混凝土砌块砌体通缝剪切性能试验研究

发布时间：2018-05-05 15:38

本文选题：砌块砌体 + 通缝抗剪强度　；参考：《哈尔滨工业大学》2016年硕士论文

【摘要】：砌体结构在全世界拥有悠久的历史,为人类繁衍和文化传承作出了重要贡献。但传统无筋砌体的脆性特征和抗拉、抗剪强度不足的现实,特别是地震作用下砌体易倒塌、延性不足的表现,严重制约了砌体结构的发展。本文以村镇低层砌体房屋产业化项目为背景,依照标准试验方法对混凝土砌块砌体通缝剪切作用下的基本力学性能进行试验研究,为规范修订和工程应用提供技术支撑。课题进行了24组共36个空心及36个灌芯混凝土砌块砌体标准件的通缝剪切试验,研究了砌筑砂浆强度、灌芯混凝土强度、加载方式及轴向压力对砌体抗剪性能的影响,获取了标准件的破坏状态、抗剪强度、开裂强度、峰值位移等基本力学性能参数,并获得了较为理想的荷载-位移曲线。课题同时进行了8组共15个空心及9个灌芯砌体标准件的抗压试验,获得了抗压强度、弹性模量、泊松比等力学性能参数。试验结果表明:空心砌块砌体弹性模量的试验值高于现行规范的计算值;基于抗压试验结果计算得到的砌体剪变模量与通缝剪切试验结果吻合较好;不同的加载方式对砌体抗剪强度有明显影响;轴向压力的施加提高了砌体的抗剪强度、峰值位移,改善了砌体的延性;灌芯砌体在剪切荷载作用下,砂浆层与灌芯混凝土存在协同工作的位移差,即在达到峰值荷载前砂浆层已出现贯通裂缝退出工作,后期抗剪强度主要由灌芯混凝土提供,既有灌芯砌体规范给出的抗剪强度公式在充分考虑砂浆强度贡献后计算结果偏向于不安全;灌芯砌体开裂前刚度较大,开裂后则出现明显的刚度衰减,其开裂强度与砂浆强度、灌芯混凝土强度、轴向压力大小均呈正相关关系。基于本文试验数据和既有研究成果的统计分析,拟合得到了考虑孔洞率的混凝土实心砖、多孔砖、空心砌块的砌体抗剪强度的计算公式;现行砌体规范中剪压复合作用下的摩擦系数取值对于低轴压比下的空心砌块砌体偏于保守,本文给出了建议取值;轴向压力对灌芯砌体标准件和墙体抗剪承载力影响的差异性较大。本文基于试验数据的统计分析,建立了预压力空心及灌芯砌体的残余抗剪强度系数表达式,所拟合得到的无量纲荷载-位移曲线分段表达式与预压力空心、灌芯及预压力灌芯砌体通缝受剪时的变形性能吻合较好。
[Abstract]:Masonry structure has a long history in the world, and has made important contributions to human reproduction and cultural heritage. However, the brittleness of traditional unreinforced masonry and the reality of insufficient tensile strength and shear strength, especially the weak ductility and collapse of masonry subjected to earthquake, seriously restrict the development of masonry structure. Based on the industrialization project of village and town low story masonry building, the basic mechanical properties of concrete block masonry under shear action are studied according to the standard test method, which provides technical support for standard revision and engineering application. In this paper, 24 groups of 36 hollow and 36 concrete block masonry standard parts were tested, and the effects of masonry mortar strength, core concrete strength, loading mode and axial pressure on the shear properties of masonry were studied. The failure state, shear strength, cracking strength and peak displacement of the standard parts are obtained, and the ideal load-displacement curves are obtained. At the same time, eight groups of 15 hollow masonry and 9 core masonry standard parts were tested, and the mechanical properties such as compressive strength, elastic modulus and Poisson's ratio were obtained. The experimental results show that the experimental value of elastic modulus of hollow block masonry is higher than that of current code, and the shear modulus of hollow block masonry is in good agreement with the shear test result of through joint. Different loading modes have obvious influence on the shear strength of masonry, the application of axial pressure increases the shear strength and peak displacement of masonry, and improves the ductility of masonry. There is a difference in displacement between mortar layer and pouring concrete, that is, before the peak load is reached, there is a through crack exiting in the mortar layer, and the shear strength in the later stage is mainly provided by the core pouring concrete. The calculation results of the shear strength formula given by the existing code for cast-in-place masonry with full consideration of the contribution of mortar strength tend to be unsafe, and the stiffness of the masonry is larger before cracking, and there is obvious stiffness attenuation after cracking, and the cracking strength and mortar strength are obvious. The strength and axial pressure of concrete are positively correlated. Based on the experimental data of this paper and the statistical analysis of the existing research results, the formulas for calculating the shear strength of concrete solid brick, porous brick and hollow block are obtained by fitting. In the current masonry code, the friction coefficient of hollow block masonry under shear-compression combination is conservative for the hollow block masonry with low axial compression ratio, and the suggested values are given in this paper. The influence of axial pressure on the shear bearing capacity of standard masonry and wall is quite different. Based on the statistical analysis of test data, the expressions of residual shear strength coefficients of pre-pressure hollow masonry and grouted masonry are established in this paper. The dimensionless load-displacement curve segment expression and pre-pressure hollow section expression are obtained. The deformation behavior of masonry joints under shearing is in good agreement with that of prepressurized masonry.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU522.3

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