【作者】 杜朝华；

【导师】 刘立新；

【作者基本信息】 郑州大学 ， 结构工程， 2012， 博士

【摘要】 随着经济的高速腾飞和城市化进程的发展,我国的建造事业也得到蓬勃发展,新建工程结构的施工、旧有混凝土建筑物的拆除以及各种灾害的发生,都会产生大量的废弃混凝土建筑垃圾,造成环境污染。再生混凝土可以解决上述问题的变废为宝、缓解城市环境的压力、节约资源而得到推广使用,因此,建筑垃圾再生混凝土及其结构成为国内外的研究热点。本文通过试验,系统研究了再生混凝土的基本力学性能、钢筋再生混凝土梁的受弯性能、钢筋再生混凝土梁的受剪性能和钢筋再生混凝土柱的受压性能,利用有限元数值分析方法,采用本文提出的再生混凝土本构关系,对再生混凝土构件的受力性能进行了进一步的研究。主要研究内容如下：1.再生混凝土基本力学性能试验研究通过对替代率分别为0%、30%、50%、70%和100%的再生骨料混凝土试件的基本力学性能试验,分析了再生骨料混凝土在3d、7d、14d、28d和60d龄期下的立方体抗压强度、轴心抗压强度、劈裂抗拉强度,研究了再生混凝土的应力-应变全曲线、弹性模量以及自然养护条件下收缩变形的特点。结果表明,在水泥、粗细骨料用量相同条件下,再生混凝土的立方体抗压强度随替代率的增大呈线性降低；当再生混凝土和普通混凝土的强度等级相同时,再生混凝土的轴心抗压强度随替代率的增大略有增大,而再生混凝土的抗拉强度和弹性模量则随替代率的增大而降低,大致成线性关系；收缩变形随替代率的增大而增大。建立了再生混凝土立方体抗压强度、轴心抗压强度、抗拉强度、弹性模量和收缩应变随替代率变化与普通混凝土相应指标间的关系式。在试验研究的基础上,建议了供工程应用的不同替代率再生混凝土基本力学性能指标。2.钢筋再生混凝土梁受弯性能试验研究通过对混凝土强度等级为C30和C40、替代率分别为0%、50%和70%的6根钢筋再生骨料混凝土梁的受弯性能试验,比较了钢筋再生骨料混凝土梁与普通钢筋混凝土梁受弯性能的异同,分析了钢筋再生骨料混凝土梁的开裂弯矩、极限弯矩、挠度和裂缝发展的规律。建议采用考虑替代率影响的再生混凝土抗压强度、抗拉强度和弹性模量以后,钢筋再生骨料混凝土梁的极限弯矩、开裂弯矩、裂缝宽度和挠度可按现行混凝土结构设计规范的相应公式计算,计算值与试验结果符合良好。3.钢筋再生混凝土梁受剪性能试验研究通过对混凝土强度等级为C30、替代率分别为0%、50%和170%的9根不同剪跨比钢筋再生骨料混凝土梁的受剪性能试验,比较了钢筋再生骨料混凝土梁与普通钢筋混凝土梁受剪性能的异同点,分析了钢筋再生骨料混凝土梁的受剪破坏形态,影响斜截面受剪承载力的主要因素,以及斜裂缝发展的特点。指出采用考虑替代率影响的再生混凝土力学性能指标后,钢筋再生混凝土梁的受剪承载力仍可按现行规范相关的公式计算。4.钢筋再生混凝土柱受压性能试验研究通过对替代率分别为0%、50%和70%的12根钢筋再生混凝土柱的轴心受压以及偏心率分别为0.343,0.537和0.800的偏心受压试验,分析了钢筋再生混凝土受压构件的受力特点和破坏形态,以及影响受压承载力的主要因素。指出采用考虑替代率影响的再生混凝土力学性能指标后,钢筋再生混凝土构件的受压承载力仍可按现行规范相关的公式计算。5.钢筋再生混凝土梁、柱受力性能的数值分析引入再生混凝土基本力学性能试验研究中得出的再生混凝土力学性能指标和应力-应变关系,利用大型有限元程序对钢筋再生混凝土梁的受弯和受剪性能、钢筋再生混凝土柱的受压性能进行了数值分析,并与试验结果进行对比,数值分析结果与试验结果符合良好,进一步验证了本文提出的再生混凝土力学性能指标和应力-应变关系的适用性。本文的研究成果为建筑垃圾再生骨料混凝土的工程应用提供了参考依据。更多还原

【Abstract】 With the rapid economic development and high speed urbanization process, the construction industry has gained significant achievement. A lot of wastes of building are produced in the process of construction, structure demolition and after disasters, which can cause environmental pollution. However, the use of recycled concrete, which is researched by many countries, can minimize negative environmental impact in the city and slow the huge consumption of natural resources. The material properties of recycled aggregate concrete, the flexural behavior of recycled concrete beam, the shearing behavior of recycled concrete beam, and the compression behavior of column are studied in the paper with the method of test. The behavior of recycled concrete members are researched with the finite element method at the last of this paper on the basis of constitutive relation of recycled concrete. The research work of this thesis is shown as following:1. Experimental study on mechanical properties of recycled concreteBy the means of test on different replacement percentages of recycled aggregate concrete(ie,0%,30%,50%,70% and 100%).the workability of recycled concrete, the cubic compressive strength of different age(ie,3d,7d,14d,28d and 60d),axial compressive strength, splitting tensile strength, the relationship between stress and strain,elastic modulus and the characteristics of shrinkage deformation under natural curing are analyzed and discussed. Under the same condition with same cement content and same fine aggregate content, the cubic compressive strength of recycled concrete decreased in approximate linearity with the increase of replacement percentages.Under the same strength grade, the axial compressive strength increase slowly with the increase of replacement percentages, while the tensile strength and elastic modulus decrease in approximate linearity with the increase of replacement percentages. Meanwhile, the shrinkage deformation increase with the increase of replacement percentages. The relational formula between cubic compressive strength, axial compressive strength, tensile strength, elastic modulus, shrinkage strain and replacement percentages,corresponding property index of common concrete are built. Basis on the test results, the mechanical property index of recycled concrete with different replacement percentage which has a significant engineering value.2. Experimental study on flexural behavior of recycled concrete beamOn the basis of testing on 6 beams with different concrete strength grade(ie.C30 and C40) and different replacement percentage(ie.0%,50% and 70%),the similarities and difference between common concrete beams and recycled concrete beams are compared. The ultimate moments, deflection, cracking moment and the rule of crack development of recycled concrete beam are analyzed. Based on the mechanical property index of recycled concrete, it is proved that it is feasible to apply the current design standard for ultimate bearing capacity, cracking moment, crack width and deflection of recycled concrete beams, which gives higher calculation accuracy.3. Experimental study on shearing behavior of recycled concrete beamOn the basis of testing on 9 beams for grade C30 with different shear span ratio(ie.1.5,2.5 and 3.0) and different replacement percentage(ie.0%,50% and 70%),the similarities and difference of shearing behavior between common concrete beams and recycled concrete beams are compared. The failure patterns, the main influencing factors of shear capacity and the characteristics of development of cracks are analyzed and discussed. Based on the mechanical property index of recycled concrete, it is proved that it is feasible to apply the current design standard for shear capacity of recycled concrete beams, which gives higher calculation accuracy.4. Experimental study on compression behavior of recycled concrete columnOn the basis of testing on 12 columns with different eccentricity ratio(ie.0,0.343,0.537 and 0.800)and different replacement percentage(ie.0%,50% and 70%),the loading feature, the failure patterns and the main influencing factors of compression capacity are analyzed and discussed. Based on the mechanical property index of recycled concrete, it is proved that it is feasible to apply the current design standard for compression capacity of recycled concrete columns, which gives higher calculation accuracy.5. Numerical analysis of loading behavior of recycled concrete beam and columnWith the nonlinear finite element program ANSYS, the numerical simulation on flexural behavior of beams, shearing behavior of beams and compression behavior of columns are presented, and the mechanical property index and constitution relation of recycled concrete which have been obtained in this paper are introduced into the finite element model. The calculating results agree well with test ones by the comparison between those results, which indicate that the mechanical property index and constitution relation of recycled concrete are reasonable and correct.The research results of this paper provide reference for engineering application of recycled aggregate concrete.更多还原