嵌入式预应力CFRP布加固RC箱形梁的力学特性试验研究

发布时间：2018-02-24 18:33

本文关键词： 嵌入式预应力 CFRP加固箱梁试验研究极限承载力　出处：《兰州交通大学》2014年硕士论文　论文类型：学位论文

【摘要】：碳纤维布加固技术由于拥有良好的技术优势，在结构加固方面得到了较快的发展及应用。表层嵌入式预应力加固是CFRP布加固技术最新的发展方向，其兼具嵌入式加固技术及预应力加固技术的众多优点。而混凝土薄壁箱梁由于具有良好的受力性能，在桥梁工程尤其在铁路中小跨径简支梁桥上得到了大量的应用，在长期运营中各种因素引起的钢筋混凝土薄壁箱梁开裂、承载力下降等影响着箱梁的耐久性，采用有效的加固方式提高箱梁的承载力及耐久性显得尤其重要。本文结合甘肃省自然科学基金项目《预应力碳纤维加固钢筋混凝土箱梁的界面应力研究》，在对碳纤维加固技术现阶段的研究成果进行分析总结的基础上，采用嵌入式预应力CFRP布加固技术对RC箱梁进行了抗弯加固，并对其进行了试验研究、理论分析及数值模拟。为此，本文开展了如下几个方面的工作： (1)采用自行研制的碳纤维布预应力张拉锚固装置，对工程中最常见的单箱单室钢筋混凝土简支箱梁进行嵌入式预应力CFRP布抗弯加固，考察了加固试件的破坏模式、受力性能、截面应变分布和挠度变形规律等。试验结果表明采用表层嵌入式预应力加固技术，能够显著的提高试件的抗弯极限承载能力，改善试件的内力和变形分布。 (2)考虑箱梁的剪力滞效应，将翼缘的正应变按N次抛物线分布考虑，在应用剪滞效应的变分法分析结果的基础上，按弹塑性极限强度准则推导了加固后的箱梁在不同破坏模式下的承载力计算公式，弥补了现有规范中关于箱形截面加固梁计算公式的不足。分析了加固后箱梁的两种界限破坏，提出了根据加固量判断最终破坏模式的方法。计算结果表明，，本文所提出的理论计算公式具有较高的可信度，其计算值与试验结果吻合较好。 (3)根据非线性有限元理论，建立了嵌入式预应力碳纤维布加固钢筋混凝土简支箱梁试验的有限元分析模型，对有限元计算结果与试验结果进行了对比分析。
[Abstract]:Because of its good technical advantages, CFRP reinforcement technology has been rapidly developed and applied in structural strengthening. The surface embedded prestressing reinforcement is the latest development direction of CFRP reinforcement technology. The concrete thin-walled box girder has been widely used in bridge engineering, especially in railway small and medium-sized span simply supported girder bridge, because of its good mechanical performance. The cracking and bearing capacity of thin-walled reinforced concrete box girder caused by various factors in long-term operation affect the durability of box girder. It is very important to improve the bearing capacity and durability of box girder by using effective reinforcement method. In this paper, the interface stress of reinforced concrete box girder strengthened with prestressed carbon fiber is studied in the light of Gansu Natural Science Foundation project. On the basis of the analysis and summary of the current research results of fiber reinforcement technology, The flexural strengthening of RC box girder is carried out with embedded prestressed CFRP cloth, and the experimental research, theoretical analysis and numerical simulation are carried out. For this reason, the following work is carried out in this paper:. 1) using the prestressing tensioning and anchoring device developed by ourselves, the most common single box single chamber reinforced concrete simply supported box girder is strengthened with embedded prestressing CFRP cloth, and the failure mode and mechanical performance of the strengthened specimen are investigated. The experimental results show that the ultimate bearing capacity of the specimens can be significantly improved and the internal force and deformation distribution of the specimens can be improved by using the surface embedded prestressing reinforcement technology. (2) considering the shear lag effect of box girder, the normal strain of flange is considered according to N parabola distribution, and based on the results of the variational analysis of shear lag effect, According to the ultimate elastoplastic strength criterion, the formulas for calculating the bearing capacity of the strengthened box girder under different failure modes are derived, which make up for the deficiency of the calculation formula of the box section strengthened beam in the existing code. Two kinds of boundary failure of the strengthened box girder are analyzed. The method of judging the ultimate failure mode according to the reinforcement quantity is put forward. The calculation results show that the theoretical formula presented in this paper has a high reliability and the calculated value is in good agreement with the experimental results. According to the nonlinear finite element theory, the finite element analysis model of reinforced concrete simply supported box girder strengthened with embedded prestressed carbon fiber sheet is established, and the finite element calculation results and test results are compared and analyzed.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441;U445.72

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