GFRP-混凝土组合梁弯曲性能及损伤预警研究

发布时间：2018-12-12 02:56

【摘要】：轻质、高强、耐久是现代桥梁工程的发展方向。FRP因其强度高、耐久性好等特性,近年来被越来越广泛地应用于桥梁等工程领域中。然而,FRP也由于其脆性破坏等原因在应用中受到了一些限制,为了解决这些问题,一些学者开始研究FRP与其他材料的组合构件,使新型构件各组成部分材料的性能得到充分发挥。本文在国内外学者研究的基础上,设计了 1根全GFRP工字梁与6根由不同规格的螺栓连接件锚固的工字型GFRP-混凝土组合梁,并对试验梁的弯曲性能、损伤预警、参数优化等进行了研究。论文的主要研究工作和成果有:1.通过四点弯曲试验,对试验梁的荷载-挠度曲线、荷载-应变关系以及螺栓直径对组合梁承载力的影响、混凝土高度对组合梁刚度的影响等进行了分析。试验结果显示,充分利用GFRP复合材料与混凝土这两种材料各自的性能,可大幅提升结构承载能力;螺栓体积率设置在1%左右,能够较好的满足GFRP与混凝土之间的变形协调;将混凝土梁高与GFRP工字梁高控制在合理的范围内,可防止组合梁发生脆性破坏。2.应用声发射技术对7根梁的加载全过程进行监测,以分形理论为基础,对试验过程中的声发射能量参数时间序列进行相空间重构,并将Matlab编程计算的声发射能量参数时间序列的关联维数值作为定量指标,分析试验梁的损伤规律。研究发现,试验梁关联维数值的变化可以反映GFRP复合材料内部的纤维断裂等损伤演化规律;对于应用GFRP复合材料的结构,可以在剪力较大区域布置声发射传感器,当相应的关联维数值出现“持续高幅波动”,表明结构已达到极限承载力的70%左右,需要引起足够重视并加强监测。3.使用ANSYS软件建立了 GFRP-混凝土组合梁的有限元模型,模型的有效性得到了试验数据的验证,应用该有限元模型进一步对GFRP-混凝土组合梁进行了数值分析。研究表明:FRP级别应该与混凝土强度相匹配,才能更有效发挥两种材料的性能;优化后的的工字型GFRP-混凝土组合梁腹板的剪切挠度系数能够使结构设计更加安全;混凝土截面与GFRP工字型截面的高度比在0.33～0.58范围,是比较合理的截面形式。本文在GFRP-混凝土组合梁合理的螺栓体积率、损伤预警方法以及截面设计的优化高度比等方面的研究,为GFRP-混凝土组合梁的推广应用提供了一定的参考依据。
[Abstract]:Light weight, high strength and durability are the development direction of modern bridge engineering. FRP is more and more widely used in bridge engineering field in recent years because of its high strength, good durability and other characteristics. However, because of its brittle failure and other reasons, FRP has been limited in application. In order to solve these problems, some scholars have begun to study the composite components of FRP and other materials. The properties of each component material of the new type component can be fully developed. Based on the research of scholars at home and abroad, this paper designs a full GFRP I-beam and 6 I-shaped GFRP- concrete composite beams anchored by bolt connectors of different specifications. The bending behavior and damage warning of the test beams are also given. Parameter optimization was studied. The main research work and achievements are as follows: 1. Through four-point bending test, the load-deflection curve, load-strain relationship, the influence of bolt diameter on the bearing capacity of composite beam and the influence of concrete height on the stiffness of composite beam are analyzed. The experimental results show that the load-bearing capacity of the structure can be greatly improved by fully utilizing the properties of GFRP composite and concrete, and the bolting volume ratio is about 1%, which can better meet the deformation coordination between GFRP and concrete. By controlling the height of concrete beam and GFRP I-beam within a reasonable range, the brittle failure of composite beam can be prevented. 2. The whole loading process of 7 beams was monitored by acoustic emission technology. Based on fractal theory, phase space reconstruction of the time series of acoustic emission energy parameters was carried out. The correlation dimension of the acoustic emission energy parameter time series calculated by Matlab is taken as the quantitative index to analyze the damage law of the test beam. It is found that the change of the correlation dimension of the test beam can reflect the damage evolution law of fiber fracture in GFRP composite. For structures with GFRP composite materials, acoustic emission sensors can be arranged in large shear regions. When the corresponding correlation dimension values show "sustained high amplitude fluctuation", it shows that the structure has reached about 70% of the ultimate bearing capacity. Need for adequate attention and enhanced monitoring. 3. The finite element model of GFRP- concrete composite beam is established by using ANSYS software. The validity of the model is verified by experimental data. The numerical analysis of GFRP- concrete composite beam is carried out by using the finite element model. The results show that the FRP grade should be matched with the concrete strength in order to give full play to the performance of the two materials, and the optimized shear deflection coefficient of the I-shaped GFRP- concrete composite beam web can make the structure design safer. The height ratio of concrete section to GFRP I-shaped section is in the range of 0.33 ~ 0.58, which is a reasonable section form. In this paper, the reasonable bolt volume ratio, damage warning method and optimized height ratio of GFRP- concrete composite beam are studied, which provides a certain reference for the popularization and application of GFRP- concrete composite beam.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU398.9;TU317

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