinforced by bonding FRP in intrados |
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| REN Wei,GUO Lin,YANG Yang,ZHANG De-qiang.String debonding effect of curved RC member reinforced by bonding FRP in intrados[J].Journal of Traffic and Transportation Engineering,2019,19(1):60-70. |
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| Authors: | REN Wei GUO Lin YANG Yang ZHANG De-qiang |
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| Affiliation: | 1.Key Laboratory of Bridge Detection Reinforcement Technology of Ministry of Transport, Chang'an University, Xi'an 710064, Shaanxi, China2.Xi'an Qujiang Construction Group Co., Ltd., Xi'an 710061, Shaanxi, China3.Department of Civil, Environmental, and Biomedical Engineering, University of Hartford, West Hartford 06117, Connecticut, USA |
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| Abstract: | The bonding tests of FRP (fiber reinforced polymer/plastic)-concrete interfaces of 26 curved surface specimens were executed, and the influences of concrete strength, FRP bonding layer numbers, FRP bonding length, and component curvatures on the adhesive strength, interface strain and failure mechanism were investigated. Research result shows that there are three kinds of failure modes in curved concrete members, including the string peeling, FRP fracture at the crack, FRP peeling on the crack side. The greater the curvature of the component, the more likely the string peeling will occur. FRP tensile failure often occurs in small curvature members. With the increase of external load, the peak value of FRP strain has a backward transfer process. It is shown that the FRP along the fiber length is not all involved in the work, and there is an effective working (bonding) length. The analysis result of the test data by the virtual zero point method shows that the effective length of FRP pasted on curved concrete members is about 14 cm. The curvature has a significant effect on the adhesive strength. With the increase of the curvature, the changing gradient of the fiber strain increases, the effective adhesive length becomes shorter, and the adhesive strength decreases. When the curvature is the same, the more the number of fiber layers, the more uniform the strain distribution along the fiber direction and the higher the adhesive strength. But this increase is not linear with the number of FRP layers, and the adhesive strength with two layers of fiber is about 1.5 times of that with one layer. When the number of fiber layers increases, the normal stress of the adhesive layer increases rapidly, and the specimens are more prone to string-debonding failure. This failure is caused by the coupling effect between the normal bonding stress and in-plane shear stress. The stress function of the pasting layer can be expressed by the cosine function of the center angle of internal arc curvature. When the vector height is 30, 60, and 90 mm, the average error of the component is 7.7%, 2.4%, and 8.8%, therefore, the function has higher accuracy. |
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