火灾后混凝土梁斜截面抗剪性能研究

发布时间：2018-11-23 17:28

【摘要】：近几年混凝土桥梁火灾事故逐渐增多,火灾产生的高温对混凝土梁造成不同程度的损伤,影响梁体的承载能力和正常使用。受火后混凝土梁承载能力评定是灾后桥梁损伤评定和维修加固的重要依据。本文针对火灾后混凝土梁抗剪性能进行研究,具体工作如下:(1)归纳总结了火灾后混凝土桥梁构件的损伤特征,并建议了适用于桥梁受火后的初步损伤评定和详细评定的标准。(2)进行了混凝土、普通钢筋的高温试验及力学性能试验,得到了材料在高温不同方式冷却后的强度衰减规律。(3)进行了高温环境下混凝土内部温度分布的试验。通过数据处理,研究了混凝土内部温度分布规律。运用ANSYS有限元软件数值模拟混凝土温度场试验,并与试验数据对比。实验数据与模拟计算结果吻合良好。(4)基于我国现行的“建工规范”、“公路规范”、“铁路规范”中混凝土梁抗剪承载力的计算公式以及“桁架-拱”受剪计算模型,提出了火灾高温后混凝土梁抗剪强度的折减方法,并与相关试验梁结果进行了对比分析。(5)对某受火实桥进行了案例研究,得到其在火灾后抗剪性能衰减情况,并对其进行损伤评定。
[Abstract]:In recent years, the fire accidents of concrete bridges have increased gradually, and the high temperature caused by the fire has caused varying degrees of damage to concrete beams, which affects the bearing capacity and normal use of the beams. The evaluation of bearing capacity of concrete beams after fire is an important basis for damage assessment and maintenance and reinforcement of bridges after disaster. In this paper, the shear behavior of concrete beams after fire is studied. The specific work is as follows: (1) the damage characteristics of concrete bridge members after fire are summarized. At the same time, it suggests the standard for the initial damage assessment and detailed evaluation of bridges after fire. (2) the high temperature test and mechanical property test of concrete and ordinary steel bar are carried out. The strength attenuation law of the material after cooling in different ways at high temperature is obtained. (3) the temperature distribution of concrete in high temperature environment is tested. Through data processing, the temperature distribution in concrete is studied. The ANSYS finite element software is used to simulate the temperature field test of concrete, and the results are compared with the test data. The experimental data are in good agreement with the simulation results. (4) based on the calculation formula of shear capacity of concrete beams and the calculation model of "truss-arch" shear capacity in China's current "Construction Code", "Highway Code", "Railway Code", In this paper, a reduction method of shear strength of concrete beams after fire is put forward, and the results are compared with those of experimental beams. (5) A case study is carried out on a real bridge under fire, and the attenuation of its shear resistance after fire is obtained. The damage was evaluated.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U441

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