高性能混凝土高温热变形试验及热应力模拟研究

发布时间：2018-01-29 18:03

本文关键词： 高性能混凝土高温聚丙烯纤维热应变 ABAQUS模拟　出处：《太原理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：高性能混凝土因其具备良好的综合性能已被普遍应用于各项土木工程中。然而,高性能混凝土因其高密实性低渗透性,当其遭受火灾高温时,由于内部产生的蒸汽压、热变形及温度应力等多因素综合作用,易导致混凝土发生爆裂、脱落、承载力降低甚至坍塌,建筑物的安全性及人们生命财产将受到威胁,因此研究高性能混凝土高温性能,揭示其内部应力及宏观承载力随温度变化的损伤规律,具有重要的理论意义和工程价值。依托国家自然基金(51478290),以C60高性能混凝土为对象,研究高温对其力学性能的影响;借助热电偶和正弦应变计研究高温与混凝土板内部的温度场及热应变的关系;借助ABAQUS软件对高性能混凝土板高温下内部热应力和裂缝的发展以及构件的变形进行探索性模拟研究,主要内容如下。一、高性能混凝土宏观力学试验,研究不掺与掺0.2%聚丙烯纤维的高性能混凝土高温后的劈裂抗拉强度,轴心抗压强度及弹性模量,试验结果表明各项力学性能指标总体随温度升高而降低,但掺纤维混凝土的劣化程度要明显比素混凝土低,并依托试验结果建立了混凝土的各项指标与受热温度的曲线。二、高性能混凝土高温热变形试验,研究聚丙烯纤维掺量为0%、0.1%、0.2%、0.3%的混凝土板,在其中不同深度埋入混凝土正弦应变计和高温热电偶,并且在其中布置了单层钢筋网,通过高温电阻炉将混凝板土进行加热,试验结果表明热应变总体上随温度的升高而升高,掺纤维混凝土板的热应变要低于不掺纤维的混凝土板,并且热应变随着纤维掺量的增加而逐渐减小,钢筋网深度附近的热应变要明显低于其他位置。三、明火与荷载耦合下的高温热变形试验,研究聚丙烯纤维掺量为0%、0.2%的混凝土大板,与混凝土小板相同在其中布置了单层钢筋网和正弦应变计,并且通过计算后在混凝土板上施加了相应的荷载,将混凝土大板通过明火进行加热,试验结果表明热应变总体上随着温度的升高而升高,上升速率高明显高于在高温电阻炉里加热的情况。四、高性能混凝土板热应力探索性模拟研究,通过ABAQUS模拟软件初步分析了掺0.2%聚丙烯纤维的混凝土板高温热应变的发展情况,为了与实际工程结合地更紧密,选取了较大尺寸的混凝土板进行探索性模拟。由于模型未考虑混凝土应该含有的孔隙、含水量、非均质等特性,因此模拟结果与实际结果有一些误差,结果表明在混凝土板厚度方向形成了温度梯度,模拟结果与试验结果对比分析发现在同一深度处温度和热应力随时间的变化趋势基本一致。
[Abstract]:High performance concrete (HPC) has been widely used in civil engineering because of its good comprehensive performance. However, high performance concrete (HPC) suffers from high fire temperature because of its high density and low permeability. Because of the internal steam pressure, thermal deformation and temperature stress and other factors, it is easy to cause the concrete burst, fall off, reduce or even collapse of the bearing capacity. The safety of buildings and the life and property of people will be threatened, so the high temperature performance of high performance concrete is studied, and the damage law of internal stress and macroscopic bearing capacity with temperature is revealed. It is of great theoretical significance and engineering value. Based on the National Natural Fund 51478290, the influence of high temperature on mechanical properties of C60 high performance concrete is studied. The relationship between high temperature and temperature field and thermal strain of concrete slab is studied by means of thermocouple and sine strain gauge. With the help of ABAQUS software, the development of internal thermal stress and crack and the deformation of members of high performance concrete slab at high temperature are studied. The main contents are as follows. The splitting tensile strength, axial compressive strength and elastic modulus of high performance concrete without or without 0.2% polypropylene fiber at high temperature were studied. The results show that the mechanical properties of concrete decrease with the increase of temperature, but the deterioration of fiber reinforced concrete is obviously lower than that of plain concrete. Based on the test results, the curves of concrete indexes and heating temperature are established. Secondly, the high performance concrete hot deformation test at high temperature, the content of polypropylene fiber is 0. 1% and 0. 2%. 0.3% concrete slabs are embedded in concrete sinusoidal strain gauges and high-temperature thermocouples at different depths, and a single-layer steel mesh is arranged in the concrete slabs, which are heated by high temperature resistance furnace. The results show that the thermal strain increases with the increase of temperature, and the thermal strain of fiber reinforced concrete slab is lower than that of concrete slab without fiber, and the thermal strain decreases with the increase of fiber content. The thermal strain near the depth of steel mesh is obviously lower than that in other places. Thirdly, under the coupling of open fire and load, the high temperature thermal deformation test is carried out to study the large concrete slab with polypropylene fiber content of 0.2%. In the same way as the concrete slabs, single-layer steel mesh and sinusoidal strain gauges are arranged in them, and the corresponding loads are applied to the concrete slabs after calculation, and the large concrete slabs are heated through open fire. The experimental results show that the thermal strain generally increases with the increase of temperature, and the rising rate is obviously higher than that of heating in high temperature resistance furnace. Fourthly, the exploratory simulation study on thermal stress of high performance concrete slabs. The development of high temperature thermal strain of concrete slab doped with 0.2% polypropylene fiber was analyzed by ABAQUS simulation software, in order to be more closely combined with practical engineering. Large size concrete slabs are selected for exploratory simulation. Because the model does not consider the pore, water content, heterogeneity and other characteristics of concrete, there are some errors between the simulation results and the actual results. The results show that the temperature gradient is formed in the direction of concrete slab thickness, and the comparison between the simulation results and the experimental results shows that the variation trend of temperature and thermal stress with time is basically the same at the same depth.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

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