混凝土开裂面的力学行为分析

发布时间：2018-03-01 19:12

本文关键词： 混凝土粗糙接触界面 W-M函数法微凸体剪切力摩擦因子　出处：《华南理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：通常情况下,混凝土构件产生裂缝后会沿最不利位置开展,混凝土构件产生裂缝后并非完全不能继续承受荷载,开展裂缝的两侧接触面因其表面是粗糙和不规则的,能够产生一定大小的摩擦力。混凝土之间的滑动能形成剪切力的传递,它与抗剪钢筋共同作用抵抗荷载。至于混凝土构件开裂后,剪切力到底能传递多少?剪力传递的系数有没有固定的数理统计规律?现行研究还尚无确切数值。本文对此提出了混凝土开裂面的力学行为分析命题,旨在解决两配的混凝土开裂后粗糙接触界面的力学行为,从而为混凝土构件裂缝开展区域的剪切力计算提供一定的力学理论基础。本文以接触力学为理论基础,通过比较分析发现混凝土开裂后的粗糙轮廓表现出的自仿射相似性特征与分形接触模型相吻合,因此可以运用分形学理论研究混凝土粗糙接触界面。本文通过采用分形学理论里的修正中点位移法和W-M函数法分别生成了混凝土粗糙接触的界面,再根据G-W模型对其界面进行简化。然后借助非线性有限元软件ABAQUS,建立以混凝土材料为分析对象的接触模型,对其进行数值分析。本文接触模型采用了“球帽”形的微凸体接触对。文中首先分析了一对微凸体接触对的接触压力与接触面积关系,得到了非线性关系曲线。然后给出了接触压力-接触面积关系曲线图和接触压力-位移关系曲线图,和Hertz理论预算结果进行对比,发现本文预算结果与Hertz理论结果非常接近,从而验证了模型的正确性。为了验证表面粗糙形貌对接触面积的影响,在模型里采用不同摩擦系数试算,最后发现单个微凸体里的摩擦因子对接触面积影响并不大。为了进一步验证微凸体接触对的力学行为特性,本文扩大了接触模型。将一对微凸体接触对扩展到了七对接触对,14个球帽高度按修正的指数分布拟合高斯分布。通过ABAQUS分析计算后,得到了扩大后接触压力与接触面积关系,结果表明考虑了多个接触对后的接触压力与接触面积关系呈线性关系,多个接触对之间互相关,多个微凸体接触对所产生的摩擦因子是稳定的。切向力与竖向力的比值系数符合线性递减规律,与W-M模型理论相吻合。
[Abstract]:In general, concrete members will develop along the most unfavorable position after cracks, and concrete members will not be completely unable to bear the load after cracks. The contact surfaces on both sides of the cracks are rough and irregular because their surfaces are rough and irregular. Can produce a certain size of friction. The slip between the concrete can form shear force transmission, it and shear reinforcement act together to resist the load. As for concrete members after cracking, how much shear force can be transferred? Is there a fixed mathematical statistical rule for the coefficient of shear transfer? In this paper, a proposition of mechanical behavior analysis of concrete cracking surface is put forward, which aims at solving the mechanical behavior of rough contact interface after cracking of two concrete. This provides a certain theoretical basis for the calculation of shear force in the crack area of concrete members. This paper takes contact mechanics as the theoretical basis. Through the comparative analysis, it is found that the self-affine similarity of the cracked rough contour is consistent with the fractal contact model. Therefore, the fractal theory can be used to study the rough contact interface of concrete. In this paper, the interface of rough contact of concrete is generated by using the modified midpoint displacement method and W-M function method in fractal theory. Then the interface is simplified according to the G-W model, and then the contact model of concrete material is established with the help of the nonlinear finite element software Abaqus. In this paper, a "ball cap" contact pair of microconvex body is used in the contact model. The relation between contact pressure and contact area of a pair of microconvex contact pairs is first analyzed in this paper. The nonlinear relation curve is obtained, and the curves of contact pressure-contact area relation and contact pressure-displacement relationship are given, and compared with the results of Hertz theory, it is found that the results of this paper are very close to those of Hertz theory. In order to verify the effect of rough surface topography on contact area, different friction coefficients were used in the model. Finally, it is found that the friction factor in a single microconvex body has little effect on the contact area. In this paper, the contact model is expanded. The contact pair of a pair of microconvex bodies is extended to seven pairs of contact pairs, and 14 spherical cap heights fit the Gao Si distribution according to the modified exponential distribution. The relationship between the expanded contact pressure and the contact area is obtained by ABAQUS analysis and calculation. The results show that the relationship between the contact pressure and the contact area is linear, and the relationship between the contact pressure and the contact area is correlated with each other. The ratio coefficient of tangential force to vertical force is in accordance with the law of linear decline, which is consistent with the theory of W-M model.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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