GFRP筋混凝土梁耐火性能计算方法

Calculation methods for fire resistance of GFRP reinforced concrete beams

通过GFRP筋混凝土梁耐火性能的理论分析与有限元计算,提出GFRP筋混凝土结构耐火性能的计算方法。在合理选择GFRP和混凝土材料的热工参数、高温力学参数的基础上,采用有限元分析软件ABAQUS建立三面受火的GFRP筋混凝土梁的高温热力学模型。经与GFRP筋混凝土梁火灾试验结果的对比验证,该高温力学模型具有较高的精确性。对影响GFRP筋混凝土梁高温力学性能的各参数进行有限元分析,结果表明,影响梁耐火性能的主要因素为梁上作用的荷载比、GFRP筋在混凝土截面的位置和受火时间。参考欧洲规范钢筋混凝土抗火性能的设计方法,提出GFRP筋混凝土构件基于力学性能的耐火设计公式。通过混凝土500℃等温线简化受火面积和GFRP筋高温强度等效换算的方式,将火灾下截面的非均匀材料力学性质转变为随受火时间变化的均匀材料,提出了不同受火时刻GFRP筋混凝土受弯构件的承载力计算式。经与有限元分析结果的对比,该计算方法精度较高,可应用于评估不同受火时刻下GFRP筋混凝土的高温承载力。

The fire performance of concrete beams reinforced with GFRP rebar was studied in this paper by the method of numerical simulation and theoretical calculation. Finite element models of concrete beam heated by ISO 834 standard heating curve were developed, and the suitable thermal and thermodynamic parameters were selected for the analysis. The accuracy of FEA model was proved by the comparison with the results of fire experiments, and different influencing factors were taken into account for the parametric studies to describe the fire performance. FEA results indicate that the fire behavior of GFRP reinforced concrete beams is only controlled by three factors： loading rate, GFRP rebar position, and the time exposed in fire. Refer to the structure fire design of steel reinforceal concrete in Eurocode 2, the inhomogeneous material properties under fire exposure can be assumed as homogeneous by reduced cross-section of concrete. The load-bearing capacity of the GFRP reinforced concrete members in fire environment can be calculated by the reduction of concrete cross section exposed in fire and the equivalent strength of GFRP rebars in different positions with different temperatures. The theoretical design method proposed in this paper shows good agreement with FEA results, which can be used to calculate the bearing capacity of GFRP reinforced concrete beams in fire environment.