基于早龄期加载的PVA纤维超高强混凝土长期荷载作用下的徐变性能研究

发布时间：2018-04-17 20:51

本文选题：超高强混凝土 + 基于早龄期加载　；参考：《深圳大学》2017年硕士论文

【摘要】：每个时代都会有一些代表性的建筑物横空出现,随着科技的不断发展与更新,超级工程即将成为新世纪具有代表性的符号,这些超级工程包括摩天工程、桥梁工程、水利工程、海洋工程等。它们对混凝土性能的要求越来越高,在此背景下,高强以及超高强混凝土的研究和应用逐渐成为主流的研究方向,在超级工程中扮演者重要的角色。高强混凝土的耐久性相对于普通强度混凝土更具有优越性,工程中出现的一些质量问题的出现一般是由于耐久性降低的缘故。混凝土徐变一般是导致工程耐久性破坏的原因之一。现阶段面向超高强混凝土领域研究尤其是对基于早龄期加载的混凝土徐变性能的研究资料更是缺乏。本文主要是面向早龄期加载的超高强混凝土的徐变性能进行相关的研究,设置了C80、C100、C120三种等级的超高强混凝土;根据工程中常见的未待混凝土成熟硬化即开始加载施工的实际情况,基于混凝土龄期,设置了以3天、7天、14天作为加载龄期,同时又设置了体积掺量分别为0.0%、0.25%、0.5%、1.0%的PVA纤维来综合研究早龄期加载的PVA纤维超高强混凝土长期荷载作用下的徐变性能。本文主要根据相关的研究资料介绍了混凝土的徐变机理以及相关的影响因素,同时又分析了国内外常见的徐变预测模型,并对它们各自的适用范围以及考虑因素做了对比介绍。这为分析超强混凝土的徐变特性与提出适用于PVA纤维超高强混凝土的徐变预测模型奠定了理论基础。基于试验研究,结合B3变异系数法,评选出了ACI209(92)徐变预测模型为修正研究的对象。本文研究了混凝土的强度对徐变发展速率影响,基于ACI209(92)徐变预测模型提出了强度修正因子。基于PVA纤维在混凝土徐变中的阻裂机理与改善效果的进行了定性定量分析的研究。基于混凝土裂缝产生的机理,分析了PVA纤维在混凝土徐变中的阻裂机理,并进行了定性定量的研究分析。最后依据原ACI209(92)徐变预测模型中塌落度影响系数提出了PVA纤维混凝土塌落度综合影响系数,将PVA纤维混凝土未加载前的塌落度影响系数与加载后在持荷周期内的徐变系数的影响进行了有效的结合,这也是本文研究的创新点之一。同时根据早龄期加载对徐变影响的研究,补充了混凝土强度对加载龄期基准影响系数的影响修正系数。结合所有的研究,最终提出了基于早龄期加载的PVA纤维超高强混凝土的徐变预测修正模型。
[Abstract]:Each time there will be some typical buildings turned occur, with the development of science and technology, super engineering will become the representative of the new century symbol, these super engineering including Ferris engineering, bridge engineering, hydraulic engineering, marine engineering and so on. They are on the concrete performance of the increasingly high demand, in this context, the research and application of high strength and super high strength concrete has gradually become the main research direction, play an important role in super engineering. The durability of high strength concrete with ordinary strength concrete has more advantages, some quality problems appearing in engineering is generally due to lower durability because of concrete creep is one of the leading general. The reason of Engineering durability damage. At the present stage for super high strength concrete research field especially for concrete early age loading based on Xu Bianxing The research data is lacking. This paper is mainly related to research on creep properties for early age loading of ultra high strength concrete, set up C80, C100, C120 three grades of super high strength concrete; according to the engineering of the common concrete hardening is not to be mature the actual situation of construction loading, concrete age based on the 3 day, 7 day, 14 days as a loading age, and set the volume fraction is 0%, respectively, 0.25%, 0.5%, 1% PVA fiber PVA fiber to comprehensive research on the early age loading of ultra high strength concrete under long-term load creep performance. This paper mainly according to the relevant research data introduces the factors of concrete creep mechanism and related effects, and also analyzed the domestic and foreign common creep prediction models, and their respective scope of application and consideration. It is introduced to do a comparative analysis of super The creep characteristics of the concrete and applied to PVA fiber super high strength concrete creep prediction model has laid a theoretical foundation. Based on the test results, combined with the B3 coefficient of variation method, the selection of the ACI209 (92) creep prediction model for the modification of the object. This paper studies the effect of concrete strength on the creep rate of development, based on the ACI209 (92) creep prediction model proposed for the strength correction factor of PVA fiber in concrete creep mechanism and improve the anti crack effect is studied. Based on the qualitative and quantitative analysis of the mechanism of concrete crack based on the analysis of cracking mechanism of PVA fiber in the concrete creep resistance, and the qualitative and quantitative analysis of the final. The original ACI209 (92) creep prediction collapsbillity influence coefficient are proposed in the model of PVA fiber concrete collapsbillity comprehensive effect coefficient, the PVA fiber concrete slump is not loaded before The influence coefficient and loading after impact load to creep coefficient period are combined effectively, which is also one of the innovation of this paper. At the same time according to the influence of the early age loading on creep, supplement the strength of concrete loading age benchmark affecting coefficient correction coefficient. Combining all the research, finally the creep of early age loading of PVA fiber reinforced ultra high strength concrete prediction model based on the correction.

【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528.572

【相似文献】