混凝土结构在高温作用下,结构的力学性能会发生较大劣化.结构性能的劣化使得结构的实际可靠度比设计可靠度低.考虑了高温下塑性区混凝土对结构抗力的贡献,提出了一种简便可行的钢筋混凝土构件抗力随受火时间变化的模型及火灾作用下可靠性指标的分析方法.采用一次二阶矩方法计算了可靠度指标,以评估在ISO834标准升温曲线作用下混凝土结构的可靠度.算例表明,随着火灾作用时间的增加,混凝土结构的可靠度显著降低,该方法可用于火灾环境下钢筋混凝土结构可靠度评估.%Due to the mechanical properties of reinforced concrete under high temperatures showing significant deterioration, the reliability of reinforced concrete beams is largely discounted. The resistance of concrete in plastic zone under high temperatures was considered in this paper. A simple and feasible time-variant model of the resistance of reinforced concrete beams in fire was given along with a reliability index analysis method of the beams. The reliability of a reinforced concrete beam under the ISO834 standard heating curve was assessed by the first order second moment method. The result shows that, with the increase of the duration of fire action, the reliability of concrete structures is significantly reduced. This method may be used in reliability assessment of reinforced concrete structures under an environment with fire.
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