火灾高温后再生混凝土受压应力—应变曲线及其与钢筋的粘结性能试验研究

发布时间：2018-04-22 09:37

本文选题：火灾高温 + 再生混凝土　；参考：《广西大学》2015年硕士论文

【摘要】：近年来,由于人口的高度集中、建筑火灾事故的频发,给人民的生命和财产带来了严重损失。另一方面,伴随着世界范围内大量建筑垃圾处理问题的亟待解决以及建筑材料的巨大损耗和短缺,再生混凝土应用于建筑结构工程成为趋势。因此,在再生混凝广泛推广应用于结构工程之前,有必要对于再生混凝土以及钢筋再生混凝土受火灾高温后的相关力学性能进行研究。本文主要通过试验手段,结合相关理论分析,针对再生混凝土受高温作用后的受压应力一应变关系以及钢筋再生混凝土受高温作用后的粘结滑移性能进行研究。完成的工作有：一、对经过不同温度作用后的天然混凝土和再生混凝土,采用超景深三维显微系统对比观察其受压破坏后微观裂缝的开展状态,了解各个界面的粘结情况。二、通过对同强度再生混凝土受高温作用后的单轴受压试验,研究了在不同再生粗骨料取代率和不同温度条件下再生混凝土的应力和应变的特点,并根据试验结果建立了再生混凝土受高温作用后的应力—应变全曲线方程。三、通过中心拉拔试验研究了高温后钢筋与再生混凝土间的粘结滑移性能,揭示了在不同温度条件、不同再生粗骨料取代率、不同相对保护层厚度c/d和有无横向约束箍筋等条件影响下的粘结滑移性能,获得了相应的粘结—滑移曲线。四、依据损伤力学应变等效性假设的相关理论知识分析了高温后钢筋与再生混凝土间的粘结滑移性能,定义粘结损伤变量D,计算得到损伤演变方程D-s关系曲线,建立了基于界面损伤的粘结—滑移本构方程。主要研究结论如下：(1)采用三维显微系统观察和分析表明,在经历不同温度作用后,天然混凝土破坏时内部的薄弱面为骨料—砂浆界面；再生混凝土受压破坏时内部各个界面相对薄弱程度从重到轻依次为：旧骨料—新砂浆界面、旧砂浆—新砂浆界面和旧骨料—旧砂浆界面。(2)同一取代率条件下,受高温作用后的再生混凝土试件的峰值应力呈减小趋势,峰值应变呈增大趋势,且所经历的温度越高,峰值应力越小,峰值应变越大,峰值应力最大损失为53.8%，峰值应变最大增幅为270.1%。(3)当试件经历温度小于或等于400℃,在同一温度下,随着粗骨料取代率的增大,再生混凝土峰值应力呈减小趋势,峰值应变呈增大趋势；当试件经历温度达到500。C后,出现了相反的规律,在同一温度下,随着取代率的增加,再生混凝土峰值应力整体呈增大趋势,而峰值应变呈减小趋势。(4)在同一高温条件作用后,取代率为100%的再生混凝土的峰值应力均大于其他各取代率的结果,而峰值应变则小于其他各取代率的峰值应变。(5)不带箍筋试件的主要破坏模式为劈裂破坏,带箍筋试件的主要破坏模式为劈裂—拔出破坏。(6)同一取代率条件下,试件经历的温度越高,试件峰值粘结应力越小,峰值滑移量越大,温度达500℃时,峰值粘结应力最大损失为66.2%,峰值滑移值最大增幅为126.4%。同时,带箍筋试件的平均峰值粘结应力和平均峰值滑移值均要大于不带箍筋试件的结果；相对保护侧厚度c/d越大,则峰值粘结应力越大,峰值滑移值也越大。(7)当温度在小于或等于400℃时,每个温度条件下均有一个最优粗骨料取代率对抵抗试件的粘结滑移破坏最有利,而当温度达到500℃后,则是再生粗骨料取代率越大,对抵抗粘结滑移破坏越有利。
[Abstract]:In recent years, because of the high concentration of the population, the frequent occurrence of building fire accidents has brought serious loss to the people's life and property. On the other hand, with the problem of building garbage disposal in the world and the huge loss and shortage of building materials, the application of re concrete to the construction engineering has become a trend. Therefore, it is necessary to study the related mechanical properties of recycled concrete and regenerated concrete after fire and high temperature. This paper mainly deals with the stress-strain relationship of regenerated concrete under the effect of high temperature, and it is necessary to study the related mechanical properties of recycled concrete and regenerated concrete after fire and high temperature. The bond slip behavior of rebar regenerated concrete is studied by high temperature action. The work completed is: first, the natural concrete and recycled concrete after different temperatures are used, and the development state of the micro cracks after the compression failure is compared with the three dimensional microscopic system of ultra depth of field, and the bonding condition of each interface is understood. Two The stress and strain characteristics of recycled concrete under different recycled coarse aggregate and different temperature are studied after the uniaxial compression test of the same strength recycled concrete subjected to high temperature. According to the test results, the stress strain full curve equation of recycled concrete under high temperature is established. Three, through the central drawing The bond slip behavior between reinforced concrete and regenerated concrete after high temperature is studied. The bond slip curves are obtained under the influence of different temperature conditions, the substitution rate of recycled coarse aggregate, the thickness c/d of different relative protective layer and the transverse confinement stirrup. Four, according to the mechanics of damage. The related theoretical knowledge of the variable equivalence hypothesis is used to analyze the bond slip behavior between steel and recycled concrete after high temperature. The bond damage variable D is defined, and the D-s relation curve of the damage evolution equation is calculated. The bond slip constitutive equation based on the interface damage is established. The main conclusions are as follows: (1) the three-dimensional microscopic system observation and the analysis are as follows. The analysis shows that the internal weak surface is the aggregate mortar interface when the natural concrete is damaged by different temperatures, and the relative weak degree of the internal interfaces of the recycled concrete is in turn, the old aggregate - the new mortar interface, the old mortar - the new mortar interface and the old aggregate - the old mortar interface. (2) the same one. Under the condition of substitution, the peak stress of recycled concrete specimen after high temperature is decreased, and the peak strain is higher, the higher the peak stress, the greater the peak strain, the maximum peak stress loss 53.8%, the maximum strain of the peak strain 270.1%. (3), when the temperature is less than or equal to 400 C. At the same temperature, with the increase of the replacement rate of coarse aggregate, the peak stress of recycled concrete decreases and the peak strain shows an increasing trend. When the temperature reaches 500.C, the reverse regularity appears. At the same temperature, with the increase of the substitution rate, the peak stress of the regenerated concrete increases, and the peak strain shows the trend. (4) after the same high temperature condition, the peak stress of the recycled concrete with the substitution rate of 100% is greater than that of the other substitution rates, while the peak strain is less than the peak strain of other substitutional rates. (5) the main failure mode of the specimen without stirrups is splitting failure, and the main failure mode with the stirrup specimen is splitting. (6) under the same substitution rate, the higher the temperature of the specimen is, the smaller the peak bond stress is, the greater the peak slip, the maximum loss of the peak bond stress is 66.2%, the maximum peak slip value is 126.4%., and the average peak bond stress and the average peak slip value of the test pieces with stirrup are both large. The greater the relative protective side c/d, the larger the relative protective side thickness, the greater the peak bond stress, and the greater the value of the peak slip. (7) when the temperature is less than or equal to 400 C, there is an optimal coarse aggregate substitution rate under each temperature condition to resist the bond slip failure of the specimen, while the temperature reaches 500 degrees C. The greater the replacement rate of raw coarse aggregate is, the more favorable it is to resist bond slip failure.

【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU398.9;TU352.5

【参考文献】