【作者】 赵海龙；

【导师】 王铁成；

【作者基本信息】 天津大学 ， 结构工程， 2011， 博士

【摘要】 混凝土异形柱框架结构由于良好的使用功能而逐渐在工程领域得到广泛的应用。但由于异形柱底层柱根部和节点等薄弱部位的存在,限制了异形柱结构的结构高度和在抗震区的进一步推广。因此,本文提出局部采用纤维进行增强的方法,对异形柱结构的薄弱部位进行纤维增强,研究纤维在改善异形柱结构薄弱部位抗震性能上的增强作用,为异形柱结构进一步推广和应用提供试验和研究依据。具体的研究工作包括:通过柱根部采用聚丙烯纤维和钢纤维增强的异形柱在反复荷载作用下试验,对比分析破坏状态、承载能力和延性、抗震性能等性能指标,研究纤维种类对异形柱的增强效果。对比分析表明:纤维增强可以改善异形柱的破坏特征,能够提高异形柱的承载能力和变形能力,对T形和L形柱的抗震性能具有显著的改善。综合比较发现,钢纤维对异形柱的各阶段受力特征增强效果优于聚丙烯纤维。通过节点采用聚丙烯纤维和钢纤维增强的6个异形柱中节点和4个边节点的抗震性能试验,对比分析节点的破坏形态,承载能力和变形能力,抗震性能以及各阶段受力性能,研究纤维品种及掺入范围对节点的增强效果。研究表明:纤维可以推迟节点核心区开裂,减小裂缝宽度,改善节点破坏特征。纤维增强可以改善异形柱节点承载能力、延性和抗震性能。节点区及相邻梁端一倍梁高范围采用钢纤维增强节点的纤维增强效果最佳。在分析异形柱节点受力机理和传力机制的基础上,统计52个异形柱节点剪切试验结果,分析节点受剪承载力变化规律并提出纤维增强异形柱节点的受剪承载力计算公式,建立纤维增强异形柱节点的设计计算方法。计算分析表明:本文提出的节点受剪承载力公式偏安全且有一定安全储备。对三种混凝土进行力学性能和本构关系研究和分析。研究表明:纤维增强对混凝土抗压强度和峰值应变均没有显著影响,但可以大幅度提高极限应变,提高混凝土的压缩韧性和韧度,改善混凝土脆性破坏特征。在分析的基础上建立纤维混凝土的本构模型,对中节点建立有限元模型进行分析,补充研究纤维掺入范围对异形柱节点承载力的影响,分析得出纤维掺入范围在节点区及两端0.5~1倍梁高范围节点承载力最大的结论。基于上述试验和理论分析,提出了纤维增强异形柱节点工程设计建议。更多还原

【Abstract】 The RC frame structure with specially shaped columns is widely used in field of engineering for the favorable service function. But the existence of weak parts of joints and legs of specially shaped columns in bottom floor restrict the structure height and the further generalization of structure with specially shaped columns. Therefore the method of fiber reinforcement in local area is proposed to make reinforcement to weak parts of structure with specially shaped columns. Fiber reinforcement to the weak parts of structure with specially shaped columns in seismic behaviors is investigated to make this structure generalize further and provide the experiment and research foundation. The detailed work of this paper is stated as follows:According to cyclic loading test of specially shaped columns with leg reinforced by polypropylene fiber and steel fiber, the aspects of failure characteristic, shearing capacity, ductility and seismic behaviors are compared between specimens with and without fiber reinforcement to make the analysis. It is shown in the results that the failure characteristics can be improved and the bearing and deforming capacity can be increased with fiber reinforcement. The conclusion can be drawn from total comparison that the reinforcing effect of steel fiber is better than that of polypropylene fiber.Based on the tests on seismic behaviors of six interior joints and four exterior joints with specially shaped joints reinforced with polypropylene fiber and steel fiber, comparison is made on failure characteristic, shearing and deforming capacity, seismic behaviors and mechanical behaviors in loading to study on the fiber reinforcement on different fiber varieties and fiber using areas. It is shown in the study that fiber could delay the cracking of core area of joint, decrease the width of cracks, alleviate the failure pattern of joint and also improve the bearing capacity, ductility, and seismic behaviors. The best fiber reinforcing effect occurred in that fiber reinforcement on the core area of joints and the area of beam height.On the basis of mechanical mechanism and force transferring process, 52 test results for joints with specially shaped columns are statistically collected to study the changing rule of shearing capacity, based on which the formula of shearing capacity of joints with specially columns is proposed to provide a design calculation method for fiber reinforced joints with specially shaped columns. Calculation and analysis shows that the formula ares rational and save in calculation with security degree.It is shown from the test results and analysis on the constitutive relationship, the compressive strength and peak strain of concrete is influenced little by fiber reinforcement, while the ultimate strain can be increased in large degree, the compressive toughness and tenacity can be improved to make the brittleness of failure characteristics of concrete. The constitutive model of fiber reinforced concrete is established according to the analyzing and test results, which is used in the finite element analysis on the interior joints with specially shaped columns to analyze the influence of fiber using area to the joint bearing capacity in supplement. It is shown from the analysis that the bearing capacity of joints have a maximum with the fiber using area of the core area of joint including half to one times of the beam height.The engineering design suggestions on fiber reinforced joints with specially shaped columns are put forward on the basis of the above test and analysis.更多还原