西安建筑科技大学学报(自然科学版)

采用加速老化试验方法对混凝土碱性环境中GFRP筋抗拉性能进行了研究.将112根GFRP筋混凝土试件分为6组,试验参数包括持续荷载、温度和侵蚀时间.试验结果表明,混凝土环境中GFRP筋抗拉强度在早期退化较快,试件在40 ℃、60 ℃环境中浸泡30 d后GFRP筋抗拉强度分别下降了5.4%和13.7%; 温度的升高加速了混凝土环境中GFRP筋抗拉强度的退化速率; 持续荷载水平对GFRP筋抗拉强度退化有较大影响,且随着温度的升高,持续荷载所造成退化的效果愈加显著; 最后,基于Arrhenius方程建立了实际混凝土环境下GFRP筋长期抗拉强度预测模型,并对北京、武汉和广州等地区实际混凝土环境中GFRP筋抗拉强度保留率进行了预测.

The accelerated aging tests for evaluations of tensile strength of glass fiber reinforced polymer(GFRP)bars embedded in concrete environment under sustained load were conducted. 112 GFRP reinforcement concrete specimens were used in the test and divided into 6 groups, test parameters include sustained load, temperature and exposed time. The results show that the tensile strength of GFRP bar embedded in concrete environment degraded rapidly at an early age. The specimen after being exposed to concrete environment for 30 days at 40 ℃ and 60 ℃, tensile strength of GFRP bar decreased by 5.4% and 13.7% respectively. The high temperature accelerated degradation rate of tensile strength of GFRP bars embedded in concrete environment. The tensile strength of GFRP is more affected by higher sustained load, and with the increase of temperature, the degradation effect is more significant caused by sustained load. Finally, based on the Arrhenius equation, tensile strength prediction model of GFRP bars under real concrete environment was proposed, and predicted the tensile strength retention of GFRP bars under real concrete environment on Beijing, Wuhan, and Guangzhou respectively.

引言
1 试验设计
2 结果与分析
3 混凝土环境中GFRP筋强度预测
4 结论

表1 GFRP筋力学性能指标<br/>Tab.1 Mechanical properties of the GFRP bar

表1 GFRP筋力学性能指标
Tab.1 Mechanical properties of the GFRP bar

表2 混凝土配合比<br/>Tab.2 Concrete mix proportion/kg·m-3

表2 混凝土配合比
Tab.2 Concrete mix proportion/kg·m-3

图1 GFRP筋混凝土试件(单位/mm)<br/>Fig.1 GFRP reinforced concrete beams

图1 GFRP筋混凝土试件(单位/mm)
Fig.1 GFRP reinforced concrete beams

图2 试件加载反力架设备及试验箱<br/>Fig.2 Load setup and test chamber

图2 试件加载反力架设备及试验箱
Fig.2 Load setup and test chamber

表3 试件分组
Tab.3 Test conditions

图3 不同温度下GFRP筋抗拉强度保留率<br/>Fig.3 Tensile strength retention of GFRP bar at different temperatures

图3 不同温度下GFRP筋抗拉强度保留率
Fig.3 Tensile strength retention of GFRP bar at different temperatures

图4 不同持续荷载下GFRP筋抗拉强度保留率<br/>Fig.4 Tensile strength retention of GFRP bar under different sustained load

图4 不同持续荷载下GFRP筋抗拉强度保留率
Fig.4 Tensile strength retention of GFRP bar under different sustained load

图5 GFRP筋在混凝土环境中抗拉强度退化机理示意图<br/>Fig.5 Schematic diagram for the tensile strength degradation mechanism of GFRP bar embedded in concrete environments

图5 GFRP筋在混凝土环境中抗拉强度退化机理示意图
Fig.5 Schematic diagram for the tensile strength degradation mechanism of GFRP bar embedded in concrete environments

图6 抗拉强度保留率拟合曲线<br/>Fig.6 Fitted curves for tensile strength retention

图6 抗拉强度保留率拟合曲线
Fig.6 Fitted curves for tensile strength retention

表4 拟合参数及相关系数<br/>Tab.4 The fitting parameters and the correlation coefficient

表4 拟合参数及相关系数
Tab.4 The fitting parameters and the correlation coefficient

图7 不同温度下GFRP筋达到相应抗拉强度保留率所需时间的拟合曲线<br/>Fig.7 Fitted curves for the time needed to reach a given tensile strength of GFRP bars under different temperature

图7 不同温度下GFRP筋达到相应抗拉强度保留率所需时间的拟合曲线
Fig.7 Fitted curves for the time needed to reach a given tensile strength of GFRP bars under different temperature

表5 回归方程的相关系数<br/>Tab.5 Coefficients of regression equations

表5 回归方程的相关系数
Tab.5 Coefficients of regression equations

表6 时间转换系数
Tab.6 Time shift factor

图8 不同年平均温度环境下GFRP筋抗拉强度预测曲线<br/>Fig.8 Tensile strength predicted curves of GFRP bars at different mean annual temperatures

图8 不同年平均温度环境下GFRP筋抗拉强度预测曲线
Fig.8 Tensile strength predicted curves of GFRP bars at different mean annual temperatures

表7 预测曲线回归方程系数<br/>Tab.7 Coefficient of the regression equations for the predicted curves

表7 预测曲线回归方程系数
Tab.7 Coefficient of the regression equations for the predicted curves

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备注

引言

1 试验设计

2 结果与分析

3 混凝土环境中GFRP筋强度预测

4 结论

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