考虑动力效应的钢筋混凝土柱抗震性能研究

发布时间：2018-11-28 08:14

【摘要】：钢筋混凝土结构在地震作用下的动力响应通常会受到荷载速率的影响,而钢筋混凝土柱作为主要的承重构件,其在不同加载速率下的抗震性能研究尚且较少,同时,目前的结构抗震设计规范并未涉及由荷载速率引起的钢筋混凝土构件力学性能和变形性能变化方面的条款。本文基于试验研究和数值计算相结合的方法,分析了地震荷载速率作用下钢筋混凝土柱的率敏感性对其力学特性的影响,主要内容归结如下： (1)试验研究了加载速率对钢筋混凝土柱力学性能和变形性能的影响。主要考虑的因素有：剪跨比、轴压比、混凝土强度、纵筋强度等级、纵向配筋率、体积配箍率、加载模式(单向加载、双向加载和变轴力加载)和加载速率。试验结果表明,随着加载速率的提高,构件的屈服承载力和极限承载力均有所增加,且屈服承载力增加的程度更为显著；加载速率的提高导致构件的强度退化、刚度退化和损伤加剧,延性略有降低,耗能则有所增加；轴力变化加剧了构件的率敏感性,使构件在加载后期提前失稳；双向加载过程中存在的耦联作用则进一步加剧了柱强度退化和刚度退化的进程。另外,基于理论分析发现,在快速加载条件下柱的截面受压区高度略有减小,加载速率导致柱的抗弯承载力的增长水平远高于抗剪承载力,同时,加载速率的提高致使构件的破坏机理也发生明显改变。 (2)试验研究了钢筋混凝土柱在不同加载路径下的动力特性,主要考虑的加载路径有：单向循环加载、十字形加载、菱形加载和圆形加载路径。试验结果表明,加载路径和加载速率的综合作用使柱的强度退化、刚度退化、延性降低程度均明显提高；通过双向加载条件下的等效阻尼比计算结果,可以看到,圆形加载路径下柱的耗能能力最强;加载速率使柱的荷载-位移骨架曲线在加载后期斜率下降更为迅速,这种现象在菱形加载路径下表现更为显著；经过回归分析给出了不同加载路径下静力和动力加载的等效阻尼比计算的经验公式。 (3)基于OpenSees中的分布塑性铰模型,数值计算给出了不同材料应变率下柱单调加载条件下的荷载-位移关系曲线和地震作用下柱的动力响应,并通过回归分析给出了不同材料应变率下柱极限承载力的动力增长因子经验公式。另外,基于OpenSees中的BeamwithHingesElement单元,引入钢筋和混凝土材料的应变率效应,考虑了构件的双向弯曲、轴力的耦联作用及剪切、粘结滑移效应,编制了钢筋混凝土柱的Tcl程序,对不同加载路径下的钢筋混凝土柱进行了数值模拟,并与试验结果进行了对比。
[Abstract]:The dynamic response of reinforced concrete structures under earthquake is usually affected by the load rate. However, as the main load-bearing members, the seismic behavior of reinforced concrete columns under different loading rates is still less studied, and at the same time, The current code for seismic design of structures does not deal with the changes in mechanical properties and deformation properties of reinforced concrete members caused by load rate. Based on the combination of experimental study and numerical calculation, this paper analyzes the effect of the rate sensitivity of reinforced concrete columns on their mechanical properties under the action of seismic load rate. The main contents are summarized as follows: (1) the effect of loading rate on the mechanical and deformation properties of reinforced concrete columns is studied. The main factors considered are: shear span ratio, axial compression ratio, concrete strength, longitudinal reinforcement strength grade, longitudinal reinforcement ratio, volume hoop ratio, loading mode (unidirectional loading, biaxial loading and variable axial force loading) and loading rate. The experimental results show that with the increase of loading rate, both the yield bearing capacity and the ultimate bearing capacity of the members increase, and the degree of the increase of the yield bearing capacity is more obvious. The increase of loading rate leads to the degradation of strength, the degradation of stiffness and damage, the decrease of ductility and the increase of energy consumption, the change of axial force increases the sensitivity of the component, which makes the member lose stability in advance in the later stage of loading. The coupling action in the bidirectional loading process further intensifies the degradation of strength and stiffness of columns. In addition, based on the theoretical analysis, it is found that the height of the section compression zone decreases slightly under the rapid loading condition, and the loading rate leads to the increase of the flexural capacity of the column far higher than that of the shear bearing capacity, and at the same time, With the increase of loading rate, the failure mechanism of the components is obviously changed. (2) the dynamic characteristics of reinforced concrete columns under different loading paths are studied experimentally. The main loading paths are unidirectional cyclic loading, cross loading, rhombic loading and circular loading path. The experimental results show that the strength, stiffness and ductility of the columns are degraded by the combined action of loading path and loading rate. Through the results of the equivalent damping ratio under biaxial loading, it can be seen that the energy dissipation capacity of the column under circular loading path is the strongest. The loading rate makes the load-displacement skeleton curve of the column decrease more rapidly at the later stage of loading, which is more obvious under the rhombus loading path. The empirical formulas for calculating the equivalent damping ratio of static and dynamic loads under different loading paths are given by regression analysis. (3) based on the distributed plastic hinge model in OpenSees, the load-displacement curve under monotone loading and the dynamic response of the column under earthquake are obtained. The empirical formula of dynamic growth factor of column ultimate bearing capacity under different material strain rates is given by regression analysis. In addition, based on the BeamwithHingesElement element in OpenSees, the strain rate effect of steel bar and concrete material is introduced, and the Tcl program of reinforced concrete column is programmed by considering the bidirectional bending, coupling effect of axial force and shear, bond-slip effect. The reinforced concrete columns with different loading paths are numerically simulated and compared with the experimental results.
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU375.3;TU352.11

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