湿热酸雨环境对CFRP-混凝土界面剪切粘结性能影响

易富; 杨纪; 马泽宇; 殷雨时

doi:10.13801/j.cnki.fhclxb.20221107.002

湿热酸雨环境对CFRP-混凝土界面剪切粘结性能影响

doi: 10.13801/j.cnki.fhclxb.20221107.002

易富¹,
杨纪²,
马泽宇¹,
殷雨时^3, ,

1.
辽宁工程技术大学　建筑与交通学院，阜新 123000
2.
辽宁工程技术大学　土木工程学院，阜新 123000
3.
同济大学　土木工程学院，上海 200092

基金项目: 国家自然科学基金(51978501；51774163)

详细信息

通讯作者:
殷雨时，博士，副教授，研究方向为混凝土耐久性和FRP加固理论　E-mail：yinys@alumni.tongji.edu.cn

中图分类号: TB332
计量
- 文章访问数: 313
- HTML全文浏览量: 181
- PDF下载量: 12
- 被引次数: 0
出版历程
- 收稿日期: 2022-09-20
- 修回日期: 2022-10-14
- 录用日期: 2022-10-30
- 网络出版日期: 2022-11-07
- 刊出日期: 2023-08-15

Effect of hot and humid acid rain environment on shear bond properties of CFRP-concrete interface

YI Fu¹,
YANG Ji²,
MA Zeyu¹,
YIN Yushi^{3
, ,}

1.
School of Architecture and Transportation, Liaoning University of Engineering and Technology, Fuxin 123000, China
2.
School of Civil Engineering, Liaoning University of Engineering and Technology, Fuxin 123000, China
3.
School of Civil Engineering, Tongji University, Shanghai 200092, China

Funds: National Natural Science Foundation of China (51978501; 51774163)

摘要

摘要: 为研究湿热酸雨环境对碳纤维增强树脂复合材料(CFRP)-混凝土界面剪切粘结性能影响，设计并制作了45个CFRP-混凝土单剪试件，采用机械高温干湿循环和人工配制pH为1.5的酸雨溶液来模拟湿热酸雨环境，通过开展CFRP-混凝土切向剪切试验，分析了混凝土强度和腐蚀次数对界面破坏模式、剥离承载力、极限位移、荷载-位移曲线和粘结区间应变分布的影响，建立了基于湿热酸雨影响系数的界面本构关系模型，并提出了湿热酸雨环境腐蚀程度划分参考方法。研究结果表明：随着混凝土强度提高，界面粘结性能增强，界面剥离位置逐步向胶层处变化；随着腐蚀次数增长，界面粘结性能呈现先升高后降低的变化趋势，3种强度混凝土对应界面剥离荷载和极限位移分别比未受到腐蚀的试件提升3.04%、3.50%、5.78%和0.50%、0.49%、0.95%，酸雨中SO₄ ²⁻离子侵入混凝土表层生成膨胀性物质CaSO₄·2H₂O，会导致腐蚀前期界面粘结性能暂时增强；切向剪切试验中荷载-位移曲线呈现上升、震荡、加强和下降4个阶段；粘结区间上应力传递方向为从加载端传递至自由端；文中提出基于湿热酸雨影响系数的界面本构关系模型，与现有试验数据吻合度较好，且精度较高，偏于安全。相关研究成果可为高湿高热酸雨地区CFRP加固工程提供理论支撑和设计指导。
- 湿热酸雨环境 /
- CFRP /
- 混凝土 /
- 界面 /
- 剪切粘结性能 /
- 耐久性
Abstract: In order to study the influence of hot and humid acid rain environment on the shear bond performance of carbon fiber reinforced polymer (CFRP)-concrete interface, 45 CFRP concrete single shear specimens were designed and manufactured. The hot and humid environment was simulated by mechanical high temperature dry and wet cycles and manually configured acid rain solution with pH 1.5. Through CFRP concrete shear tests, the effects of concrete strength and corrosion times on the interface failure mode, peel bearing capacity, ultimate displacement, load displacement curve and strain distribution in the bonding zone were discussed, an interfacial constitutive model based on the influence coefficient of hot and humid acid rain was established, and the reference method for the division of corrosion degree in hot and humid acid rain environment was proposed. The results show that with the increase of concrete strength, the interface bonding performance is enhanced, and the interface peeling position gradually changes to the adhesive layer. With the increase of corrosion times, the interfacial bonding performance presents a trend of increasing first and then decreasing. The corresponding interfacial peel bearing load and ultimate displacement of the three strength concretes are 3.04%, 3.50%, 5.78% and 0.50%, 0.49%, 0.95% higher than those of the uncorroded specimens, respectively. SO₄ ^2– ions in acid rain invade the concrete surface to generate expansive material CaSO₄·2H₂O, which will temporarily enhance the interfacial bonding performance in the early stage of corrosion. In the tangential shear test, the load displacement curve presents four stages: Rising, concussion, strengthening and falling. The direction of stress transfer in the bonding zone is from the loading end to the free end. The interfacial constitutive model of the influence coefficient of hot and humid acid rain proposed in this paper is in good agreement with the existing test data, with high accuracy and safety. The related research results can provide theoretical support and design guidance for CFRP reinforcement project in high humidity and high heat acid rain area.
- hot and humid acid rain environment /
- CFRP /
- concrete /
- interface /
- shear bonding property /
- durability

HTML全文

图 1 混凝土试件尺寸

Figure 1. Size figure of concrete

下载: 全尺寸图片幻灯片

图 2 CFRP粘贴区域图示

x—Horizontal distance from the free end

Figure 2. Bond area position graphic of CFRP

下载: 全尺寸图片幻灯片

图 3 CFRP布上应变片布置图示

Figure 3. Strain gauges position graphic pasted on CFRP

下载: 全尺寸图片幻灯片

图 4 CFRP-混凝土试件升温曲线

Figure 4. Increasement temperature curve of CFRP-concrete specimens

下载: 全尺寸图片幻灯片

图 5 CFRP-混凝土试件酸雨侵蚀模拟环境

Figure 5. Acid rain corrosion environment of CFRP-concrete specimens

下载: 全尺寸图片幻灯片

图 6 CFRP-混凝土切向剪切试验系统

Figure 6. Tangential shear test system of CFRP-concrete specimens

下载: 全尺寸图片幻灯片

图 7 CFRP-混凝土试件破坏模式

Figure 7. Failure modes of CFRP-concrete specimens

下载: 全尺寸图片幻灯片

图 8 不同腐蚀循环次数下CFRP-混凝土试件界面破坏形态

Figure 8. Interfacial failure patterns under different corrosion times of CFRP-concrete specimens

下载: 全尺寸图片幻灯片

图 9 不同腐蚀次数下CFRP-混凝土试件荷载-位移曲线

Figure 9. Load-displacement curves of CFRP-concrete specimen under different corrosion times

下载: 全尺寸图片幻灯片

图 10 不同腐蚀次数下CFRP应变分布

Figure 10. Strain distribution of CFRP under different corrosion time

下载: 全尺寸图片幻灯片

图 11 基于湿热酸雨劣化因子界面参数回归

Figure 11. Regression of interfacial parameters based on humid and hot acid rain deterioration factor

${\tau _{{\rm{max}}}} $—Interfacial bonding strength between FRP and concrete; $\alpha $—Statistical regression coefficient of experimental data; ${\beta _{\rm{L}}} $, ${\beta _{\rm{w}}} $—Interfacial FRP length influence coefficient and width influence coefficient; ${f_{\rm{t}}} $—Tensile strength of concrete; ${P_{\rm{u}}} $—Interfacial peeling bearing capacity; b_f—Width of FRP sheet; E_f—Elastic modulus of FRP sheet; ${\gamma _1} $—Based parameter ${\tau _{\max }} $ deterioration factor of humid hot acid rain; ${s_{{\rm{f}}{\rm{.}}}} $—Based parameter ${s_{{\rm{f}}{\rm{.}}}} $ deterioration factor of humid hot acid rain

下载: 全尺寸图片幻灯片

图 12 参量($ {\tau }_{\text{max}}，{s}_{\text{f.}} $)和($ \alpha ,{\beta _{\text{w}}},{\beta _{\text{L}}},{f_{\text{t}}} $)之间的关系

R²—Correlation coefficient

Figure 12. Relationships between parameters ($ {\tau _{{\text{max}}}} $, $ {{{s}}_{\text{f.}}} $) and ($ \alpha ,{\beta _{\text{w}}},{\beta _{\text{L}}},{f_{\text{t}}} $)

下载: 全尺寸图片幻灯片

表 1 混凝土配合比

Table 1. Mixture ratio of concrete kg/m³

Specimen	Cement	Fine sand	Coarse aggregate	Water	Fly ash	Water reducer	W/C
C30	298	824	1007	167	53	5.27	0.48
C40	335	737	1018	164	53	9.50	0.42
C50	353	725	1044	144	53	7.20	0.35
Note: W/C—Water to cement ratio.

下载: 导出CSV

表 2 材料物理参数指标

Table 2. Material physical parameters

Material		$ {f_{\text{c}}} $/MPa	$ {f_{\text{t}}} $/MPa	$ {E_{\text{f}}} $/MPa	$ {{{t}}_{\text{f}}} $/mm	$ {{{m}}_{\text{f}}} $/(g·m⁻²)
Specimen	C30	35.0	5.3	—	—	—
	C40	46.0	6.4	—	—	—
	C50	57.5	7.4	—	—	—
CFRP	—	—	3400	2.3×10⁵	0.167	300
Epoxy resin	—	—	38	2.4×10³	—	—
Notes: $ {f_{\text{c}}} $—Compressive strength of concrete cube; $ {f_{\text{t}}} $—Tensile strength of concrete, carbon fiber reinforced polymer (CFRP) and epoxy resin, the tensile strength of concrete is not measured in the test, so it is converted by the formula$ {f_{\text{t}}} = \dfrac{{{{\left( {{f_{\text{c}}}} \right)}^{2/3}}}}{2} $; $ {E_{\text{f}}} $—Elastic modulus of fiber cloth and epoxy resin; $ {{{t}}_{\text{f}}} $—Single layer thickness of fiber cloth; $ {{{m}}_{\text{f}}} $—Mass per unit area of fiber cloth.

下载: 导出CSV

表 3 酸雨溶液配制

Table 3. Acid rain solution mixturement 40 L

pH value	98% sulfuric acid content/(g·L⁻¹)	65% nitric acid content/(g·L⁻¹)	Mole ratio H₂SO₄: HNO₃
1.5	63.24	7.12	9:1

下载: 导出CSV

表 4 酸雨侵蚀试验工况

Table 4. Test conditions of acid rain corrosion

Number	Specimen/block	Corrosion cycle time	Corrosive environment
f_i-0	3×3	0	Non corrosive
f_i-10	3×3	10	High temperature and humidity acid rain environment
f_i-20	3×3	20
f_i-30	3×3	30
f_i-40	3×3	40
i=30, 40, 50	Total: 45	–
Notes: In the expression f_i-a, i represents three concrete strength grades, C30, C40 and C50 respectively; a represents the number of corrosion cycles. For example, f₃₀-10 represents the C30 CFRP-concrete specimen subjected to 10 corrosion cycles.

下载: 导出CSV

表 5 CFRP-混凝土切向剪切试验数值

Table 5. Interfacial shear test data between CFRP and concrete

Strength grade	Peel load/kN	Ultimate displacement/mm
C30	6.89	2.02
C40	7.15	2.05
C50	7.78	2.10

下载: 导出CSV

表 6 CFRP-混凝土试件剥离荷载与极限位移

Table 6. Peel load and ultimate displacement of CFRP-concrete specimen

Strength grade	Corrosion time	P_u/kN				S_f/mm
Strength grade	Corrosion time	1	2	3	Average	1	2	3	Average
C30	0	6.89	6.86	6.92	6.89	1.88	1.92	2.26	2.02
	10	6.54	6.99	7.77	7.10	1.95	1.99	2.15	2.03
	20	6.19	6.35	6.45	6.33	1.45	1.62	1.37	1.48
	30	4.03	3.88	4.15	4.02	1.43	1.41	1.45	1.43
	40	4.03	3.89	4.05	3.99	1.25	1.30	1.35	1.30
C40	0	6.95	7.07	7.43	7.15	1.91	2.07	2.17	2.05
	10	6.56	6.72	8.93	7.40	2.43	1.62	2.14	2.06
	20	6.65	6.98	5.66	6.43	0.81	2.24	1.75	1.60
	30	3.09	5.49	—	4.29	1.28	1.70	—	1.49
	40	4.24	4.39	4.32	4.32	—	1.37	1.35	1.36
C50	0	7.05	7.77	8.52	7.78	2.10	2.24	1.97	2.10
	10	8.20	8.45	8.04	8.23	2.10	2.33	1.93	2.12
	20	6.99	7.13	6.55	6.89	1.95	1.80	1.89	1.88
	30	4.99	4.77	4.55	4.77	1.71	1.75	1.88	1.78
	40	4.10	4.70	4.85	4.75	1.60	1.70	1.80	1.70
Notes: "—" in the table indicates that no valid data is collected due to test error, human operation and other reasons; P_u—Peel load; S_f—Ultimate displacement.

下载: 导出CSV

表 7 腐蚀环境对应混凝土表面腐蚀程度

Table 7. Corrosion degree of concrete surface corresponding to corrosion environment

Ⅰ category	Ⅱ category	Ⅲ category	Ⅳ category
Severe corrosion	Harsh corrosion	Moderate corrosion	Slight corrosion

下载: 导出CSV

表 8 本文模型与现有模型精确度比对

Table 8. Accuracy comparison between new and existed models

Data source	Proposed model	Lu^[10]	Neubauer & Rostasy^[33]	Monti et al^[34]
Data source	Test/Predict	Test/Predict	Test/Predict	Test/Predict
Wu et al^[28]	4.29	6.98	13.14	12.27
Takeo et al^[29]	2.23	3.50	5.55	5.68
Tan^[30]	1.82	2.91	4.56	4.52
Ren^[31]	1.66	2.68	3.76	3.78
Ueda et al^[32]	2.67	4.12	6.48	6.47

下载: 导出CSV

参考文献(34)

[1]	HADIGHEH S A, KE F H, KASHI S M. 3D acid diffusion model for FRP-strengthened reinforced concrete structures: Long-term durability prediction[J]. Construction and Building Materials,2020,261:120548. doi: 10.1016/j.conbuildmat.2020.120548
[2]	江胜华, 姚国文, 刘超越, 等. 湿热环境作用下CFRP加固钢筋混凝土梁的抗弯性能[J]. 西南交通大学学报, 2020, 55(1):175-183. doi: 10.3969/j.issn.0258-2724.20170893 JIANG Shenghua, YAO Guowen, LIU Chaoyue. Flexural behavior of reinforced concrete beams strengthened with CFRP under hydrothermal environment[J]. Journal of Southwest Jiaotong University,2020,55(1):175-183(in Chinese). doi: 10.3969/j.issn.0258-2724.20170893
[3]	李登华, 林浩, 崔东霞, 等. 碳纤维复合材料单向板耐候性及湿热老化性能[J]. 材料科学与工程学报, 2018, 36(4):535-540. doi: 10.14136/j.cnki.issn1673-2812.2018.04.004 LI Denghua, LIN Hao, CUI Dongxia, et al. Weathering resistance and damp heat aging performance of carbon fiber composite one-way board[J]. Journal of Materials Science and Engineering,2018,36(4):535-540(in Chinese). doi: 10.14136/j.cnki.issn1673-2812.2018.04.004
[4]	李杉. 环境与荷载共同作用下FRP加固混凝土耐久性[D]. 大连: 大连理工大学, 2009. LI Shan. Durability of concrete strengthened with FRP under environmental and loading conditions[D]. Dalian: Dalian University of Technology, 2009.
[5]	LUAN H Y, FAN Y F, CHEN A, et al. Exploratory experimental study on flexural behavior of CFRP-reinforced concrete beams subjected to acidic loading effect[J]. Advances in Structural Engineering,2018,21(14):2184-2197. doi: 10.1177/1369433218770533
[6]	王苗, 吕桅桅, 王凯, 等. 武汉市酸雨变化特征及影响因子分析[J]. 气象, 2019, 45(2):282-289. doi: 10.7519/j.issn.1000-0526.2019.02.013 WANG Miao, LYU Weiwei, WANG Kai, et al. Analysis on change characteristics and influencing factors of acid rain in Wuhan[J]. Meteorology,2019,45(2):282-289(in Chinese). doi: 10.7519/j.issn.1000-0526.2019.02.013
[7]	廖洁. 武汉市酸雨地区分布规律的研究[D]. 武汉: 武汉理工大学, 2004. LIAO Jie. Study on the distribution law of acid rain in Wuhan[D]. Wuhan: Wuhan University of Technology, 2004(in Chinese).
[8]	张新民, 柴发合, 王淑兰, 等. 中国酸雨研究现状[J]. 环境科学研究, 2010, 23(5):527-532. ZHANG Xinmin, CHAI Fahe, WANG Shulan, et al. Research progress of acid precipitation in China[J]. Research of Environmental Science,2010,23(5):527-532(in Chinese).
[9]	MAHDIKHANI M, BAMSHAD O, SHIRVANI M. Mechani-cal properties and durability of concrete specimens containing nano silica in sulfuric acid rain condition[J]. Construction and Building Materials,2018,167:929-935. doi: 10.1016/j.conbuildmat.2018.01.137
[10]	陆新征. FRP-混凝土界面行为研究[D]. 北京: 清华大学, 2004. LU Xinzheng. Study on FRP concrete interface behavior[D]. Beijing: Tsinghua University, 2004(in Chinese).
[11]	邹今航, 叶斌, 陈永贵. 湿热环境下碳纤维增强复合材料加固钢筋混凝土梁的耐久性试验[J]. 科学技术与工程, 2020, 20(33):13839-13846. doi: 10.3969/j.issn.1671-1815.2020.33.046 ZOU Jinhang, YE Bin, CHEN Yonggui. Durability performance experiment of reinforced concrete beams strengthened with carbon fiber reinforced ploymer under wet-thermal environments[J]. Science Technology and Engineering,2020,20(33):13839-13846(in Chinese). doi: 10.3969/j.issn.1671-1815.2020.33.046
[12]	余建伟, 杨勇新, 贾彬, 等. 湿热环境下碳纤维增强复合材料的耐久性试验研究[J]. 工业建筑, 2017, 47(8):175-178, 193. doi: 10.13204/j.gyjz201708032 YU Jianwei, YANG Yongxin, JIA Bin, et al. Durability test of carbon fiber reinforced composites in hot and humid environments[J]. Industrial Construction,2017,47(8):175-178, 193(in Chinese). doi: 10.13204/j.gyjz201708032
[13]	薛维培, 刘晓媛, 姚直书, 等. 不同损伤源对玄武岩纤维增强混凝土孔隙结构变化特征的影响[J]. 复合材料学报, 2020, 37(9):2285-2293. doi: 10.13801/j.cnki.fhclxb.20200219.001 XUE Weipei, LIU Xiaoyuan, YAO Zhishu, et al. Effects of different damage sources on pore structure change characteristics of basalt fiber reinforced concrete[J]. Acta Materiae Compositae Sinica,2020,37(9):2285-2293(in Chinese). doi: 10.13801/j.cnki.fhclxb.20200219.001
[14]	XUE W P, LIU X Y, JING W, et al. Experimental study and mechanism analysis of permeability sensitivity of mechanically damaged concrete to confining pressure[J]. Cement and Concrete Research,2020,134:106073. doi: 10.1016/j.cemconres.2020.106073
[15]	罗毅, 张翔, 郭馨艳. 湿热环境下预应力CFRP加固RC梁疲劳性能数值分析[J]. 华南理工大学学报(自然科学版), 2021, 49(10):70-77. LUO Yi, ZHANG Xiang, GUO Xinyan. Numerical analysis of fatigue performance of prestressed CFRP reinforced RC beams in hydrothermal environment[J]. Journal of South China University of Technology (Natural Science Edition),2021,49(10):70-77(in Chinese).
[16]	万先虎. 高温干湿交替环境下FRP-混凝土界面黏结性能的耐久性研究[D]. 哈尔滨: 哈尔滨工业大学, 2013. WAN Xianhu. Study on durability of FRP concrete interface bonding performance under high-temperature dry wet alternate environment[D]. Harbin: Harbin University of Technology, 2013(in Chinese).
[17]	DU J, QU M, ZHANG Y, et al. Simulated sulfuric and nitric acid rain inhibits leaf breakdown in streams: A microcosm study with artificial reconstituted fresh water[J]. Ecotoxi-cology and Environmental Safety,2020,196:110535. doi: 10.1016/j.ecoenv.2020.110535
[18]	LU C F, WANG W, ZHOU Q S, et al. Mechanical behavior degradation of recycled aggregate concrete after simulated acid rain spraying[J]. Journal of Cleaner Production,2020,262:121237. doi: 10.1016/j.jclepro.2020.121237
[19]	周昌林, 朱哲明, 朱爱军. 酸雨腐蚀对混凝土材料断裂特性的影响[J]. 工程科学与技术, 2019, 51(1):144-151. ZHOU Changlin, ZHU Zheming, ZHU Aijun. Effect of acid rain corrosion on fracture properties of concrete materials[J]. Engineering Science and Technology,2019,51(1):144-151(in Chinese).
[20]	SUI L L, LUO M S, YU K Q, et al. Effect of engineered cementitious composite on the bond behavior between fiber reinforced polymer and concrete[J]. Composite Structures,2018,184:775-788. doi: 10.1016/j.compstruct.2017.10.050
[21]	WU Z S, KIM Y J, DIAB H, et al. Recent developments in long-term performance of FRP composites and FRP-concrete interface[J]. Advances in Structural Engineering,2010,13(2):891-903.
[22]	曹琛, 郑山锁, 胡卫兵. 酸雨环境下混凝土结构性能研究综述[J]. 材料导报, 2019, 33(11):1869-1874. doi: 10.11896/cldb.17110051 CAO Chen, ZHENG Shansuo, HU Weibing. Summary of research on concrete structure performance under acid rain environment[J]. Materials Reports,2019,33(11):1869-1874(in Chinese). doi: 10.11896/cldb.17110051
[23]	PAN Z Y, WANG S, LIU Y C, et al. The hydration pore structure and strength of cement-based material prepared with waste soaking solution from acetic acid treatment of rege-nerated aggregates[J]. Journal of Cleaner Production,2019,235:866-874. doi: 10.1016/j.jclepro.2019.06.335
[24]	RAGOUG R, METALSSI O O, BARBERON F, et al. Durabi-lity of cement pastes exposed to external sulfate attack and leaching: Physical and chemical aspects[J]. Cement and Concrete Research,2019,116:134-145. doi: 10.1016/j.cemconres.2018.11.006
[25]	朵润民. 冻融循环和湿热环境下CFRP-高强混凝土粘贴界面耐久性研究[D]. 大连: 大连理工大学, 2015. DUO Runmin. Study on durability of CFRP high-strength concrete bonding interface under freeze-thaw cycles and humid and hot environments[D]. Dalian: Dalian University of Technology, 2015(in Chinese).
[26]	陈梦成, 罗晶, 许开成. 江西省酸雨特征分析及预测模型[J]. 环境科学与技术, 2014, 37(10):167-170. CHEN Mengcheng, LUO Jing, XU Kaicheng. Characteristic analysis and prediction model of acid rain in Jiangxi province[J]. Environmental Science and Technology,2014,37(10):167-170(in Chinese).
[27]	方五军, 李伟文, 曹文昭. 深圳地区混凝土结构耐久性评定及影响因素分析[J]. 工业建筑, 2020, 50(6):117-122. doi: 10.13204/j.gyjz202006019 FANG Wujun, LI Weiwen, CAO Wenzhao. Durability assessment and influence factor analysis of concrete structures in Shenzhen[J]. Industrial Building,2020,50(6):117-122(in Chinese). doi: 10.13204/j.gyjz202006019
[28]	WU Z S, ISLAM S M, SAID H. A three-parameter bond strength model for FRP-concrete interface[J]. Journal of Reinforced Plastic and Composite, 2009, 28(19): 2309-2323.
[29]	TAKEO K, MATSUSHITA H, MAKIZUMI T, et al. Bond characteristics of CFRP sheets in the CFRP bonding technique[J]. Japan Concrete Institution, 1997, 1(1): 1599-1604.
[30]	谭壮. GFRP布加固混凝土梁受力性能的试验研究[D]. 北京: 清华大学, 2022. TAN Zhuang. Experimental research for RC beam strengthened with GFRP[D]. China: Tsinghua University, 2002(in Chinese).
[31]	王文炜. 纤维复合材料加固钢筋混凝土梁抗弯性能研究[D]. 大连: 大连理工大学, 2003. WANG Wenwei. Research on flexural performance of reinforced concrete beams strengthened with fiber composite materials[D]. Dalian: Dalian University of Technology, 2003(in Chinese).
[32]	UEDA T, SATO Y, ASANO Y. Experimental study on bond strength of continuous carbon fiber sheet[J]. ACI, 1999, 63(3): 407-416.
[33]	NEUBAUER U, ROSTASY F S. Design aspects of concrete structures strengthened with externally bonded CFRP plates[J]. ECS Public,1999,2(1):109-118.
[34]	MONTI M, RENZELLI M, LUCIANI P. FRP adhesion in uncracked and cracked concrete zones[J]. International Symposium on FRP Reinforcement for Concrete Structures,2003,6(1):183-192.