高温后钢筋混凝土梁性能退化规律研究

【作者】 张露；

【导师】 刘小洁；

【作者基本信息】 中南大学 ， 土木工程， 2011， 硕士

【摘要】 随着经济高速发展和城市化步伐的加快,意外引起的火灾导致建筑物破坏和人员伤亡时有发生。建筑物发生火灾后,结构的力学性能如何变化一直是研究人员普遍关注的热点问题。近年来,国内外发表了许多有关高温下的混凝土与钢筋混凝土结构的研究成果,主要集中于建筑物在大火侵袭下,结构内部温度和结构挠度、内力等随时间的变化,并获得了很多有价值的研究结论。但由于火灾对建筑物的影响因素十分复杂,这些问题至今还没有得到很好的解决。本文主要做了以下的研究工作：一、通过高温后混凝土试块的抗压试验研究,得出了高温后混凝土抗压强度与受火温度、受火时间、冷却方式等影响因素的关系,并依此给出了火灾强度损失标准。二、通过高温后混凝土试块的碳化性能试验研究,得出了高温后混凝土碳化性能与受火温度、受火时间、冷却方式等影响因素的关系,为火灾后混凝土结构进行耐久性能的评估提供了指导依据。三、通过高温后RC梁的抗弯性能试验,研究了各高温影响因素对梁抗弯承载力的影响,归纳了温度裂缝和荷载裂缝的发展规律及相互关系,并验证了平截面假定的适用性。四、运用ANSYS有限元分析软件分析了不同高温工况下的温度场分布,采用等效截面缩减法计算了高温后RC梁的剩余承载力,与试验结果吻合良好。更多还原

【Abstract】 With fast economic development and rapid city growth, fire accidents may take place which results in building destruction and personal casualties. It is a topic of general interest that how the mechanic performance of the structure has changed after the building fire. Many investigations on the high temperature behavior of concrete have been reported and a lot of valuable research findings is received, which focused on the continual changes of structural temperature, deflection and interior force after exposure to fire. However, the effects of fire on building are rather complicated and still unsolved so far.In this paper, the following research works are done:(1) The relationship between compressive strength of concrete and the influence factors such as different temperature, different time and refrigeration mode is obtained based on the experiment of concrete block, and classification standards of fire is proposed.(2) The carbonation depth of concrete after high temperature is studied based on the experiment of concrete block, and the relationship between carbonation depth and the influence factors such as different temperature, different time and refrigeration mode is obtained, and the guidance to the assessment of the durability of concrete structures after fire is provided.(3) The residual load-carrying capacity of RC beams after high temperature is studied based on the experiment. The effects of influence factors to residual load-carrying capacity is researched, and the relationship and development law of temperature crack and load crack is summarized. In addition, applicability of the plane section assumption is verified.(4) The temperature field of different temperature condition is obtained based on ANSYS, a finite element analysis software. And the residual load-carrying capacity of RC beams after high temperature is calculated by equivalent cross-section reduced method, which is well coincided with the experimental results.更多还原