现浇楼板对RC框架结构“强柱弱梁”影响研究

发布时间：2018-04-16 04:40

本文选题：RC框架结构 + 强柱弱梁　；参考：《中国地震局工程力学研究所》2017年硕士论文

【摘要】：钢筋混凝土(RC)框架结构中,现浇楼板与相邻框架梁整体强,形成协同受力机制。现浇楼板极大影响了相邻梁的受力和变形性能,导致规范要求的“强柱弱梁”破坏机制难以实现。目前,对于这一课题的研究要么针对框架梁柱节点处现浇楼板对梁荷载分配产生的影响,要么通过有限元软件建立结构模型整体分析楼板对结构屈服机制的影响,两者对于楼板本身工作机理以及楼板和梁柱的共同作用对结构性能的影响研究不足,均难以定量给出实际工作中楼板对相邻梁的影响。本文结合上述两种方法的优势,利用ABAQUS软件强大的非线性分析功能,对钢筋混凝土框架结构进行精细化实体单元建模,更准确的分析了楼板工作机理及对框架梁受力和对结构整体性能的影响。本文在总结大量相关文献的基础上,采用ABAQUS有限元软件,建立带楼板、空框架以及附加楼板质量的空框架三种类型RC框架结构模型,并通过模态分析和侧向静力加载的方式进行分析,从多个角度研究了现浇楼板对RC框架结构“强柱弱梁”屈服机制的影响。主要工作和成果如下:(1)通过模态分析和侧向静力加载的方法,采用有限元软件ABAQUS进行计算分析,对比了不同模型的自振频率以及能力曲线,研究了楼板对结构整体侧向刚度的影响规律,并定义结构侧向刚度增大系数来评估楼板对结构刚度的增强作用,最终通过回归分析给出了结构侧向刚度增大系数与板厚、梁高的拟合经验公式。结果显示楼板对RC框架结构整体侧向刚度的影响随着板厚的增大而增大,随着梁高的增大而减小。(2)通过分析带楼板与空框架模型破坏情况,对比了两者混凝土受拉破坏、混凝土受压破坏以及梁端受拉钢筋屈服情况,结果显示楼板对RC框架结构屈服机制影响显著,不利于“强柱弱梁”屈服机制的实现。并分析了楼板对RC框架结构影响的主要因素—板内钢筋的应力情况,研究了距离梁不同远近的板筋应力分布情况,同时综合分析了不同节点类型、板筋类型以及顶点位移等因素的影响。(3)通过分析不同板厚和梁高带楼板模型的板筋应力分布情况,给出了板筋应力分布随板厚和梁高的变化规律。进一步采用有效翼缘宽度度量楼板对框架梁受弯承载力的强化作用,结果显示有效翼缘宽度随板厚的增大而增大,随梁高增大在不同类型节点处变化情况有差异,在此基础上给出了不同类型节点处有效翼缘宽度随梁高和板厚变化的拟合经验公式。
[Abstract]:In the RC frame structure, the cast-in-place floor and adjacent frame beams are strong, forming a synergistic force mechanism.Cast-in-place slab greatly affects the mechanical and deformation behavior of adjacent beams, which results in the failure mechanism of "strong column and weak beam" which is required by the code is difficult to be realized.At present, the research on this subject is either aimed at the effect of cast-in-place floor at the joint of Liang Zhu frame on the load distribution of beam, or establishes the structural model to analyze the influence of floor on the yield mechanism of the structure by finite element software.It is difficult to quantify the influence of floor slab on adjacent beams in practical work because of the lack of research on the working mechanism of floor and the influence of floor and Liang Zhu on structural performance.Based on the advantages of the above two methods and the powerful nonlinear analysis function of ABAQUS software, this paper models the reinforced concrete frame structure with fine solid element.The working mechanism of floor slab and its influence on the stress of frame beam and the overall performance of the structure are analyzed more accurately.On the basis of summarizing a large number of related documents, this paper establishes three types of RC frame structure models with floor slab, hollow frame and additional floor mass by using ABAQUS finite element software.Through modal analysis and lateral static loading, the influence of cast-in-place floor on the yield mechanism of RC frame structure "strong column and weak beam" is studied from several angles.The main work and results are as follows: (1) by means of modal analysis and lateral static loading, finite element software ABAQUS is used to calculate and analyze, and the natural vibration frequency and capability curves of different models are compared.The influence of floor slab on the lateral stiffness of the whole structure is studied, and the enhancement factor of lateral stiffness of the structure is defined to evaluate the enhancement effect of the floor slab on the structural stiffness. Finally, the increase coefficient of lateral stiffness and the thickness of the slab are given by regression analysis.The empirical formula of beam height fitting.The results show that the influence of floor on the overall lateral stiffness of RC frame structure increases with the increase of slab thickness and decreases with the increase of beam height.The compressive failure of concrete and the yield of tensile steel bar at the end of beam show that the floor slab has a significant influence on the yield mechanism of RC frame structure, which is not conducive to the realization of yield mechanism of "strong column and weak beam".The stress of steel bar in the slab is analyzed, the stress distribution of the steel bar in different distance from the beam is studied, and the different types of joints are analyzed synthetically at the same time, the influence of floor slab on RC frame structure is analyzed.By analyzing the stress distribution of slab reinforcement with different slab thickness and beam height, the variation of plate reinforcement stress with slab thickness and beam height is given.Furthermore, the effective flange width is used to measure the strengthening effect of the floor slab on the flexural bearing capacity of the frame beam. The results show that the effective flange width increases with the increase of plate thickness and varies with the height of the beam at different types of joints.On this basis, the fitting empirical formula of the effective flange width with the beam height and plate thickness at different types of joints is given.
【学位授予单位】：中国地震局工程力学研究所
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU375.4

【参考文献】