施工缺陷对RC框架梁柱节点力学性能的影响

发布时间：2018-02-28 08:17

本文关键词： 施工缺陷 RC框架结构梁柱节点力学性能　出处：《西安工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：节点核心区受力复杂,是钢筋混凝土(RC)框架结构传力的关键部件。由于RC框架结构的梁、柱纵向钢筋及箍筋在节点处相交,所以节点核心区的钢筋分布非常密集,这将导致梁柱节点在施工中容易出现浇筑困难和振捣不密实的情况·,此外,节点施工受支模、钢筋绑扎等工序影响,易产生节点箍筋移位、箍筋缺失及纵筋露出等施工缺陷,这些施工缺陷将给RC梁柱节点以及整体结构的受力性能带来影响。现有节点试验及数值模拟研究大多围绕节点抗震性能研究、地震损伤模式和节点加固方法开展,关于节点施工缺陷影响的研究尚不充分,因此,研究施工缺陷对钢筋混凝土框架节点性能的影响具有十分重要的意义。总结了实际工程中梁柱节点施工缺陷的成因和特点,归纳和总结了现有节点传力机理及其计算方法。利用ABAQUS软件建立了带有节点漏浆、箍筋缺失等施工缺陷的RC框架梁柱节点有限元分析模型,在节点模型的梁端及柱端分别施加逐级增大的单向荷载,研究施工缺陷对梁柱节点力学性能的影响。研究结果表明,带施工缺陷节点模型在荷载作用下,钢筋应力分布较完好节点模型发生了明显的改变,完好节点模型的应力主要集中于梁端部,带缺陷节点模型的应力向节点核心区内部集中,钢筋在节点处发生屈服;通过对比带缺陷节点与完好节点在单向加载下的力与位移关系曲线知,带缺陷节点的承载能力低于完好节点;带施工缺陷节点在荷载作用下的横向变形大于完好节点,节点核心区的约束能力出现了下降,延性性能大大降低。基于ABAQUS有限元分析结果,利用SeismoStruct软件建立了考虑节点施工缺陷的一榀框架非线性分析模型,通过对其进行地震作用下的非线性动力时程分析,研究了节点施工缺陷对RC框架结构抗震性能的影响。分析结果表明,与完好框架结构相比,带节点施工缺陷框架结构的自振周期得到延长,带节点缺陷结构的各楼层位移响应均大于完好结构,说明考虑施工缺陷后,结构的刚度出现了降低;在多遇及罕遇地震作用下,完好结构的各层层间剪力均大于带节点缺陷结构,同时其各层层间位移小于带节点缺陷结构,说明带节点损伤模型的抗震能力明显降低。文中给出的考虑梁柱节点施工缺陷的RC框架结构简化杆系有限元分析模型的数值建模方法,可以通过折减缺陷节点连接单元的刚度来模拟节点缺陷对结构整体力学性能的影响,为实际工程中节点施工缺陷的评价以及加固方案的选取提供指导,具有一定的工程应用价值,同时也为进一步开展考虑梁柱节点施工缺陷的RC框架结构相关性能研究奠定了基础。
[Abstract]:The stress in the core area of the joint is complex, and it is the key component of the transmission force in the RC frame structure. Because the beam, column longitudinal reinforcement and stirrups of RC frame structure intersect at the joint, the distribution of the reinforcement in the core area of the joint is very dense. This will lead to the construction of Liang Zhu joint easy to be difficult to place and vibration is not dense. In addition, the node construction is affected by supporting formwork, steel bar binding and other working procedures, easy to produce joint stirrups displacement, lack of stirrups, longitudinal bars exposed and other construction defects, These construction defects will affect the mechanical behavior of RC Liang Zhu joints and the whole structure. Most of the existing joint tests and numerical simulation studies focus on the seismic behavior of joints, seismic damage mode and joint reinforcement methods. The research on the influence of joint construction defects is not enough, so it is of great significance to study the effect of construction defects on the performance of reinforced concrete frame joints. The causes and characteristics of Liang Zhu joint construction defects in practical projects are summarized. In this paper, the mechanism and calculation method of the existing joint force transfer are summarized and summarized. The finite element analysis model of Liang Zhu joint of RC frame with defects such as joint leakage and lack of stirrups is established by using ABAQUS software, and the finite element analysis model of Liang Zhu joint of RC frame is established. The effects of construction defects on the mechanical properties of Liang Zhu joints are studied by applying a step by step increasing unidirectional load at the beam and column ends of the joint model. The results show that the joint model with construction defects is subjected to load. The stress distribution of the reinforced bar is obviously changed in the intact joint model. The stress of the intact joint model is mainly concentrated at the end of the beam, the stress of the model with defects is concentrated inside the core zone of the node, and the steel bar yields at the joint. By comparing the stress and displacement curves of the joints with and without defects under unidirectional loading, the load-carrying capacity of the joints with defects is lower than that of the intact joints, and the transverse deformation of the joints with construction defects is larger than that of the intact joints under load. Based on the results of ABAQUS finite element analysis, a nonlinear analysis model of frame considering joint construction defects is established by using SeismoStruct software. Through the nonlinear dynamic time history analysis of the RC frame structure under seismic action, the influence of the joint construction defects on the seismic behavior of RC frame structure is studied. The results show that the structure is better than the intact frame structure. The natural vibration period of the frame structure with joint defects is prolonged, and the displacement response of each floor of the frame structure with joint defects is larger than that of the intact structure, which indicates that the stiffness of the structure decreases after considering the construction defects, and under the action of frequent and rare earthquakes, The shear force between layers of intact structures is greater than that of defective structures with joints, and the displacement between layers is smaller than that of defective structures with joints. It is shown that the seismic capacity of the damage model with joints is obviously reduced. The numerical modeling method for simplified finite element analysis model of RC frame structure considering the construction defects of Liang Zhu joints is presented. The effects of joint defects on the overall mechanical properties of the structure can be simulated by reducing the stiffness of the connection elements of defective joints, which can provide guidance for the evaluation of joint construction defects and the selection of reinforcement schemes in practical engineering. It has certain engineering application value and lays a foundation for further research on the related performance of RC frame structure considering the construction defects of Liang Zhu joint.
【学位授予单位】：西安工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU375

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