HRB500钢筋混凝土并筋梁极限状态可靠度研究

发布时间：2019-06-06 02:18

【摘要】：随着高层、大跨度建筑在我国建筑中越来越多,其在受力集中部位由于配筋都比较密集,通常采用并筋这种配筋形式。国家在规范中推广使用高强钢筋作为受力钢筋。高强钢筋和并筋都对梁受弯承载力、裂缝宽度和挠度有所影响,进而影响钢筋混凝土梁的可靠度。本文将对HRB500级钢筋混凝土并筋梁受弯承载力极限状态和正常使用极限状态可靠度进行研究。本文收集了并筋梁有关受弯承载力、裂缝宽度和挠度的试验数据,统计分析并筋后钢筋混凝土梁受弯承载力、裂缝宽度和挠度的变化。结合承受荷载、计算模式、结构几何尺寸、材料参数等随机变量,先通过验算点法得到各随机变量的灵敏度系数,再根据灵敏度系数的大小对随机变量作定量分析,初步判断并筋和高强钢筋对随机变量的影响大小。然后通过验算点法计算结构构件在不同随机变量影响下的可靠指标,具体分析随机变量对结构可靠度的影响以及HRB500级钢筋和并筋对结构可靠度的影响。得出以下结论:(1)通过对梁受弯承载力可靠度分析,研究表明:HRB500级钢筋与普通钢筋相比对可靠度的影响较小;并筋对钢筋混凝土梁受弯承载力极限状态可靠度有不利影响,在并筋梁计算受弯承载力时需要考虑并筋的不利影响。(2)通过对梁最大裂缝宽度和挠度的可靠度灵敏性研究,研究表明:荷载比值对梁最大裂缝宽度和挠度可靠指标的影响最大,对裂缝和挠度可靠指标起决定性作用;计算模式不确定性系数的影响其次;混凝土强度等级、混凝土保护层厚度、裂缝限值和挠度限值的影响较小。(3)通过对并筋梁最大裂缝宽度和挠度的可靠度分析,研究表明:并筋梁的可靠指标均大于单筋梁的可靠指标,并筋混凝土梁可按我国现行混凝土设计规范最大裂缝宽度和挠度计算公式设计。
[Abstract]:With the increase of high-rise buildings, there are more and more long-span buildings in our country. Because of the dense reinforcement in the concentrated part of the force, the reinforcement form of parallel reinforcement is usually adopted. The high strength steel bar is popularized and used as the stress steel bar in the national code. Both high strength steel bar and parallel reinforcement have influence on the bending bearing capacity, crack width and deflection of the beam, and then affect the reliability of the reinforced concrete beam. In this paper, the ultimate state of bending capacity and the reliability of normal service limit state of HRB500 reinforced concrete beams are studied. In this paper, the experimental data of bending bearing capacity, crack width and deflection of reinforced concrete beams are collected, and the changes of bending capacity, crack width and deflection of reinforced concrete beams after reinforcement are statistically analyzed. Combined with random variables such as load bearing, calculation mode, structural geometric size, material parameters and so on, the sensitivity coefficients of each random variable are obtained by checking point method, and then the random variables are quantitatively analyzed according to the size of sensitivity coefficient. The influence of parallel reinforcement and high strength steel bar on random variables is preliminarily judged. Then the reliability index of structural components under the influence of different random variables is calculated by checking point method, and the influence of random variables on structural reliability and the influence of HRB500 steel bar and parallel reinforcement on structural reliability are analyzed in detail. The following conclusions are drawn: (1) through the reliability analysis of the bending bearing capacity of the beam, the results show that the HRB500 steel bar has little effect on the reliability compared with the ordinary steel bar; The joint reinforcement has an adverse effect on the ultimate state reliability of the bending capacity of reinforced concrete beams, and the adverse effects of parallel reinforcement should be considered when calculating the bending capacity of reinforced concrete beams. (2) the reliability sensitivity of the maximum crack width and deflection of the beam is studied by means of the reliability sensitivity of the maximum crack width and deflection of the beam. The results show that the load ratio has the greatest influence on the maximum crack width and deflection reliability index of the beam, and plays a decisive role in the crack and deflection reliability index. The influence of calculating the uncertainty coefficient of the model is followed by the influence of the uncertainty coefficient of the calculation model. The strength grade of concrete, the thickness of concrete protective layer, the limit value of crack and the limit value of deflection have little influence. (3) through the reliability analysis of the maximum crack width and deflection of reinforced beam, The results show that the reliability index of the parallel reinforced beam is higher than that of the single reinforced beam, and the reinforced concrete beam can be designed according to the formula for calculating the maximum crack width and deflection in the current concrete design code of our country.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU375.1

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