既有钢筋混凝土梁时变可靠度计算模型

Calculating models of time-dependent reliability for existing reinforced concrete beam

分析了目前既有结构时变可靠度计算理论和现行规范计算公式,考虑混凝土损伤和钢筋锈蚀以及材料强度随时间劣化的情况,建立了既有钢筋混凝土梁(单筋矩形截面、双筋矩形截面和T形截面)的时变抗力计算模型,给出了既有钢筋混凝土梁的时变可靠度指标,并通过工程实例对既有钢筋混凝土梁进行了加固前计算分析。结果表明:实例结构动态可靠度指标为1.56,承载能力属于d级,这与现行可靠性鉴定标准的评级相吻合,因此,计算模型合理可靠。

The current theory of time-dependent reliability for existing structures and the calculating formula in current standard were analyzed. Considering the condition of material strength deterioration with time and the damages of concrete and steel, time-dependent strength calculating models were built for single-side reinforced concrete beam with rectangular section, double reinforced concrete beams with rectangular section and T-shape section. The time-dependent reliability index was put forward, and an engineering example was studied. Analysis result shows that the reliability index of existing reinforced concrete beam is 1.56, its bearing capacity belongs to grade d and is fit with current reliability appraisal standard, so the calculating models are correct and reasonable.1 tab, 2 figs, 14 refs.