【作者】 顾文发；

【导师】 袁泉； 王冬雁；

【作者基本信息】 北京交通大学 ， 建筑与土木工程， 2012， 硕士

【摘要】 混凝土结构在施工中的安全性远低于其在正常使用中的安全性,我国每年都出现了多起严重的混凝土结构坍塌事故,造成了重大人员伤亡和严重不良的社会影响。由于在结构设计中一般只考虑混凝土设计强度指标,而施工中的混凝土材料力学性能远达不到设计强度的各项指标,并且不断发生改变,这种变化对施工中结构的安全性及使用期结构的安全性、耐久性均有重大影响,是施工中结构发生倒塌的重要原因之一。研究混凝土早龄期的力学性能及变化规律有重要的理论意义与工程应用价值。本文以C40商品混凝土材料早龄期试验为基础,研究其力学性能及其变化规律,本文的主要工作如下：(1)混凝土抗压试验：通过对7个不同龄期的45块试件进行抗压强度试验,得出C40商品混凝土抗压强度随龄期的变化规律；并结合前人进行的试验给出早龄期混凝土强度指标设计方法；根据规范结合试验数据给出3d推定28d强度的拟合公式。(2)混凝土劈裂试验：通过对7个不同龄期的24块试件进行劈裂试验,得出劈拉强度随龄期发展规律；并对劈拉强度与立方体抗压强度换算给出建议公式。(3)混凝土弹性模量试验：通过对6个不同龄期的21块试件进行静弹模试验,得出C40商品混凝土弹性模量随龄期的变化规律；并通过试验数据拟合给出弹性模量与立方体抗压强度的建议换算公式。(4)应力应变全曲线试验：通过对3个不同龄期的9块试件进行单轴受压试验,绘出各龄期试件的应力应变曲线；通过推导与分析,得出C40商品混凝土各龄期的单轴受压本构方程。通过对C40商品混凝土早龄期力学性能试验研究及分析,建立了其抗压强度、劈拉强度、弹性模量及单轴应力应变全曲线的计算公式,并初步得出其力学性能随龄期增长的变化规律,为后期研究混凝土早龄期构件和结构的定量计算与分析提供基础。更多还原

【Abstract】 The safety of concrete structure in construction is far below it in normal use, every year there have been numerous serious collapse accidents of concrete structures, causing major casualties and severe adverse social effects. The reason of the above facts is that the material mechanical properties of concrete in construction is ever-changing, which have a significant impact on security and durability of structures in construction and usage period. Study on variation of mechanical properties of concrete at early age has important theoretical significance and application value. This paper research on the mechanical properties and its changes on the basis of C40commodity concrete early age test. The main works of this paper are as follows:(1) Compression test of concrete:come to the law of development of compressive strength with age of C40commodity concrete by compressive strength tests of45test blocks in7different ages; And give the proposal removal time based on predecessors’ tests; And give a28d strength fitting formula draw out from3d according to the specifications with test data.(2) Split test of Concrete: come to the law of development of splitting tensile strength with age by split tests of24test blocks in7different ages. And gives recommended formula of splitting tensile strength and cubic compressive strength.(3) Elastic modulus test of concrete:come to the law of development of elastic modulus with age of C40commodity concrete by elastic modulus tests of21test blocks in6different ages; And gives advice conversion formulas of elastic modulus and cubic compressive strength.(4) Stress-strain curves experiment:maps the stress-strain curves of test blocks in different ages by uniaxial compression tests of9test blocks in3different ages. By derivation and analysis, come to the uniaxial compressive stress-strain equation of C40commercial concrete.Established the calculation formula of compressive strength splitting tensile strength、elastic modulus and uniaxial stress-strain curves through the experimental study and analysis on mechanical properties of C40commercial concrete at early age, and initially concluded the growth of mechanical properties with age, which provide a basis for quantitative calculation and analysis of structure and concrete members at early age.更多还原