湿热环境作用下CFRP加固钢筋混凝土梁的抗弯性能

江胜华; 姚国文; 刘超越; 刘晓春

doi:10.3969/j.issn.0258-2724.20170893

湿热环境作用下CFRP加固钢筋混凝土梁的抗弯性能

doi: 10.3969/j.issn.0258-2724.20170893

基金项目: 国家自然科学基金重大科研仪器研制项目（11627802）；国家自然科学基金（51478071，51208078）；重庆市基础与前沿应用研究计划（cstc2015jcyjBX0022，cstc2015jcyjA30008）；中国博士后科学基金（2017M622977）

详细信息

作者简介:
江胜华（1982—），男，副教授，博士，研究方向为结构健康监测与加固，E-mail：jiangsh@whu.edu.cn

通讯作者:
姚国文（1974—），男，教授，博士，研究方向为桥梁损伤机理与检测加固，E-mail：yaoguowen@sina.com

中图分类号: TU470
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出版历程
- 收稿日期: 2018-02-09
- 修回日期: 2018-05-23
- 网络出版日期: 2018-05-31
- 刊出日期: 2020-02-01

Flexural Behavior of Reinforced Concrete Beams Strengthened with Carbon Fiber Reinforced Polymer under Hydrothermal Environment

摘要

摘要: 为研究湿热环境下碳纤维增强复合材料（CFRP）加固钢筋混凝土结构的耐久性问题，采用6根湿热环境下CFRP加固的钢筋混凝土梁进行抗弯性能试验，研究在湿热环境下CFRP加固钢筋混凝土梁的破坏形态、承载力、挠度和裂缝等；根据环氧树脂老化的化学反应微分方程和反应速度的指数定律，给出环氧树脂胶层弹性模量的衰减模型；从混凝土和环氧树脂胶层的力学性能出发，提出湿热环境下CFRP加固钢筋混凝土结构后CFRP剥离时的强度计算公式，推导湿热环境作用下CFRP加固钢筋混凝土梁的抗弯承载力计算公式. 研究结果表明：随着湿热环境作用时间的增加，加固梁的抗弯承载力逐渐减小，CFRP剥离破坏由混凝土控制逐渐转换为由环氧树脂胶层控制；随着湿热环境作用的持续，混凝土裂缝数量减小、裂缝宽度增加但挠度减小，加固梁的损伤增大且脆性增加；加固梁的屈服曲率、极限曲率和曲率延性系数均减小，加固梁的延性变差且CFRP剥离破坏时的脆性和离散性增强；试验与理论计算的对比表明，在湿热环境作用下加固梁发生CFRP剥离破坏时，CFRP极限应变的理论值与试验值误差在20%以内，抗弯承载力的理论值与试验值误差在11%以内.
- 碳纤维布 /
- 剥离 /
- 湿热环境 /
- 环氧树脂 /
- 反应速度
Abstract: To study the durability of concrete structure strengthened with CFRP(carbon fiber reinforced polymer) under hydrothermal environment, six concrete beams strengthened with CFRP under warm and moisture conditions were used for flexural behavior experiment; the failure mode, bearing capacity, deflection and crack were studied by the experiment. Based on differential equations of chemical reactions and exponential law of reaction rate for epoxy resin aging, the attenuation model of elastic modulus was given for epoxy resin under warm and moisture conditions. From the mechanical properties of concrete and epoxy resin, theoretical formula of CFRP peel strength was given for concrete beams strengthened with CFRP under hydrothermal environment, and the flexural capacity formula was also put forward. The results show that the flexural capacity of strengthened concrete beams decrease exposed to environmental conditions, and peeling failure of CFRP is gradually transferring from the interface region of concrete side to the interface region of CFRP side. As the environmental effect continues, the number of cracks and deflection reduce while the crack width increases, which show that both damage and brittleness of strengthened beam increases. The yield curvature, ultimate curvature and curvature ductility factor of the strengthened beam reduce, and it indicates that the ductility of the strengthened beam deteriorates, but the brittleness and dispersion of the CFRP peeling failure increase. The comparison between the experimental and theoretical analysis shows that the relative error of the theoretical and the experimental value is smaller than 20% for CFRP ultimate strain, and the relative error is smaller than 11% for flexural capacity.
- carbon fiber reinforced polymer sheet /
- peeling /
- hydrothermal environment /
- epoxy resin /
- reaction rate

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图 1 加固梁的尺寸及配筋

Figure 1. Dimension and reinforcement of concrete beam

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图 2 试件破坏形态

Figure 2. Failure mode of concrete beam

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图 3 湿热环境下混凝土抗压强度、环氧树脂胶层弹性模量与时间的关系

Figure 3. Relation ships between concrete compressive strength，epoxy resin’s elastic modulus and exposure duration

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图 4 湿热环境下CFRP剥离强度与时间的关系

Figure 4. Relation ships between CFRP’s peel strength and exposure duration

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图 5 湿热环境下加固梁的抗弯承载力与时间的关系

Figure 5. Relation ships between flexural capacity and exposure duration

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表 1 钢筋的实测力学性能

Table 1. Mechanical property of steel

类别	型号	屈服强度/MPa	极限强度/MPa	延伸率%	弹性模量/GPa	塑性模量/GPa
受拉纵筋	Ф10	333.3	506.5	34.6	204	7.18
架立钢筋和箍筋	Ф8	310.0	500.0	23.0	194	—

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表 2 CFRP的力学性能

Table 2. Mechanical property of CFRP

规格	理论厚度/mm	抗拉强度/MPa	弹性模量/GPa	伸长率/%
WF300	0.167	3 609	243.0	1.71

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表 3 环氧树脂粘结剂的力学性能

Table 3. Mechanical property of epoxy resin MPa

规格	弹性模量	拉伸强度	压缩强度	剪切强度	弯曲强度
JGN-II	≥ 2 500	≥ 40	≥ 70	≥ 14	≥ 50

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表 4 试验梁参数

Table 4. Parameters of experimental beams

试验梁编号	混凝土	配筋	粘贴层数/层	试验环境	环境作用时间/d
L1	C30	2Φ10	1	正常	0
L2	C30	2Ф10	1	湿热	5
L3	C30	2Ф10	1	湿热	10
L4	C30	2Ф10	1	湿热	15
L5	C30	2Ф10	1	湿热	30
L6	C30	2Ф10	1	湿热	60

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表 5 承载力试验结果

Table 5. Experimental results

试验梁编号	试验环境	环境用时间/d	开裂荷载/kN	与 L1 的比值/%	屈服荷载/kN	与 L1 的比值/%	极限荷载/kN	与 L1 的比值/%	CFRP极限应变/× 10⁻⁶	与 L1 的比值/%	破坏形态
L1	正常	0	8.80	100	26.73	100	40.01	100	6 926	100	中部裂缝处剥离
L2	湿热	5	8.90	101	24.96	94	40.42	101	6 527	94
L3	湿热	10	10.59	120	24.10	90	39.62	99	6 061	88
L4	湿热	15	10.82	123	22.99	86	39.29	98	6 018	87
L5	湿热	30	9.54	108	23.10	87	38.51	96	5 733	83
L6	湿热	60	7.30	83	22.71	85	37.20	93	5 150	74

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表 6 裂缝与挠度试验结果

Table 6. Experimental results of crack and deflection

试验梁编号	试验环境	环境作用时间/d	裂缝数量	与 L1 的比值/%	平均裂缝间距/mm	与 L1 的比值/%	最大裂缝宽度/mm	与 L1 的比值/%	极限挠度/mm	与 L1 的比值/%
L1	正常	0	11	100	96.8	100	0.86	100	12.36	100
L2	湿热	5	11	100	86.4	89	0.91	106	11.91	96
L3	湿热	10	10	91	89.6	93	0.95	110	11.83	96
L4	湿热	15	10	91	98.4	102	1.04	121	10.05	81
L5	湿热	30	9	82	106.2	110	1.12	130	9.91	80
L6	湿热	60	9	82	101.5	105	1.17	136	8.46	68

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表 7 曲率延性

Table 7. Experimental results of curvature ductility

试验梁编号	试验环境	环境作用时间/d	屈服曲率 /（× 10⁻⁶•mm⁻¹）	与 L1 的比值/%	极限曲率 /（× 10⁻⁶•mm⁻¹）	与 L1 的比值/%	曲率延性系数	与 L1 的比值/%
L1	正常	0	14.88	100	58.25	100	3.91	100
L2	湿热	5	14.84	99.7	53.02	91.0	3.57	91.3
L3	湿热	10	14.89	100	50.58	86.8	3.40	87.0
L4	湿热	15	14.72	98.9	53.48	91.8	3.63	92.8
L5	湿热	30	14.71	98.9	52.79	90.6	3.59	91.8
L6	湿热	60	14.67	98.6	49.62	85.2	3.38	86.4

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表 8 弹性模量衰减与时间的关系

Table 8. Relationship between β_aa and d

d/d	0	5	10	15	30	60
β_aa	1.00	0.90	0.85	0.80	0.75	0.66

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表 9 理论值与试验值的比较

Table 9. Comparison between theoretical and experimental values

试验梁编号	试验环境	环境作用时间/d	CFRP 极限应变/× 10⁻⁶			极限荷载/kN
试验梁编号	试验环境	环境作用时间/d	试验值	理论值	比值/%	试验值	理论值	比值/%
L1	正常	0	6 926	6 362	92	40.01	35.81	90
L2	湿热	5	6 527	6 322	97	40.42	35.73	89
L3	湿热	10	6 061	6 319	104	39.62	35.72	90
L4	湿热	15	6 018	6 311	105	39.29	35.71	91
L5	湿热	30	5 733	6 280	110	38.51	36.65	95
L6	湿热	60	5 150	6 200	120	37.20	35.50	95

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