基于人工神经网络的双箍筋约束混凝土柱极限承载力影响参数分析
发布时间：2018-11-17 20:30
【摘要】：建筑行业在近十年的发展中相比之前发生了翻天覆地的变化,这种变化可以体现在两个方面,其一是结构复杂,其二是建筑层数逐年增加。基于以上原因,对承重结构性能的改善便成为了广大设计人员关注的重点。就柱体而言,传统的单箍筋约束混凝土柱已满足不了结构对承载力的要求,越来越多的学者开始将重心放在了对双箍筋约束混凝土柱的研究上。其抗压能力强,极限承载力大的特点备受好评。然而,因为其施工复杂,制作成本高等因素的限制,在现场施工中很难看到它的身影。那么如何找到构造中影响较小的因素,合理配置构造形式达到节约成本的目的便成为了本文的研究课题。在整理近几年的相关文献时,不难发现侧重点多集中于受力特点,结构优势等因素。文章另辟蹊径,在实验的基础上利用神经网络对影响双箍筋约束混凝土柱竖向极限承载力的七项参数进行分析,并研究其影响特征。文章设计了9个内圆外方双箍筋约束混凝土柱,共分为三组,每组采用不同等级的混凝土。在箍筋配置上,以内外层箍筋直径,内外层箍筋间距,内外层箍筋配箍特征值,以及内层箍筋圆直径等七组变量作为研究对象。随后分别对其施加竖向荷载,并初步探究各个参数对承载力的影响。实验结果表明:当钢筋强度,混凝土强度被控制在相同的条件下时,适当提高外层约束箍筋的配箍特征值,可以提高混凝土柱的延性;在一定程度内提高混凝土的强度可以提高构件的极限承载力。应用ABAQUS有限元软件对实验进行验证和进一步的研究。通过应力分布图发现了混凝土柱的受力机理:起初整个混凝土柱体类似于弹性构件,此时的混凝土和纵筋共同承受压力。随后,混凝土和纵筋横向变形膨胀,并将荷载传递给箍筋;在达到竖向极限承载力之前的一段时间内,荷载主要由箍筋承担。在到达极限承载力后,钢筋大部分处于屈服状态,形变增长显著;在模拟对比中发现只有第六组误差较大,其他组均吻合良好。这一结果证明了实验的可靠性。通过人工神经网络对内圆外方双箍筋约束混凝土柱进行模拟分析。结果表明:内外层箍筋间距在一定范围增大时,构件的极限承载力会随之降低,外层箍筋间距变化时产生的影响更为显著;当内外层箍筋直径逐渐增大时,约束混凝土构件的竖向极限承载力并没有表现出明显的规律性变化;当内层箍筋圆直径逐渐增大时,柱体竖向极限承载力随之减小;内外配箍特征值在一定范围增大时,柱体的竖向承载力随着配股特征值的增大而增大。这对更好的揭示影响其承载力的内部参数因素和对控制工程的成本有着重要的理论和实际意义。
[Abstract]:Compared with the past ten years, the construction industry has undergone earth-shaking changes, which can be reflected in two aspects: one is the complexity of the structure, the other is the increase of the building floor number year by year. Based on the above reasons, the improvement of load-bearing structure performance has become the focus of attention of the majority of designers. As far as columns are concerned, the traditional concrete columns with single stirrups can not meet the requirements of the bearing capacity of the structure. More and more scholars begin to focus on the study of concrete columns with double stirrups. Its strong compressive capacity, the characteristics of large ultimate bearing capacity is highly praised. However, because of its complex construction, high production cost and other factors, it is difficult to see it in the field construction. So how to find the less influential factors in the structure, and how to reasonably allocate the structure form to achieve the purpose of cost saving has become the research topic of this paper. It is not difficult to find that the stress characteristics, structural advantages and other factors are the focal points in sorting out the relevant documents in recent years. On the basis of experiments, the paper analyzes the seven parameters which affect the vertical ultimate bearing capacity of concrete columns confined by double stirrups, and studies its influence characteristics. In this paper, 9 concrete columns with double stirrups are designed and divided into three groups. Each group uses concrete of different grades. In the configuration of stirrups, there are seven variables, such as the diameter of inner and outer stirrups, the spacing between inner and outer stirrups, the eigenvalues of stirrups, and the diameter of inner stirrups. Then the vertical load is applied to it, and the influence of each parameter on the bearing capacity is studied. The experimental results show that the ductility of concrete columns can be improved by properly increasing the hoop characteristic value of outer confined stirrups when the strength of steel bar and concrete strength are controlled under the same conditions. To a certain extent, the ultimate bearing capacity of members can be improved by increasing the strength of concrete. ABAQUS finite element software is used to verify the experiment and further research. The stress distribution diagram shows the stress mechanism of concrete columns: at first, the whole concrete column is similar to elastic members, and the concrete and longitudinal tendons are subjected to pressure together. Then the concrete and longitudinal tendons are deformed and expanded laterally and the load is transferred to the stirrups and the load is mainly borne by the stirrups during a period of time before the ultimate vertical bearing capacity is reached. After the ultimate bearing capacity is reached, most of the steel bars are in the yield state, and the deformation increases significantly. In the simulation comparison, only the sixth group has a larger error and the other groups are in good agreement with each other. This result proves the reliability of the experiment. The artificial neural network is used to simulate and analyze the confined concrete columns with double stirrups inside and outside the inner circle. The results show that when the internal and external stirrups spacing increases in a certain range, the ultimate bearing capacity of the members will decrease, and the influence of the outer stirrups spacing will be more significant. When the diameter of inner and outer stirrups increases gradually, the vertical ultimate bearing capacity of confined concrete members does not show obvious regularity, and when the diameter of inner stirrups increases gradually, the vertical ultimate bearing capacity of columns decreases. The vertical bearing capacity of the column increases with the increase of the eigenvalue of the internal and external hoop when the eigenvalue of the internal and external hoop increases in a certain range. It is of great theoretical and practical significance to better reveal the internal parameter factors that affect the bearing capacity and to control the cost of the project.
【学位授予单位】：吉林建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU375.3
[Abstract]:Compared with the past ten years, the construction industry has undergone earth-shaking changes, which can be reflected in two aspects: one is the complexity of the structure, the other is the increase of the building floor number year by year. Based on the above reasons, the improvement of load-bearing structure performance has become the focus of attention of the majority of designers. As far as columns are concerned, the traditional concrete columns with single stirrups can not meet the requirements of the bearing capacity of the structure. More and more scholars begin to focus on the study of concrete columns with double stirrups. Its strong compressive capacity, the characteristics of large ultimate bearing capacity is highly praised. However, because of its complex construction, high production cost and other factors, it is difficult to see it in the field construction. So how to find the less influential factors in the structure, and how to reasonably allocate the structure form to achieve the purpose of cost saving has become the research topic of this paper. It is not difficult to find that the stress characteristics, structural advantages and other factors are the focal points in sorting out the relevant documents in recent years. On the basis of experiments, the paper analyzes the seven parameters which affect the vertical ultimate bearing capacity of concrete columns confined by double stirrups, and studies its influence characteristics. In this paper, 9 concrete columns with double stirrups are designed and divided into three groups. Each group uses concrete of different grades. In the configuration of stirrups, there are seven variables, such as the diameter of inner and outer stirrups, the spacing between inner and outer stirrups, the eigenvalues of stirrups, and the diameter of inner stirrups. Then the vertical load is applied to it, and the influence of each parameter on the bearing capacity is studied. The experimental results show that the ductility of concrete columns can be improved by properly increasing the hoop characteristic value of outer confined stirrups when the strength of steel bar and concrete strength are controlled under the same conditions. To a certain extent, the ultimate bearing capacity of members can be improved by increasing the strength of concrete. ABAQUS finite element software is used to verify the experiment and further research. The stress distribution diagram shows the stress mechanism of concrete columns: at first, the whole concrete column is similar to elastic members, and the concrete and longitudinal tendons are subjected to pressure together. Then the concrete and longitudinal tendons are deformed and expanded laterally and the load is transferred to the stirrups and the load is mainly borne by the stirrups during a period of time before the ultimate vertical bearing capacity is reached. After the ultimate bearing capacity is reached, most of the steel bars are in the yield state, and the deformation increases significantly. In the simulation comparison, only the sixth group has a larger error and the other groups are in good agreement with each other. This result proves the reliability of the experiment. The artificial neural network is used to simulate and analyze the confined concrete columns with double stirrups inside and outside the inner circle. The results show that when the internal and external stirrups spacing increases in a certain range, the ultimate bearing capacity of the members will decrease, and the influence of the outer stirrups spacing will be more significant. When the diameter of inner and outer stirrups increases gradually, the vertical ultimate bearing capacity of confined concrete members does not show obvious regularity, and when the diameter of inner stirrups increases gradually, the vertical ultimate bearing capacity of columns decreases. The vertical bearing capacity of the column increases with the increase of the eigenvalue of the internal and external hoop when the eigenvalue of the internal and external hoop increases in a certain range. It is of great theoretical and practical significance to better reveal the internal parameter factors that affect the bearing capacity and to control the cost of the project.
【学位授予单位】：吉林建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU375.3
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