无粘结预应力RPC梁疲劳性能试验及理论研究

发布时间：2018-06-11 14:53

本文选题：无粘结预应力RPC梁 + 开裂荷载　；参考：《湖南科技大学》2017年硕士论文

【摘要】：活性粉末混凝土(Reactive Powder Concrete,以下简称RPC)以其具有的优异性能逐渐受到研究人员的青睐。国内外学者对其材料的配合比构件的静力性能耐腐蚀性能等进行了研究,但对其构件疲劳性能的研究还是很少涉及。而实际生活中构件在大多数情况下都可能承受疲劳荷载。同时由于活性粉末混凝土构件的截面应力分布及破坏形式不同于普通混凝土。出于以上因素的考虑,为了能充分利用RPC的高强性能,并使其能在工程中得到广泛运用。本文对施加了无粘结预应力的RPC梁开展了静力及疲劳性能方面的试验研究及理论分析。并对比以往研究的普通钢筋RPC梁试验结果,突出无粘结预应力RPC梁的受拉性能。具体完成的内容如下:(1)综合的阐述了目前对于RPC的研究现状,总结归纳了已经得出的一些结论。并针对研究中相对较少涉及使用过程中又不可避免的问题提出本文研究内容。(2)通过材料力学性能试验,得到了RPC抗拉强度抗压强度及弹性模量,为理论分析提供基础数据。并详细描述了无粘结预应力RPC梁及普通钢筋RPC梁的静载及疲劳试验过程。对比了两种试验梁的静力性能,分析了普通钢筋RPC梁及无粘结预应力RPC梁在疲劳荷载作用下裂缝宽度挠度受压区边缘应变随加载次数的变化规律。(3)由于无粘结预应力RPC梁受力性能较为复杂,所以重点对无粘结预应力RPC受力特点进行分析。根据RPC材料抗拉强度高的特点,推导出了无粘结预应力RPC梁考虑受拉区抗拉作用的开裂弯矩正截面承载能力及跨中截面挠度的计算公式,并利用无粘结预应力筋应力增量与挠度的关系来建立预应力增量的计算公式。利用推导的公式计算出的值与试验实测值进行对比,结果较为接近。(4)结合无粘结预应力RPC梁的疲劳试验结果,通过非线性拟合得到了损伤变量的表达式。同时得到了随疲劳荷载循环次数的增加总应变及残余应变发展模型,利用残余应变模型推导出了RPC弹性模量退化模型。从损伤变量的定义出发推导了通过弹性模量的退化所表示的钢筋疲劳损伤模型。(5)以普通混凝土疲劳分析过程中所采用的基本假定为基础,结合无粘结预应力RPC梁具体的受力特点提出了疲劳分析所使用的基本假定。将疲劳非线性分析过程利用分段线性进行代替,推导出了无粘结预应力RPC梁疲劳全过程分析的简化方法,并与试验结果对比较为接近。
[Abstract]:Reactive Powder concrete (RPCs) has been favored by researchers for its excellent properties. What is the proportion of domestic and foreign scholars to their materials? Static performance of components? Corrosion resistance has been studied, but the fatigue properties of the components are seldom studied. In real life, members may bear fatigue load in most cases. At the same time, the stress distribution and failure form of reactive powder concrete members are different from those of ordinary concrete. Considering the above factors, in order to make full use of the high strength performance of RPC and make it widely used in engineering. In this paper, the static and fatigue behavior of RPC beams with unbonded prestressing is studied and analyzed theoretically. Compared with the test results of ordinary reinforced RPC beams, the tensile properties of unbonded prestressed RPC beams are highlighted. The detailed contents are as follows: 1) the current research status of RPC is expounded synthetically, and some conclusions are summarized and summarized. And in view of the relatively few problems that are unavoidable in the process of use in the research, this paper puts forward the research content. 2) through the test of mechanical properties of materials, the tensile strength of RPC is obtained. Compressive strength and elastic modulus provide basic data for theoretical analysis. The static load and fatigue tests of unbonded prestressed RPC beams and ordinary reinforced RPC beams are described in detail. In this paper, the static behavior of two kinds of test beams is compared, and the crack width of ordinary reinforced RPC beams and unbonded prestressed RPC beams under fatigue load is analyzed. Deflection? The stress characteristics of unbonded prestressed RPC beams are mainly analyzed because of the complexity of the mechanical behavior of unbonded prestressed RPC beams. According to the characteristics of high tensile strength of RPC material, the cracking moment of unbonded prestressed RPC beam considering tensile effect in tensile zone is deduced. The formulas for calculating the bearing capacity of the normal section and the deflection of the mid-span section are presented. The formula for calculating the prestress increment is established by using the relationship between the stress increment and the deflection of the unbonded prestressed tendons. By comparing the calculated values with the measured values, the results are close to the fatigue test results of unbonded prestressed RPC beams, and the expression of damage variables is obtained by nonlinear fitting. At the same time, the development model of total strain and residual strain with the increase of fatigue load cycle number is obtained, and the elastic modulus degradation model of RPC is derived by using the residual strain model. Based on the definition of damage variable, the fatigue damage model of steel bar expressed by the degradation of elastic modulus is based on the basic assumptions used in the fatigue analysis of ordinary concrete. Combined with the concrete stress characteristics of unbonded prestressed RPC beams, the basic assumptions used in fatigue analysis are put forward. By replacing the nonlinear fatigue analysis process with piecewise linear method, a simplified method for fatigue analysis of unbonded prestressed RPC beams is derived, which is close to the experimental results.
【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU37

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