Experiment on bond performance between CFRP bar and seawater sea sand concrete and its working mechanism
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摘要: 通过碳纤维增强树脂复合材料(CFRP)筋与海水海砂混凝土的中心及偏心拉拔试验,对比了CFRP筋在不同条件下拔出时的粘结应力及滑移值大小,得到完整的CFRP筋/海水海砂混凝土粘结-滑移曲线,同时分析了CFRP筋在混凝土中发生滑移时会产生的若干破坏模式,在此基础上对粘结-滑移曲线不同受力阶段特点进行了分析。同时,采用正交试验的方式,获得了不同因素对CFRP筋/混凝土粘结强度的影响程度。试验表明,CFRP筋/混凝土粘结力中摩擦力的占比较大,且粘结强度最主要的影响因素是混凝土的强度等级。除了传统拉拔试验中会出现的受力筋拉出破坏和混凝土劈裂破坏外,CFRP筋还会由于自身的外形、工艺及力学性能的影响,发生自身破坏。对不同破坏模式、受力筋外形的三种CFRP筋/海水海砂混凝土粘结-滑移曲线,采用多种理论表达式进行对比,最终得到不同条件下CFRP/海水海砂混凝土的粘结-滑移本构关系表达式。Abstract: In order to study the bond performance between carbon fibre reinforced polymer (CFRP) bars and seawater sea sand concrete, the pull-out test of CFRP and seawater sea sand concrete was carried out in different conditions and the bond-slip curve was obtained. During the test, different failure modes were observed and concluded to analyze the failure mechanism between CFRP bars and seawater sea sand concrete. The influence of different factors on the bond performance was analyzed based on orthogonal experiment. The results show that the strength of concrete is the most important factor affecting the bond strength, and the friction plays a large part in the bond stress. Besides the pull-out damage and concrete splitting damage, CFRP damage exists in the test due to the production process and mechanical performance of CFRP itself. Based on the results above, three types of bond-slip constitutive relation expression of CFRP/seawater sea sand concrete were finally concluded by curve fitting and comparing.
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Key words:
- ocean engineering /
- CFRP /
- seawater sea sand /
- failure mode /
- bond mechanism /
- constitutive relation
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表 1 碳纤维增强树脂复合材料(CFRP)/海水海砂混凝土拉拔正交试验设计
Table 1. Carbon fiber reinforced polymer (CFRP)/seawater sea sand concrete orthogonal test design
Group Compressive strength Surface type c/d 1 C30 A 2 2 C40 B 2 3 C50 C 2 4 C50 B 4 5 C40 A 4 6 C30 C 4 7 C30 B 7 8 C40 C 7 9 C50 A 7 Notes:c/d—Thickness of concrete protective layer to the diameter of CFRP bars; A, B, C—Three types of CFRP surface which is single winding, double winding and thread. 表 2 CFRP筋尺寸及力学性能
Table 2. Size and mechanical performance of CFRP bars
CFRP Surface type D/mm E/GPa $ {\sigma }_{\rm{t}} $/MPa A Single winding 10 180.0 1862.3 B Double winding 10 166.4 1670.5 C Thread 10 172.1 1634.0 Avg. — 10 172.8 1722.3 Notes:D—Diameter of the CFRP bars; E—Elasticity modulus; $ {\sigma }_{\rm{t}} $—Tensile strength. 表 3 混凝土配合比
Table 3. Proportions of concrete
Strength Water
binder
ratioSeawater/
kgCoal
ash/
kgCement/
kgSand
ratioSea
sand/
kgCoarse
aggregate/
kgWater
reducer/
kgTotal
mass/
kgCompress
strength/
MPaC30 0.521 184 70.70 282.79 0.396 756.26 1152.7 3.535 2450 37.5 C40 0.422 184 87.27 349.06 0.366 669.00 1156.3 4.363 2450 49.0 C50 0.345 184 106.56 426.24 0.344 593.70 1134.2 5.328 2450 58.9 表 4 CFRP筋/海水海砂混凝土拉拔试验结果
Table 4. Results of CFRP bar/seawater sea sand concrete pull-out test
No. Specimen
numberBond
strength/MPaPeak
displace-
ment/mmDamage
type1 CFRP(A)-SSC50-c/d 7-3 12.22 — a 2 CFRP(A)-SSC50-c/d 7-4 9.02 3.13 a 3 CFRP(A)-SSC50-c/d 7-5 6.76 8.44 c 4 CFRP(B)-SSC50-c/d 4-1 15.27 8.24 a 5 CFRP(B)-SSC50-c/d 4-3 18.31 10.91 a 6 CFRP(B)-SSC50-c/d 4-5 16.15 6.20 b 7 CFRP(C)-SSC50-c/d 2-3 12.51 2.28 a 8 CFRP(C)-SSC50-c/d 2-4 11.00 1.60 c 9 CFRP(C)-SSC50-c/d 2-6 13.76 3.87 c 10 CFRP(A)-SSC40-c/d 4-1 10.40 11.67 a 11 CFRP(A)-SSC40-c/d 4-2 14.82 18.10 a 12 CFRP(A)-SSC40-c/d 4-6 11.92 21.17 a 13 CFRP(B)-SSC40-c/d 2-4 14.03 6.18 b 14 CFRP(B)-SSC40-c/d 2-5 13.00 5.79 b 15 CFRP(B)-SSC40-c/d 2-2 13.71 7.70 b 16 CFRP(C)-SSC40-c/d 7-1 16.88 6.65 a 17 CFRP(C)-SSC40-c/d 7-2 12.72 2.82 a 18 CFRP(C)-SSC40-c/d 7-4 16.71 7.63 a 19 CFRP(A)-SSC30-c/d 2-3 8.26 3.26 b 20 CFRP(A)-SSC30-c/d 2-4 9.02 4.70 b 21 CFRP(A)-SSC30-c/d 2-6 9.67 7.92 a 22 CFRP(B)-SSC30-c/d 7-1 10.85 12.83 a 23 CFRP(B)-SSC30-c/d 7-2 9.21 14.50 a 24 CFRP(B)-SSC30-c/d 7-4 13.43 11.59 a 25 CFRP(C)-SSC30-c/d 4-2 8.82 1.98 c 26 CFRP(C)-SSC30-c/d 4-4 6.95 1.12 c 27 CFRP(C)-SSC30-c/d 4-6 9.42 1.96 c Notes:Specimen number was selected according to the surface type-concrete strength-ratio of protective layer thickness to diameter-specimen number; SSC—Seawater sea sand concrete; a, b, c—Three types of damage mode which is pull-out failure, concrete splitting failure and CFRP failure, respectivly. 表 5 不同因素下CFRP筋/海水海砂混凝土粘结强度值及峰值点位移
Table 5. Bond strengths and displacements at peak point of CFRP bar/seawater sea sand concrete under different factors
Parameter Value Bond strength/
MPaDisplacement/
mmCompressive
strength50 12.78 5.86 40 13.80 9.75 30 9.51 6.65 c/d 7 11.98 8.41 4 12.45 7.52 2 11.66 4.81 Surface type A 10.23 10.55 B 13.77 9.33 C 12.09 3.32 Avg. — 12.03 7.42 表 6 CFRP筋/海水海砂混凝土粘结强度影响因素正交结果方差分析
Table 6. Variance analysis of orthogonal results of influence factors of bond strength of CFRP bar/seawater sea sand concrete
Variation SS df MS F F0.05 F0.01 X 90.15 2 45.07 12.97 3.55 6.01 Y 56.47 2 28.23 8.13 − − Z 2.84 2 1.42 0.41 − − Group 3.26 2 1.63 0.47 3.55 6.01 e1 46.94 2 23.47 6.75 − − e2 55.60 16 3.47 − − − Total 255.25 26 − − − − Notes: X, Y, Z—Three factors of orthogonal test which is concrete strength, ratio of thickness to diameter and CFRP bar surface mode, respectivly; e1, e2—Model error and test error; SS, df —Sum of squares and degrees of freedom of bond strength; MS—Mean square error. 表 7 平方和回归分析法(SSR)中不同CFRP筋/海水海砂混凝土粘结强度影响因素均值及差值
Table 7. Mean and difference under different influence factors of bond strength of CFRP bar/seawater sea sand concrete in sum of squares regression (SSR) method
Parameter Bond strength/MPa Difference 1 Difference 2 X2 13.80 4.28 1.02 X3 12.78 3.26 − X1 9.51 − − Y2 13.77 3.54 1.69 Y3 12.09 1.85 − Y1 10.23 − − Z3 12.45 0.79 0.47 Z2 11.98 0.32 − Z1 11.66 − − 表 8 CFRP筋/海水海砂混凝土拟合结果决定系数R2
Table 8. Determination coefficient R2 of fitting results of CFRP bar/seawater sea sand concrete
Model First type Second type Third type Malvar 0.991957 0.997957 0.994637 BPE 0.972730 0.972740 0.995863 CMR 0.987717 0.986910 0.974247 Continuous curve 0.968770 0.952513 0.882653 Notes: BPE—Bertero-Popov-Eligehausen; CMR—Cosenza-Man-
fredi-Realfonzo.表 9 CFRP筋/海水海砂混凝土拟合参数
Table 9. Fitting parameters of CFRP bar/seawater sea sand concrete
Parameter CFRP(B)-SSC30−c/d 7-4 CFRP(A)-SSC30-c/d 2-4 Parameter CFRP(C)-SSC40-c/d 7-2 F 4.788 4.363 $ a $ 0.72 G −3.083 −2.682 $ \gamma $ 0.93 k −0.168 −1.176 $ \varphi $ 0.07 $ \omega $ 1.33 $ \rho $ −1.17 Notes:F,G,k,$ \varphi $,$ \omega $,$ \gamma $,$ \rho $—Fitting parameters; $ \alpha $—Curve correction factor. -
[1] 冷发光, 丁威, 周永祥, 等. 海砂混凝土应用技术的若干要点[J]. 施工技术, 2011, 40(7):97-100.LENG Faguang, DING Wei, ZHOU Yongxiang, et al. Several key points of application technology of sea sand concrete[J]. Construction Engineering,2011,40(7):97-100(in Chinese). [2] 冯鹏, 王杰, 张枭, 等. FRP与海砂混凝土组合应用的发展与创新[J]. 玻璃钢/复合材料, 2014(12):13-18.FENG Peng, WANG Jie, ZHANG Xiao, et al. Development and innovation of combined application of FRP and sea sand concrete[J]. Composites Science and Engineering,2014(12):13-18(in Chinese). [3] 李田雨, 张玉梅, 刘小艳, 等. 海水海砂高性能海工混凝土力学及早期工作性研究[J]. 混凝土, 2019(11):1-5. doi: 10.3969/j.issn.1002-3550.2019.11.001LI Tianyu, ZHANG Yumei, LIU Xiaoyan, et al. Research on the preparation and durability of brine marine sand high performance concrete[J]. Concrete,2019(11):1-5(in Chinese). doi: 10.3969/j.issn.1002-3550.2019.11.001 [4] 秦斌. 海水海砂混凝土基本力学性能研究[J]. 混凝土, 2019(2):90.QIN Bin. Basic mechanical properties of seawater and sea sand concrete[J]. Concrete,2019(2):90(in Chinese). [5] 梅葵花, 徐进. FRP简介及其在桥梁工程中的应用综述[J]. 中外公路, 2010, 30(4):247-250.MEI Kuihua, XU Jin. Brief introduction of FRP and its application in bridge engineering[J]. Journal of China & Foreign Highway,2010,30(4):247-250(in Chinese). [6] WU Z. Fatigue degradation and life prediction of basalt fiber-reinforced polymer composites after saltwater corrosion[J]. Materials & Design, 2019, 163(5): 107529. [7] 王磊, 李威, 陈爽, 等. 海水浸泡对FRP筋-珊瑚混凝土粘结性能的影响[J]. 复合材料学报, 2018, 35(12):3458-3465.WANG Lei, LI Wei, CHEN Shuang, et al. Effects of seawater soaking on the bonding properties of FRP bars-coral concrete[J]. Acta Materiae Compositae Sinica,2018,35(12):3458-3465(in Chinese). [8] 叶列平, 冯鹏. FRP在工程结构中的应用与发展[J]. 土木工程学报, 2006, 39(3):24-36. doi: 10.3321/j.issn:1000-131X.2006.03.004YE Lieping, FENG Peng. Applications and development of fiber-reinforced polymer in engineering structures[J]. China Civil Engineering Journal,2006,39(3):24-36(in Chinese). doi: 10.3321/j.issn:1000-131X.2006.03.004 [9] 郝庆多, 王言磊, 侯吉林, 等. GFRP带肋筋粘结性能试验研究[J]. 工程力学, 2008(10):158-165.HAO Qingduo, WANG Yanlei, HOU Jilin, et al. Experimental study on bond behavior of GFRP ribbed rebars[J]. Engineering Mechanics,2008(10):158-165(in Chinese). [10] 张海霞, 朱浮声, 孙丽, 等. FRP筋与混凝土粘结滑移试验研究[J]. 沈阳建筑大学学报(自然科学版), 2008(6):989-992.ZHANG Haixia, ZHU Fusheng, SUN Li, et al. Experimental study on bond slip between FRP bars and concrete[J]. Journal of Shenyang Jianzhu University(Natural Science),2008(6):989-992(in Chinese). [11] ROMAN O, ROBERT L Y. Bond strength of fiber reinforced polymer rebars in normal strength concrete[J]. Compo-site Constructions,2005,9(3):203-213. doi: 10.1061/(ASCE)1090-0268(2005)9:3(203) [12] MANJOLA C, YASER J, SAMIR D. Bond performance of deep embedment FRP bars epoxy-bonded into concrete[J]. Engineering Structures,2017,147:448-457. [13] 过镇海. 钢筋混凝土原理[M]. 北京: 清华大学出版社, 2013.GUO Zhenhai. Principles of reinforced concrete[M]. Beijing: Tsinghua University Press, 2013(in Chinese). [14] 中华人民共和国住房和城乡建设. JGJ55—2011 普通混凝土配合比设计规程[S]. 北京: 中国工业建筑出版社, 2011.Ministry of Housing and Urban-Rural Development of the People’s Republic of China. JGJ55—2011 Design specification for mix proportion of ordinary concrete[S]. Beijing: China Architecture & Building Press, 2011(in Chinese). [15] 中华人民共和国住房和城乡建设部. JGJ206—2010 海砂混凝土应用技术规范[S]. 北京: 中国工业建筑出版社, 2010.Ministry of Housing and Urban-Rural Development of the People’s Republic of China. JGJ206—2010 Technical specification for sea sand concrete application[S]. Beijing: China Architecture & Building Press, 2010(in Chinese). [16] 徐金金, 杨树桐, 刘治宁. 碱激发矿粉海水海砂混凝土与CFRP筋粘结性能研究[J]. 工程力学, 2019, 36(S1):175-183.XU Jinjin, YANG Shutong, LIU Zhining. Study on the bond performance between cfrp bars and alkali-activated slag seawater and sea sand concrete[J]. Engineering Mecha-nics,2019,36(S1):175-183(in Chinese). [17] MALVAR L J. Tensile and bond properties of GFRP reinforc-ing bars[J]. ACI Materials Journal,1995,92(3):276-285. [18] ELIGEHAUSEN R, POPOV E P, BERTERO V V. Local bond stress slip relationship of deformed bars under generalized excitations[R]. Berkeley: Earthquake Engineering Research Center, 1983. [19] COSENZA E, MANFREDI G, REALFONZO R. Behavior and modeling of bond of FRP rebars to concrete[J]. Journal of Composites for Construction,1997,1(2):40. doi: 10.1061/(ASCE)1090-0268(1997)1:2(40) [20] 高丹盈, 朱海堂, 谢晶晶. 纤维增强塑料筋混凝土粘结滑移本构模型[J]. 工业建筑, 2003, 33(7):41. doi: 10.3321/j.issn:1000-8993.2003.07.011GAO Danying, ZHU Haitang, XIE Jingjing. The constitutive models for bond slip relation between FRP rebars and concrete[J]. Industrial Construction,2003,33(7):41(in Chinese). doi: 10.3321/j.issn:1000-8993.2003.07.011