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火灾高温后混凝土内GFRP筋剪切性能退化试验与理论

陆春华 漆仲浩 葛浩 张云舒 张虹宇

陆春华, 漆仲浩, 葛浩, 等. 火灾高温后混凝土内GFRP筋剪切性能退化试验与理论[J]. 复合材料学报, 2023, 40(12): 6756-6765. doi: 10.13801/j.cnki.fhclxb.20230314.002
引用本文: 陆春华, 漆仲浩, 葛浩, 等. 火灾高温后混凝土内GFRP筋剪切性能退化试验与理论[J]. 复合材料学报, 2023, 40(12): 6756-6765. doi: 10.13801/j.cnki.fhclxb.20230314.002
LU Chunhua, QI Zhonghao, GE Hao, et al. Experimental and theoretical investigation on shear performance degradation of GFRP bars in concrete after fire and high temperature[J]. Acta Materiae Compositae Sinica, 2023, 40(12): 6756-6765. doi: 10.13801/j.cnki.fhclxb.20230314.002
Citation: LU Chunhua, QI Zhonghao, GE Hao, et al. Experimental and theoretical investigation on shear performance degradation of GFRP bars in concrete after fire and high temperature[J]. Acta Materiae Compositae Sinica, 2023, 40(12): 6756-6765. doi: 10.13801/j.cnki.fhclxb.20230314.002

火灾高温后混凝土内GFRP筋剪切性能退化试验与理论

doi: 10.13801/j.cnki.fhclxb.20230314.002
基金项目: 国家自然科学基金(51878319;51578267)
详细信息
    通讯作者:

    陆春华,博士,教授,硕士生/博士生导师,研究方向为混凝土结构基本性能及耐久性、FRP筋混合配筋混凝土结构性能E-mail: lch79@ujs.edu.cn

  • 中图分类号: TU524;TB33

Experimental and theoretical investigation on shear performance degradation of GFRP bars in concrete after fire and high temperature

Funds: National Natural Science Foundation of China (51878319; 51578267)
  • 摘要: 为研究火灾高温后混凝土内玻璃纤维增强树脂复合材料(GFRP)筋材的剪切性能,选取了100℃、150℃、200℃、300℃、350℃、400℃、500℃、650℃及800℃共9个温度工况,对混凝土内GFRP筋进行了高温作用及水平剪切试验;结合本试验及已有相关试验结果,对高温后混凝土内GFRP筋水平剪切强度预测方法进行了探讨。试验及分析结果表明:300℃高温以内,混凝土内GFRP筋表面温度存在滞后现象,其高温劣化程度明显低于裸筋,剪切强度退化也较缓慢;随着温度超过300℃及混凝土表面裂缝不断发展,内部GFRP筋受高温侵蚀逐步加大,剪切强度出现急剧下降,并出现与裸筋相似的退化规律;在300℃(接近树脂热分解温度)高温下,GFRP筋剪切强度随恒温时间的增加而线性下降,恒温1~3 h时其剪切强度保留率从76.4%降为46.5%。结合双曲正切函数模型,建立了高温后混凝土内GFRP筋水平剪切强度预测模型,其预测值与试验值吻合较好。最后,以剪切强度保留系数0.7为基准,给出了不同保护层厚度下GFRP筋的耐火时间预测值,供工程应用参考。

     

  • 图  1  混凝土试件详图

    Figure  1.  Detailed pictures of concrete specimens

    图  2  混凝土试件的热电偶布置及受热面

    Figure  2.  Thermocouple arrangement and heated surfaces of concrete specimens

    t—Top surface; s—Side surface at left; s'—Side surface at right

    图  3  800℃工况升温曲线

    Figure  3.  Heating curves under target temperature of 800°C

    图  4  水平剪切试验装置

    Figure  4.  Device for horizontal shear test

    图  5  不同温度工况下混凝土外观变化

    Figure  5.  Appearance changes of concrete under different temperature conditions

    图  6  混凝土与筋材表面的升温过程对比

    Figure  6.  Comparison of heating processes between the surfaces of concrete and bar

    图  7  高温后GFRP筋的外观形态

    Figure  7.  Appearance of GFRP bars after exposure to high temperatures

    图  8  GFRP筋水平剪切的荷载-位移曲线

    Figure  8.  Load-displacement curves of GFRP bars in horizontal shear tests

    图  9  GFRP筋的剪切破坏形态及端部详图

    Figure  9.  Shear failure modes and end details of tested GFRP bars

    图  10  高温后混凝土内GFRP筋水平剪切强度保留率

    Figure  10.  Retention rate of horizontal shear strength of GFRP bars embedded in concrete after high temperature

    图  11  高温后混凝土内GFRP筋水平剪切强度预测模型对比分析

    Figure  11.  Comparative analysis of prediction models for horizontal shear strength of GFRP bars embedded in concrete after high temperature

    R2—Correlation coefficient

    图  12  火灾中混凝土构件内部温度场

    Figure  12.  Temperature fields inside concrete components in fires

    C—Thickness of concrete cover

    图  13  GFRP筋水平剪切强度保留系数预测值

    Figure  13.  Prediction values for horizontal shear strength retention factor of GFRP bars after high temperature

    NT—Shear strength retention coefficient; T—Temperature

    表  1  玻璃纤维增强树脂复合材料(GFRP)筋基本力学性能

    Table  1.   Basic mechanical properties of glass fiber reinforced polymer (GFRP) bars

    Bar typeTensile strength/MPaTensile elastic modulus/GPaBending strength/MPaHorizontal shear strength/MPa
    GFRP884.632.8875.847.7
    下载: 导出CSV

    表  2  混凝土配合比及基本参数

    Table  2.   Concrete mix ratio and basic parameters

    Strength grade of concreteWater binder ratioMaterial/(kg·m−3)Measured compressive strength/MPa
    WaterCementSandStones
    C300.49220449615111633.8
    下载: 导出CSV

    表  3  不同温度工况下GFRP筋的水平剪切强度及保留率

    Table  3.   Horizontal shear strength and retention rate of GFRP bars under different temperature conditions

    T/℃F/NS/MPaStatistical characteristicsR/%
    No.1No.2No.3No.1No.2No.3μ/MPaCOV
    20 7995.3 8607.5 7656.2 47.1 50.8 45.1 47.7 0.06 100.0
    100 7791.4 7415.2 7379.4 45.9 43.7 43.5 44.4 0.03 93.1
    150 6976.8 7375.1 7878.1 41.1 43.5 46.5 43.7 0.06 91.6
    200 6480.6 6766.1 6707.3 38.2 39.9 39.6 39.2 0.02 82.3
    300 6564.2 5134.5 6827.3 38.7 30.3 40.3 36.4 0.15 76.4
    350 1654.7 1006.1 1335.2 9.8 5.9 7.9 7.9 0.24 16.5
    400 315.5 1333.5 1.9 7.9 4.9 0.87 10.2
    500 266.9 326.1 1.6 1.9 1.7 0.14 3.7
    Notes: T—Temperature; F—Maximum load; S—Horizontal shear strength; μ—Average value; COV—Coefficient of variation; R—Retention rate of horizontal shear strength.
    下载: 导出CSV

    表  4  300℃下不同恒温时间t作用后GFRP筋水平剪切强度及保留率

    Table  4.   Horizontal shear strength and retention rate of GFRP bars after different constant temperature time t at 300℃

    t/hF/NS/MPaStatistical characteristicsR/%
    No.1No.2No.3No.1No.2No.3μ/MPaCOV
    16563.35134.46828.338.730.340.336.40.1576.4
    25784.64268.15111.334.125.230.129.80.1562.5
    34315.83798.13232.125.522.419.122.30.1446.5
    下载: 导出CSV

    表  5  不同保护层厚度下GFRP筋的耐火时间

    Table  5.   Fire resistance time for GFRP bars with different cover thickness

    Case C/mm tf
    Case one 40 65
    Case two 50 83
    Case three 60 190
    Note: tf—Fire resistance time.
    下载: 导出CSV
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出版历程
  • 收稿日期:  2023-01-03
  • 修回日期:  2023-03-08
  • 录用日期:  2023-03-09
  • 网络出版日期:  2023-03-15
  • 刊出日期:  2023-12-01

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