高温下CFRP筋及其粘结型锚固系统的力学性能

苏捷; 李权浩; 方志; 蒋正文; 方川; 王志伟

doi:10.13801/j.cnki.fhclxb.20211214.003

高温下CFRP筋及其粘结型锚固系统的力学性能

doi: 10.13801/j.cnki.fhclxb.20211214.003

苏捷^{1, 2},
李权浩¹,
方志^{1, 2},
蒋正文^{1, 2, ,},
方川¹,
王志伟³

1.
湖南大学　土木工程学院，长沙 410082
2.
湖南大学　风工程与桥梁工程湖南省重点实验室，长沙 410082
3.
中复碳芯电缆科技有限公司，连云港 222069

基金项目: 国家自然科学基金(51908206；51408213)

详细信息

通讯作者:
蒋正文，博士，副教授，研究方向为高性能材料结构抗火性能　E-mail：jiangzw@hnu.edu.cn

中图分类号: TU502
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- 被引次数: 0
出版历程
- 收稿日期: 2021-11-03
- 修回日期: 2021-12-01
- 录用日期: 2021-12-02
- 网络出版日期: 2021-12-15
- 刊出日期: 2022-11-01

Mechanical properties of CFRP bar and bond-type anchorage system exposed to elevated temperature

SU Jie^{1, 2},
LI Quanhao¹,
FANG Zhi^{1, 2},
JIANG Zhengwen^{1, 2
, ,},
FANG Chuan¹,
WANG Zhiwei³

1.
College of Civil Engineering, Hunan University, Changsha 410082, China
2.
Key Laboratory for Wind and Bridge Engineering of Hunan Province, Hunan University, Changsha 410082, China
3.
Zhongfu Carbon Fiber Core Cable Technology CO., LTD., Lianyungang 222069, China

摘要

摘要: 为明确高温下碳纤维增强复合材料(Carbon fiber reinforced polymer，CFRP)筋及其以活性粉末混凝土(RPC)为粘结介质的粘结型锚固系统的力学性能，以处理温度为试验参数，完成了12个筋材试件的高温轴拉试验和8个锚固性能试件的高温拉拔试验。揭示了处理温度对高温下CFRP筋及其粘结型锚固系统力学性能的影响规律，建立了适于分析高温下CFRP筋轴向拉伸性能、以RPC为粘结介质的粘结型锚固系统粘结强度及临界锚固长度的实用计算公式。结果表明：对于筋材轴拉试件，100℃、210℃和300℃下筋材的抗拉强度、弹性模量较常温试件分别下降了(2.3%、11.4%)、(29.8%、35.6%)和(40.9%、45%)，高温下筋材的弹性模量较抗拉强度受处理温度的影响更为显著；100℃、210℃和300℃下筋材的极限拉应变较常温试件分别增大了18.5%、17.3%和14.8%，高温下筋材的极限拉应变随处理温度升高而呈先增大后减小的变化趋势；对于锚固性能试验，试件的粘结强度随处理温度升高而线性衰减，处理温度为100℃、210℃与300℃试件的粘结强度较常温试件分别下降了20.4%、52.6%和85.1%。文中所建立的高温下CFRP筋与粘结型锚固系统力学性能的实用计算公式均具有较高精度。
- CFRP筋 /
- 粘结型锚固系统 /
- 高温轴拉性能 /
- 高温锚固性能 /
- 临界锚固长度
Abstract: To determine the elevated-temperature mechanical properties of carbon fiber reinforced polymer (CFRP) bar and its bond-type anchorage system with bonding agent of reactive powder concrete (RPC), the axial tensile tests and pull-out tests with parameter of treatment temperature were conducted on 12 CFRP bar specimens and 8 anchorage performance specimens exposed to elevated temperature, respectively. The effects of elevated temperature on the mechanical properties of CFRP bar and its bond-type anchorage system under high tempera-ture were uncovered, and the practical formulas were developed for determining the axial tensile properties of CFRP bar, the bond strength and the critical anchorage length of the bond-type anchorage system with bonding agent of RPC exposed to elevated temperature. The results demonstrated that the tensile strength and elastic modulus of axial tensile specimens exposed to the elevated temperature of 100℃, 210℃ and 300℃ decreased by (2.3%, 11.4%), (29.8%, 35.6%) and (40.9%, 45%), respectively, compared to the specimen under room temperature. The effect of elevated temperature on the elastic modulus of CFRP bar exposed to elevated temperature was more significant than the tensile strength. The ultimate tensile strain of axial tensile specimens exposed to the elevated temperature of 100℃, 210℃ and 300℃ increased by 18.5%, 17.3% and 14.8%, respectively, compared to the specimen under room temperature. With the increase of the elevated temperature, the ultimate tensile strain of CFRP bar increased firstly and then decreased. The bond strength of the anchorage performance specimens decreased linearly with the increase of the elevated temperature. Specifically, compared to the specimen under room temperature, the bond strengths of the specimens exposed to the elevated temperature of 100℃, 210℃ and 300℃ decreased by 20.4%, 52.6% and 85.1%, respectively. The practical formulas with high accuracy for determining the mechanical properties of the CFRP bar and bond-type anchorage system exposed to elevated temperature were developed in the present study.
- CFRP bar /
- bond-type anchorage system /
- axial tensile performance under elevated temperature /
- anchorage performance under elevated temperature /
- critical anchorage length

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图 1 碳纤维增强聚合物复合材料(CFRP)筋轴拉试件

Figure 1. Axial tensile specimen of carbon fiber reinforced polymer (CFRP) bar

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图 2 CFRP筋-活性粉末混凝土(RPC)锚固性能试件

Figure 2. Anchorage performance specimen of CFRP bar-reactive powder concrete (RPC)

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图 3 CFRP筋及其外观尺寸

Figure 3. CFRP bar and its external dimensions

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图 4 轴拉试验的温升及加载装置

MTS—Mechanical testing and simulation

Figure 4. Setups of elevated temperature and loading of axial tensile test

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图 5 锚固性能试验的温升及加载装置

Figure 5. Setups of elevated temperature and loading of anchorage performance test

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图 6 温升及加载过程

Figure 6. Processes of elevated temperature and loading

T₀—Room temperature; T_a—Target temperature; P_u—Ultimate load; T—Temperature; P—Load; t—Time; t₀—Test start time; t₁—Time to target temperature; t₂—Start load time; t₃—Time to failure

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图 7 CFRP筋轴拉试件的破坏形态

Figure 7. Typical failure modes of CFRP bar axial tensile specimens

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图 8 CFRP筋轴拉试件的应力-应变曲线

Figure 8. Stress-strain curves of CFRP bar axial tensile specimen

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图 9 高温下CFRP筋轴拉性能衰减规律

$f_u(T)/f_u $—Reduction coefficient of tensile strength under high-temperature; $E_u(T)/E_u $—Reduction coefficient of elastic modulus under high-temperature; $\varepsilon _u(T)/\varepsilon_u $—Reduction coefficient of ultimate tensile strain under high-temperature

Figure 9. Decay law of axial tensile performance of CFRP bar exposed to elevated temperature

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图 10 CFRP筋-RPC锚固性能试件破坏形态

Figure 10. Typical failure modes of CFRP bar-RPC anchorage performance specimens

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图 11 高温下CFRP筋-RPC锚固性能试件的粘结-滑移曲线

Figure 11. Bond-slip curves of CFRP bar-RPC anchorage performance specimens exposed to elevated temperature

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图 12 处理温度对CFRP筋-RPC界面黏结强度的影响

Figure 12. Effect of elevated temperature on bond strength of CFRP bar-RPC interface

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图 13 (T−T₀)/T_g对高温下CFRP筋轴拉性能的影响

Figure 13. Effect of (T−T₀)/T_g on axial tensile performance of CFRP bar exposed to elevated temperature

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表 1 CFRP筋外观尺寸及玻璃化转变温度T_g

Table 1. Dimensions and glass transition temperatureT_g of CFRP bar

Nominal diameter/mm	Rib width/mm	Rib height/mm	Embossing space/mm	T_g/℃
12	9.26	0.27	14.8	210

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表 2 RPC配合比及抗压强度

Table 2. Mix proportion and compressive strength of RPC

Strength grade	Cement	Silica fume	Quartz flour	Quartz sand	Water reducer	Water binder ratio
RPC150	1	0.25	0.25	1.1	0.02	0.16

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表 3 CFRP筋轴向拉伸试验结果

Table 3. Results of axial tensile test for CFRP bar

Specimen	P_u/kN	f_u/MPa	$ {\overline f _{\text{u}}}/{\text{MPa}} $	E/GPa	$ \overline E /{\text{GPa}} $	$ { \varepsilon _{\text{u}}}/{10^{ - 6}} $	$ {\overline \varepsilon _{\text{u}}}/{10^{ - 6}} $
AT-T25-1	280.8	2631	2650	162.2	159.9	15627	15513
AT-T25-2	283.1	2653		161.8		15464
AT-T25-3	284.5	2666		155.6		15448
AT-T100-1	274.2	2569	2588	133.0	141.6	18506	18387
AT-T100-2	278.0	2605		143.5		18343
AT-T100-3	276.3	2589		148.3		18312
AT-T210-1	198.9	1864	1861	98.7	102.9	18298	18201
AT-T210-2	192.7	1806		105.5		18254
AT-T210-3	204.3	1914		104.4		18051
AT-T300-1	176.0	1649	1566	82.6	87.9	17963	17816
AT-T300-2	157.0	1471		92.4		17762
AT-T300-3	168.3	1577		88.8		17723
Notes: In the specimen code, AT is axial tensile, T indicates the treatment temperature, the last number indicates the same specimen number; P_u—Ultimate bearing capacity; f_u—Tensile strength; $ {\overline f _{\text{u}}} $—Average value; E—Elastic modulus; $ \overline E $—Average value; $ { \varepsilon _{\text{u}}}$—Ultimate tensile strain; $ {\overline \varepsilon _{\text{u}}} $—Average value.

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表 4 CFRP筋-RPC锚固性能试验结果

Table 4. Results of CFRP bar-RPC anchorage performance test

Specimen	T/℃	P_u/kN	$ {\overline P _{\text{u}}}/{\text{kN}} $	τ_u/MPa	s/mm	$ \overline s_{\rm{u}} /{\text{mm}} $
A-T25-L5d-1	25	66.74	66.38	29.36	6.74	6.67
A-T25-L5d-2	25	66.02	66.38	29.36	6.60	6.67
A-T100-L5d-1	100	50.58	52.84	23.37	6.44	6.53
A-T100-L5d-2	100	55.10	52.84	23.37	6.62	6.53
A-T210-L5d-1	210	34.30	31.47	13.92	5.88	6.01
A-T210-L5d-2	210	28.64	31.47	13.92	6.14	6.01
A-T300-L5d-1	300	11.85	9.85	4.36	5.69	5.63
A-T300-L5d-2	300	7.85	9.85	4.36	5.57	5.63
Notes: In the specimen code, A is anchorage, T indicates the treatment temperature, the last number indicates the same specimen number; T—Treatment temperature; L—Bond length; τ_u—Average bond strength; s—Slip of loading end corresponding to P_u; d—Diameter of CFRP bar; $\bar P_{\rm{u}} $—Average value of ultimate bearing capacity for anchorage system; $\bar s_{\rm{u}} $—Average value of the slip of loading end corresponding to P_u。

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表 5 CFRP筋轴拉试件极限拉应变试验值与计算值对比

Table 5. Comparison of measured and predicted ultimate tensile strain of CFRP bar axial tensile specimens

Specimen	ε_u,t/10⁻⁶	ε_u,c/10⁻⁶	ε_u,t/ε_u,c
AT-T25	15513	15513	1.000
AT-T100	18387	17902	1.030
AT-T210	18201	18227	0.999
AT-T300	17816	17852	0.998
Average			1.010
Variation coefficient			0.01
Note: ε_u,t, ε_u,c—Experimental and calculated values of ultimate tensile strain of axial tensile specimen respectively.

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表 6 CFRP筋-RPC界面粘结强度试验值与计算值对比

Table 6. Comparison between measured and predicted bond strength of CFRP bar-RPC interface

Specimen	f_cu/MPa	τ_u,t/MPa	τ_u,c/MPa	τ_u,t/τ_u,c
A-T25-L5d	158	29.36	29.89	0.98
A-T100-L5d	158	23.37	23.06	1.01
A-T210-L5d	158	13.92	13.04	1.07
A-T300-L5d	158	4.36	4.84	0.90
Average				0.99
Variation coefficient				0.06
Notes: f_cu—Cube compressive strength of RPC; τ_u,t, τ_u,c—Experimental and calculated values of interfacial bond strength between CFRP bars and RPC, respectively.

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表 7 CFRP筋-RPC锚固性能试件临界锚固长度计算值及预测的破坏形态

Table 7. Critical anchorage length determined by formula and predicted failure mode of CFRP bar-RPC anchorage performance test

Specimen	T/℃	Anchorage length/mm	Actual failure mode	Critical anchorage length/mm	Predicted failure mode
A-T25-L5d	25	60	Slip	304.9	Slip
A-T100-L5d	100			389.0
A-T210-L5d	210			497.8
A-T300-L5d	300			1142.9

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