纤维网格端锚自锁增强机制

周朝阳; 邓楷; 林国制; 汪毅

doi:10.13801/j.cnki.fhclxb.20231206.003

纤维网格端锚自锁增强机制

doi: 10.13801/j.cnki.fhclxb.20231206.003

周朝阳^{1, 2},
邓楷²,
林国制³,
汪毅^{1, 2, ,}

1.
中南大学　高速铁路建造技术国家工程研究中心，长沙 410075
2.
中南大学　土木工程学院，长沙 410075
3.
中机国际工程设计研究院有限责任公司，长沙 410007

基金项目: 国家自然科学基金项目(52178308)；湖南省自然科学基金项目(2021JJ60026；2022JJ30735)；中南大学创新驱动计划项目(2023CXQD051)

详细信息

通讯作者:
汪毅，博士，特聘教授，博士生导师，研究方向为混凝土结构耐久性　E-mail: wangyi.ce@csu.edu.cn

中图分类号: TU375.1；TB332
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- 被引次数: 0
出版历程
- 收稿日期: 2023-10-08
- 修回日期: 2023-11-07
- 录用日期: 2023-11-24
- 网络出版日期: 2023-12-08
- 刊出日期: 2024-07-01

Mechanism of fiber grid reinforced with end self-locking anchorage

ZHOU Chaoyang^{1, 2},
DENG Kai²,
LIN Guozhi³,
WANG Yi^{1, 2
, ,}

1.
National Engineering Research Center of High-speed Railway Construction Technology, Central South University, Changsha 410075, China
2.
School of Civil Engineering, Central South University, Changsha 410075, China
3.
China Machinery International Engineering Design & Research Institute CO., LTD., Changsha 410007, China

Funds: National Natural Science Foundation of China (52178308); Natural Science Foundation of Hunan (2021JJ60026; 2022JJ30735); Central South University Innovation-Driven Research Program, China (2023CXQD051)

摘要

摘要: 为解决织物增强混凝土(TRC)加固混凝土梁结构界面端部剥离问题，拟采用端部自锁技术将TRC板锚固在梁底。得益于该技术提供的端部锚固作用，即使发生界面剥离，TRC板仍能继续承载。但与纤维布相比，纤维网格由于各纤维束之间间隙大得多，协同受力性能较差，在不作处理的情况下能否实现自锁尚存疑问。为了提高纤维网格强度利用率，本文通过端部自锁锚固的纤维网格拉伸试验对其端锚自锁增强效应进行了研究。对纤维网格采取增大物理摩擦或增加化学粘结等措施，进而拉伸至破坏，分析比较了各试件的破坏模式、荷载-应变曲线，提出了纤维网格增强后承载力计算公式。试验结果表明：纤维网格端部自锁锚固时的强度利用率最大提升了60.66%，通过与端部锚板的有效结合，3层网格的抗拉承载力能够达到与单层纤维布相近的水平，应用自锁锚固技术有望在TRC加固混凝土梁中解决端部界面剥离问题，提升材料利用率，改善加固效果。所提出的纤维网格增强后承载力计算公式可为相关工程实践提供有益参考。
- 纤维网格 /
- 端锚 /
- 自锁 /
- 增强效应 /
- 拉伸试验
Abstract: In order to solve the problem of interface end peeling of textile reinforced concrete (TRC) reinforced concrete beam structures, an end self-locking technique was proposed to anchor the TRC slabs at the bottom of the beams. Owing to the end anchorage provided by this technique, the TRC slab can continue to carry the load even if interfacial debonding occurs. However, compared with the fiber sheet, the fiber mesh has poor synergistic stress performance due to much larger gaps between the fiber bundles, and it is doubtful whether self-locking can be achieved without treatment. In order to improve the utilization of fiber mesh strength, this paper investigates the end-anchor self-locking enhancement effect through the end self-locking anchored fiber mesh tensile test. Measures such as increasing physical friction or adding chemical bonding to the fiber grid are taken to stretch it to failure. The failure modes and load-strain curves of each specimen are analyzed and compared, and a formula for calculating the bearing capacity of the fiber grid after enhancement is proposed. The results show that even if the size of the fiber grid is limited, the strength utilization rate of the fiber grid under end anchoring is increased by 60.66% by reinforcement measures, and the tensile bearing capacity of the three-layer grid can be similar to that of the fiber sheet. The application of the self-locking anchorage technology is expected to solve the problem of end-interface debonding in TRC-reinforced concrete beams, enhance the material utilization, and improve the strengthening effect. The proposed formula for calculating the bearing capacity after fiber mesh reinforcement can provide a useful reference for related engineering practice.
- fiber grid /
- end anchored /
- self locking /
- enhancement effect /
- tensile test

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图 1 锚固装置和网格自锁缠绕方式

Figure 1. Anchorage device and self-locking of strips

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图 2 试验流程图

Figure 2. Experimental flow

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图 3 试件加载装置及增大网格接触、夹具夹紧示意图

Figure 3. Tensile test setup and indication of increasing contact area, external force clamping

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图 4 试件准备过程(以G3FE为例)

Figure 4. Specimen preparation procedures (Take G3FE for example)

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图 5 不同工况试件拉伸-荷载位移曲线

Figure 5. Tensile load-displacement curves of different specimens

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图 6 自锁情况网格缠绕部分力学模型^[24]

Figure 6. Mechanical model of mesh winding in self-locking condition^[24]

N_IJ—Equivalent normal force of each section of the strip; f_IJ—Tangential friction force of each section of the strip; F_I—Axial force at positions I of the strip. For example, F_A and F_H—Axial forces at the ends A and H of the strip

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图 7 不同试件荷载-应变沿横向方向变化曲线

Figure 7. Load-strain curves along the horizontal direction of different specimens

δ—Coefficient of variation for fiber grid

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表 1 试件概况汇总和试验结果对比

Table 1. Summary of specimens and comparison of test results

Specimen	Experimental parameters				Performance parameters
Specimen	Layer	Whether increased contact treatment	Clamp loosened/ fastened	Whether epoxy impregnation	Ultimate load/kN	Ultimate strength/ MPa	Material strength/ MPa	Intensity utilization/ %	Theoretical/experimental values of ultimate loads/(kN·kN⁻¹)
G1OL	1	No	Loosened	No	1.9	719	2169	33.18	—
G1CL		Yes	Loosened		2	757	2169	34.93	—
G1OF		No	Fastened		4.5	1704	2169	78.59	4.4/4.5=0.98
G1FE				Yes	5.4	2035	2169	94.30	5.3/5.4=0.98
G3FE	3				16.2	2043	2169	94.30	15.9/16.2=0.98
SE	1				21.2	3173	3319	95.62	21.6/21.2=1.02
SN	1				15.2	2275	3319	68.56	—
Notes: G represents fiber grid; S represents carbon fiber reinforced polymer (CFRP) sheet; O (Overlapped) represents no treatment, i.e., the grid is overlapped vertically; C (Crossed) represents increased contact of the grid, i.e., the grid is staggered vertically; L (Loosened) represents no external force fastening, i.e., loose; F (Fastened) represents fastening with external force, i.e., tight; E (Epoxy) represents epoxy resin impregnated adhesive, N (Not) represents not impregnated. The number represents the number of layers of fiber grid. Example: G3FE represents 3 layers of fiber grid impregnated with epoxy resin and fastened with external force. Ultimate strength = Ultimate load/cross-sectional area; Intensity utilization = Ultimate strength/material strength × 100%.

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表 2 材料性能参数

Table 2. Properties of selected materials

Material	Kind	Density/(kg·m⁻²)	Theoretical thickness/mm	Elastic modulus/GPa	Tensile strength/MPa	Ultimate strain/10⁻⁶
Fiber sheet	T700 SC 12 K/0500	300	0.167	230	3319	14430
Fiber grid	CFN 200/200	—	0.047	124	2169	17520
Epoxy resin	CFSR-A/B	—	—	4.0	55	—

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表 3 不同工况试件拉伸破坏失效模式

Table 3. Tensile failure modes of specimens under different working conditions

Material	No processing	Increasing contact area	Clamp clamping	1 layer & epoxy impregnation	3 layers & epoxy impregnation
Fiber grid
Fiber sheet		—	—		—
Note:FRP-Fiber reinforced polymer

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参考文献(25)

[1]	冯鹏, 陆新征, 叶列平. 纤维增强复合材料建设工程应用技术−试验、理论与方法[M]. 北京: 中国建筑工业出版社, 2011: 2-3. FENG Peng, LU Xinzheng, YE Lieping. Application of fiber polymer in construction: Experiment, theory and methodology[M]. Beijing: China Building Industry Press, 2011: 2-3(in Chinese).
[2]	RAHIMI H, HUTCHINSON A. Concrete beams strengthened with externally bonded FRP plates[J]. Composite Construction, 2001, 5(1): 44-56. doi: 10.1061/(ASCE)1090-0268(2001)5:1(44)
[3]	CROMWELL J R, HARRIES K A, SHAHROOZ B M. Environmental durability of externally bonded FRP materials intended for repair of concrete structures[J]. Construction and Building Materials, 2011, 25(5): 2528-2539. doi: 10.1016/j.conbuildmat.2010.11.096
[4]	AKTAS M, KARAKUZU R. Determination of mechanical properties of glass-epoxy composites in high temperatures[J]. Polymer Composites, 2009, 30(10): 1437-1441. doi: 10.1002/pc.20708
[5]	JCPH G, AL-MAHAIDI R, WONG M B. Bond characteristics of CFRP plated concrete members under elevated temperatures[J]. Composite Structures, 2006, 75: 199-205. doi: 10.1016/j.compstruct.2006.04.068
[6]	XIE J H, LU Z Y, GUO Y C, et al. Durability of CFRP sheets and epoxy resin exposed to natural hygrothermal or cyclic wet-dry environment[J]. Polymer Composites, 2019, 40(2): 553-567. doi: 10.1002/pc.24687
[7]	PATRÍCIA S, PEDRO F, FERNANDO C. Effects of different environmental conditions on the mechanical characteristics of a structural epoxy[J]. Polymer Composites, 2016, 88: 55-63.
[8]	LETTIERI M, FRIGIONE M. Effects of humid environment on thermal and mechanical properties of a cold-curing structural epoxy adhesive[J]. Construction and Building Materials, 2012, 30: 753-760. doi: 10.1016/j.conbuildmat.2011.12.077
[9]	AL-LAMI K, D'ANTINO T, COLOMBI P. Durability of fabric reinforced cementitious matrix (FRCM) composites: A review[J]. Applied Sciences, 2020, 10(5): 1714. doi: 10.3390/app10051714
[10]	AYGORMEZ Y, CANPOLAT O, AL-MASHHADANI M M. Assessment of geopolymer composites durability at one year age[J]. Journal of Building Engineering, 2020, 32: 101453.
[11]	SAHMARAN M, LI V C. Durability of mechanically loaded engineered cementitious composites under highly alkaline environments[J]. Cement Concrete Composites, 2008, 30(2): 72-81. doi: 10.1016/j.cemconcomp.2007.09.004
[12]	LIU H Z, ZHANG Q, LI V, et al. Durability study on engineered cementitious composites (ECC) under sulfate and chloride environment[J]. Construction and Building Materials, 2017, 133: 171-181. doi: 10.1016/j.conbuildmat.2016.12.074
[13]	ZHU M C, ZHU J H, UEDA T, et al. Bond behavior of carbon fabric reinforced cementitious matrix (FRCM) composites considering matrix impregnation[J]. Composite Structures, 2021, 262: 113350.
[14]	RAOOF S M, KOUTAS L N, BOURNAS D A. Textile-reinforced mortar (TRM) versus fiber-reinforced polymers (FRP) in flexural strengthening of RC beams[J]. Composite Part B: Engineering, 2015, 77: 338-348. doi: 10.1016/j.compositesb.2015.03.055
[15]	PAPANICOLAOU C G, PAPANTONIOU I C. Mechanical behavior of textile reinforced concrete (TRC)/concrete composite elements[J]. Journal of Advanced Concrete Technology, 2010, 8(1): 35-47. doi: 10.3151/jact.8.35
[16]	KONG K, MESTICOU Z, MICHEL M, et al. Comparative characterization of the durability behavior of textile-reinforced concrete (TRC) under tension and bending[J]. Composite Structures, 2017, 179: 107-123. doi: 10.1016/j.compstruct.2017.07.030
[17]	徐世烺, 尹世平, 蔡新华. 纤维编织网增强混凝土加固钢筋混凝土梁受弯性能研究[J]. 土木工程学报, 2011, 44(4): 23-34. XU Shilang, YIN Shiping, CAI Xinhua. Study on bending performance of reinforced concrete beams reinforced with fiber woven mesh[J]. China Civil Engineering Journal, 2011, 44(4): 23-34(in Chinese).
[18]	YIN S P, LI Y, LI S C, et al. Seismic performance of RC columns strengthened with textile-reinforced concrete in chloride environment[J]. Journal of Composite Construction, 2020, 24(1): 04019062. doi: 10.1061/(ASCE)CC.1943-5614.0000992
[19]	张勤. 织物增强混凝土(TRC)加固RC梁正截面抗弯性能试验研究[D]. 镇江: 江苏大学, 2009. ZHANG Qin. Experimental study on bending performance of positive section RC beam reinforced with fabric reinforced concrete (TRC)[D]. Zhenjiang: Jiangsu University, 2009(in Chinese).
[20]	ZHOU C Y, YU Y N, XIE E L. Strengthening RC beams using externally bonded CFRP sheets with end self-locking[J]. Composite Structures, 2020, 241: 112070.
[21]	周朝阳, 于亚男, 熊造, 等. CFRP布端绕双杆自锁加固凝土窄梁抗弯试验[J]. 复合材料学报, 2018, 35(8): 2216-2221. ZHOU Chaoyang, YU Yanan, XIONG Zao, et al. Bending resistance test of CFRP cloth end around double rod self-locking reinforced concrete narrow beam[J]. Acta Materiae Compositae Sinica, 2018, 35(8): 2216-2221(in Chinese).
[22]	GHAHSAREH F M, MOSTOFINEJAD D. Groove classification in EBROG FRP-to-concrete joints[J]. Construction and Building Materials, 2021, 275: 122169.
[23]	中国国家标准局. 定向纤维增强塑料拉伸性能试验方法: GB/T 3354—1999[S]. 北京: 中国标准出版社, 2011. National Institute of Standards and Technology of the People's Republic of China. Test method for tensile properties of directional fiber reinforced plastics: GB/T 3354—1999[S]. Beijing: China Standards Press, 2011(in Chinese).
[24]	刘君. U形碳纤维带预应力技术及其抗剪加固持载钢筋混凝土梁的性能与设计[D]. 长沙: 中南大学, 2018. LIU Jun. Performance and design of U-shaped carbon fiber with prestressing technology and its shear reinforcement reinforced concrete beam [D]. Changsha: Central South University, 2018(in Chinese).
[25]	尹世平, 徐世烺. 纤维编织网增强混凝土的拉伸力学模型[J]. 复合材料学报, 2012, 29(5): 222-229. YIN Shiping, XU Shilang. Tensile mechanics model of fiber braided mesh reinforced concrete[J]. Acta Materiae Compositae Sinica, 2012, 29(5): 222-229(in Chinese).