PVA纤维混凝土基本性能及在抗震节点中的应用研究

发布时间：2018-04-18 00:16

本文选题：框架节点 + PVA纤维混凝土　；参考：《湖北工业大学》2017年硕士论文

【摘要】：节点是框架结构的重要部位,起着连接梁柱、传递分配内力和协调结构变形的重要作用,历次地震震害调查表明,钢筋混凝土框架类结构的破坏多集中在节点核心区及其附近区域,因节点失效引起的结构破坏一般难以修复。要使结构满足延性框架中的“强柱弱梁”抗震设计原则,则截面尺寸往往过大或箍筋配置较多,给施工带来较大麻烦,同时难以有效控制裂缝的产生。PVA(聚乙烯醇)纤维作为近年来应用于结构抗震关键部位的一种外掺纤维,越来越受到广泛关注。PVA纤维增强水泥基复合材料利用断裂力学和微观力学原理在纤维体积掺量约为2%的情况下获得3%以上的拉应变能力,具有优良的韧性、较好的非线性变形和显著的裂缝控制能力,可使传统水泥基材料的脆性破坏模式转变为韧性破坏模式。因此PVA纤维增强混凝土(PVA Fiber Reinforced Concrete,简称PFRC)的研究与应用必将为混凝土结构的控裂和性能改善提供新的解决方法。本文对PVA纤维混凝土的基本力学性能及其在抗震节点开展试验研究,主要研究内容如下:1.制作24个PVA纤维混凝土标准试块,进行基本力学性能试验。利用试验过程和结果描述纤维混凝土开裂过程,将其力学性能与普通混凝土进行对比分析。2.针对8个不同的PVA纤维混凝土局部增强框架节点试件和1个对比试件进行了低周往复加载试验,主要参数变化为节点核心区箍筋配箍率和试验轴压比,研究PVA纤维增强混凝土替代框架节点核心区抗剪箍筋的可行性。3.利用OpenSees有限元分析软件模拟PVA纤维混凝土局部增强框架节点的低周反复加载试验,研究此类节点的受力特点和破坏机理,计算了位移延性系数、刚度退化及粘滞阻尼系数。4.对PVA纤维混凝土局部增强框架抗震节点试件受剪模型进行简化,建立了节点核心区拉压杆模型,对比分析了试验值和数值模拟值,分析了其抗剪承载能力及其影响因素。5.在试验基础上利用有限元分析软件OpenSees模拟了不同柱梁弯矩系数条件下的PVA纤维混凝土局部增强框架节点的抗震性能,研究PVA纤维混凝土实现“强柱弱梁”要求的最佳柱梁弯矩比值。
[Abstract]:The joint is an important part of the frame structure, which plays an important role in connecting Liang Zhu, transferring and distributing internal forces and coordinating the deformation of the structure.The damage of reinforced concrete frame structures is mainly concentrated in the core area of joints and its vicinity, and the damage caused by failure of joints is usually difficult to repair.In order to make the structure meet the seismic design principle of "strong column and weak beam" in ductile frame, the cross section size is often too large or the stirrups are more, which brings more trouble to the construction.At the same time, it is difficult to control the crack effectively. PVA (polyvinyl alcohol) fiber is a kind of admixture fiber which has been used in the key parts of structural earthquake resistance in recent years.More and more attention has been paid to the tensile strain ability of PVA fiber reinforced cement matrix composites by using fracture mechanics and micromechanical principles under the condition of about 2% fiber volume, which has excellent toughness.The brittle failure mode of traditional cement-based materials can be transformed into a ductile failure mode because of its good nonlinear deformation and remarkable crack control ability.Therefore, the research and application of PVA fiber reinforced concrete Fiber Reinforced crete will provide a new solution for the crack control and performance improvement of concrete structures.In this paper, the basic mechanical properties of PVA fiber reinforced concrete and its application in seismic joints are studied. The main contents are as follows: 1.24 PVA fiber reinforced concrete standard test blocks were made and the basic mechanical properties were tested.The cracking process of fiber reinforced concrete (FRC) is described by means of experimental process and results. The mechanical properties of FRC are compared with that of ordinary concrete.The low cycle reciprocating loading tests were carried out for 8 different specimens of PVA fiber reinforced concrete locally reinforced frame joints and 1 contrast specimen. The main parameters were the ratio of stirrups in the core region of the joints and the axial compression ratio of the tests.This paper studies the feasibility of PVA fiber reinforced concrete instead of shear stirrups in the core zone of frame joints.OpenSees finite element analysis software is used to simulate the low cycle repeated loading test of PVA fiber reinforced concrete locally reinforced frame joints. The mechanical characteristics and failure mechanism of the joints are studied. The displacement ductility coefficient, stiffness degradation and viscous damping coefficient .4 are calculated.In this paper, the shear model of PVA fiber reinforced local reinforced seismic joint is simplified, and the tension and compression bar model in the core zone of the joint is established. The test value and numerical simulation value are compared and analyzed, and the shear bearing capacity and its influencing factors are analyzed.On the basis of the experiment, the seismic behavior of PVA fiber reinforced concrete partially reinforced frame joints under different moment coefficients of column beams is simulated by using finite element analysis software OpenSees.The optimum moment ratio of PVA fiber reinforced concrete for "strong column and weak beam" is studied.
【学位授予单位】：湖北工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU37;TU352.11

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