CFRP板条嵌入式加固RC框架节点抗震性能研究

发布时间：2018-06-21 20:00

本文选题：钢筋混凝土节点 + CFRP板条　；参考：《上海应用技术大学》2017年硕士论文

【摘要】：钢筋混凝土(RC)框架结构是工业与民用建筑工程中最常用的结构形式之一,提高其抗震能力,对有效减轻震害具有重要的现实意义。按早期规范设计的RC框架节点往往不能满足现行抗震规范的要求,如存在节点核心区箍筋配置不足等问题,有悖于“强节点弱构件”的抗震概念设计原则,在地震中往往发生剪切破坏甚而导致建筑的倒塌。对于RC节点的抗震加固,已有大量的试验研究和工程实践,常用的加固方法主要有混凝土加大截面、粘贴钢板、外包型钢、高强钢绞线网-聚合物砂浆和粘贴纤维增强复合材料(Fiber Reinforced Polymer/Plastic, FRP)等。与其它方法相比较,FRP具有高效高强、耐久性好、易施工等优点,然而外贴FRP加固RC框架节点存在着FRP易剥离、梁铰靠近柱面等缺陷。基于此,本文提出了基于塑性铰外移的碳纤维(CFRP)板条嵌入式(Near-surface-mounted,简称NSM)加固RC节点的加固方法,并通过拟静力试验进行了验证,并在分析CFRP板条应变分布和发展规律的基础上,提出一种NSM CFRP板条加固RC节点的抗剪强度计算方法,为其工程设计和应用提供理论依据。本文主要工作及研究成果如下:1.设计并制作了 4个十字形RC框架节点,其中1个按现行规范要求设计的抗震节点,3个为核心区未配箍筋的空节点。结合转移塑性铰的抗震理念及NSM加固方法,以CFRP板条面积、加固间距为主要参数,对其中2个空节点进行加固。对试件节点进行低周反复荷载下的抗震试验研究,深入对比分析了破坏模式、耗能、延性及强度、刚度退化等主要性能指标,以及CFRP板条应变分布及发展情况。2.试验结果表明,采用CFRP板条嵌入式加固能够提高节点承载力,改善构件的延性,阻滞构件刚度退化,合理的布置CFRP板条间距甚至能够使其破坏模式由节点核心区剪切破坏转为远离柱面的梁铰破坏。3.鉴于NSM CFRP板条加固RC节点抗剪强度的理论研究不足,根据水平地震作用下节点核心区处于双向拉压应力状态这一受力特征,基于混凝土双向拉压强度准则,提出了一个CFRP板条NSM加固RC节点的抗剪强度计算方法,简便实用且精度高。
[Abstract]:Reinforced concrete (RC) frame structure is one of the most commonly used structures in industrial and civil engineering. It is of great practical significance to improve its seismic resistance and reduce earthquake damage effectively. The RC frame joints designed according to the early codes often fail to meet the requirements of the current seismic code. For example, there are insufficient stirrups in the core areas of the joints, which is contrary to the seismic conceptual design principle of "strong joints and weak members". Shear damage and even collapse of buildings often occur in earthquakes. For the seismic strengthening of RC joints, there have been a lot of experimental research and engineering practice. High strength steel wire mesh-polymer mortar and bonded fiber reinforced composite material fiber reinforced polymer / plastic (FRP) etc. Compared with other methods, FRP has the advantages of high efficiency, good durability, easy construction and so on. However, FRP is easy to peel off the joints of RC frame strengthened with FRP, and the beam hinge is close to the cylindrical surface. Based on this, this paper presents a reinforcement method of RC joints strengthened with CFRP-based CFRP-based plastic hinges embedded with Near-surface-mountable (NSM), which is verified by quasi-static tests, and based on the analysis of the strain distribution and development law of CFRP plates. A new method for calculating the shear strength of RC joints strengthened with NSM CFRP plates is presented, which provides a theoretical basis for the engineering design and application. The main work and research results of this paper are as follows: 1. Four cross-shaped RC frame joints are designed and manufactured, one of which is designed according to the requirements of the current code, and three are empty joints with no stirrups in the core area. Combined with the aseismic concept of the transfer plastic hinge and the method of NSM reinforcement, two empty joints were strengthened with CFRP slab area and reinforcement spacing as the main parameters. The seismic test of the joints under low cyclic loading is carried out, and the main performance indexes, such as failure mode, energy dissipation, ductility and strength, stiffness degradation, and the strain distribution and development of CFRP slab are compared and analyzed. The experimental results show that CFRP slab embedded reinforcement can improve the bearing capacity of the joints, improve the ductility of the members, and block the degradation of the stiffness of the members. The reasonable arrangement of CFRP slab spacing can even change the failure mode from the shear failure in the core zone of the joint to the beam hinge failure away from the cylinder. 3. In view of the lack of theoretical study on the shear strength of RC joints strengthened with NSM CFRP sheets, according to the stress characteristics that the core region of the joints is in the state of biaxial tension and compression stress under horizontal earthquake, based on the criterion of concrete biaxial tension-compression strength. A method for calculating the shear strength of RC joints strengthened with CFRP strip NSM is presented, which is simple, practical and accurate.
【学位授予单位】：上海应用技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU375.4;TU352.11

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