开裂在役钢筋混凝土梁加卸载刚度与正常使用可靠度分析

发布时间：2018-01-12 08:35

本文关键词：开裂在役钢筋混凝土梁加卸载刚度与正常使用可靠度分析　出处：《西南交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：钢筋混凝土构件被广泛应用于各种工程中,但由于混凝土的抗拉强度较低,在正常服役过程中,钢筋混凝土结构可能因为各种因素导致开裂,如构件遭受设计外过载或偶然冲击作用等。在意外荷载卸载后,由于混凝土开裂与钢筋混凝土粘结损伤的影响,构件刚度会下降,从而导致正常使用变形增大,以及正常使用可靠度降低。本文旨在于提出一种在役开裂钢筋混凝土梁正常使用可靠度的计算方法,并论证开裂损伤对钢筋混凝土梁正常使用可靠度的影响。本文报道了 11片钢筋混凝土梁的反复加卸载试验。根据实测的梁体裂缝分布形态与荷载-位移响应结果,计算了裂后钢筋混凝土梁重复加载的实测平均惯性矩。利用4片设计参数一致的钢筋混凝土梁的试验结果,验证了平均惯性矩模型在可靠度分析中的有效性。利用本文的11片梁试验数据和历史文献数据,校核了有效惯性矩模型和平均惯性矩模型的不确定性。本文利用蒙特卡罗法来考虑钢筋混凝土结构的随机性,并采用平均惯性矩模型分析了历史开裂损伤对钢筋混凝土梁的正常使用可靠度的影响,定量计算了开裂钢筋混凝土梁的短期和长期正常使用可靠度及其损失。研究结果表明,当历史荷载产生的变形可能大于变形限值时,需要考虑历史开裂损伤对短期正常使用可靠度的影响,轻度的历史损伤虽然会影响构件变形响应的概率密度,但不会影响短期正常使用可靠度。然而,在考虑收缩徐变效应时,历史开裂损伤会削弱梁体刚度,从而增大徐变和收缩的时变变形,因此即使轻度的历史损伤也会降低构件的长期正常使用可靠度。另外,钢筋混凝土梁遭受损伤荷载的时间越晚,开裂损伤对长期正常使用可靠度的影响就越小。
[Abstract]:Reinforced concrete members are widely used in various projects, but due to the low tensile strength of concrete, in the normal service process, reinforced concrete structures may cause cracking due to various factors. For example, members are subjected to design overload or accidental impact. Due to the effect of concrete cracking and bond damage of reinforced concrete, the stiffness of members will decrease after unload of accidental load, which will lead to the increase of normal service deformation. The purpose of this paper is to put forward a method to calculate the reliability of cracking reinforced concrete beams in service. The effect of cracking damage on the reliability of reinforced concrete beams in normal use is also discussed in this paper. Repeated loading and unloading tests of 11 reinforced concrete beams. According to the measured results of crack distribution and load-displacement response of beams. The measured average moment of inertia of a cracked RC beam subjected to repeated loading is calculated. The experimental results of 4 RC beams with the same design parameters are used. The validity of the mean moment of inertia model in reliability analysis is verified. The experimental data of 11 beams and historical literature data are used in this paper. The uncertainty of the effective moment of inertia model and the average moment of inertia model is checked. In this paper, the randomness of reinforced concrete structure is considered by Monte Carlo method. The average moment of inertia model is used to analyze the influence of historical cracking damage on the reliability of reinforced concrete beams. The reliability and loss of short and long term normal use of cracked reinforced concrete beams are calculated quantitatively. The results show that the deformation caused by historical loads may be greater than the deformation limit. It is necessary to consider the impact of historical cracking damage on the reliability of short-term normal use. Although mild historical damage will affect the probability density of deformation response, it will not affect the short-term reliability of normal use. When the shrinkage and creep effect is considered, the historical crack damage will weaken the stiffness of the beam, thus increasing the creep and the time-varying deformation of the shrinkage. Therefore, even mild historical damage will reduce the long-term normal use reliability of the members. In addition, the later the RC beam is subjected to the damage load, the smaller the impact of cracking damage on the long-term normal use reliability.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU375.1

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