基于混凝土塑性损伤理论的FRP抗剪加固RC梁有限元分析

发布时间：2018-06-11 13:29

本文选题：FRP + 抗剪加固　；参考：《深圳大学》2015年硕士论文

【摘要】：随着土木工程领域既有构件加固需求的增加,纤维增强复合材料(Fiber reinforced plastics,简称FRP)被广泛的应用于混凝土结构的加固工程。FRP材料具有优越的耐腐蚀性、轻质高强便于施工和不影响原有结构截面等优良性质,使其成为重要的加固方式,其中FRP应用于钢筋混凝土梁抗剪加固提高既有混凝土梁的抗剪承载力是加固领域的一项重要课题。在FRP抗剪加固混凝土梁性能研究方面,一些学者进行了试验方面的研究,但由于混凝土梁抗剪性能的复杂性、试验条件的限制、试验者的试验设计局限性等原因造成系统的抗剪数据依然较少。对于影响加固梁抗剪性能的因素大多还停留在单因素的分析层面,而影响FRP抗剪加固混凝土梁性能的因素往往是协同作用,相互影响的。将基于试验的单因素影响规律进行简单叠加并不能很好的反应影响因素对于抗剪性能的影响。伴随着有限元理论发展与成熟,以及计算机软件和硬件的飞速发展,使得运用有限元方法分析FRP加固混凝土梁这一复杂问题成为可能。有限元模拟提供了一种节约时间、经费,不需要考虑试验的限制的研究方法,可以对影响FRP抗剪加固的因素进行有效的分析。本文旨在在混凝土塑性损伤理论的基础上建立一套适用于FRP抗剪加固混凝土梁模拟的有限元模型,为之后的影响因素分析奠定坚实的基础。本文选取六种典型的混凝土塑性损伤模型,对所选取模型的受拉损伤因子和受压损伤因子进行了正交分析。并分别进行了本构模型的横向分析和纵向分析,受拉损伤因子模型对加固梁的抗剪性能具有重要的影响;而受压损伤因子模型的定义对抗剪性能的影响有限影响主要体现在极限荷载后下降段的不同;并通过正交分析的结果选取适用于FRP抗剪加固混凝土梁模拟的混凝土塑性损伤模型。本文建立无腹筋混凝土梁、有腹筋混凝土梁和FRP加固混凝土梁三种有限元模型形成一个模型系统,使得模型循序渐进并在分析中对三种模型进行相互对比。明确了有限元模型在不同类型模型下的规律并进行了不同模型的时程分析。本文对混凝土塑性损伤模型本构定义中对抗剪模拟影响较大的扩容角和粘性系数进行了参数分析,明确了其对抗剪模拟的影响规律并总结了影响扩容角定义的因素。本文同时进行了单元尺寸和界面粘结滑移参数的参数分析。确定了单元尺寸对模拟结果的影响规律及粘结滑移模型对界面定义的重要性,并适当分析了箍筋与FRP条带的相互作用。本文所建立的梁模型的剪跨比基本分布于3左右,属于大剪跨比的混凝土梁。本文之所以选择这些梁进行分析是因为在这一剪跨比附件的试验数据较多并且剪切破坏模式明显,而小剪跨比梁的破坏模式有明显的不同不属于本文的考虑范围。
[Abstract]:With the increasing demand for reinforcement of existing components in civil engineering field, fiber reinforced plastics (FRPs) are widely used in strengthening concrete structures. FRP materials have excellent corrosion resistance. Lightweight and high strength is convenient for construction and does not affect the original structural cross-section and other excellent properties, making it an important way of reinforcement, The application of FRP to shear strengthening of reinforced concrete beams is an important subject in the field of strengthening. In the research of FRP shear strengthening concrete beams, some scholars have carried out experimental research, but due to the complexity of the shear behavior of concrete beams, the test conditions are limited. Due to the limitation of test design, the shear data of the system are still few. Most of the factors affecting the shear behavior of strengthened beams remain at the level of single factor analysis, while the factors affecting the performance of FRP shear strengthened concrete beams are often synergistic and mutually affected. Simply adding the single factor influence law based on the experiment is not a good way to respond to the influence factors on the shear performance. With the development and maturity of finite element theory and the rapid development of computer software and hardware, it is possible to use finite element method to analyze the complex problem of strengthening concrete beams with FRP. Finite element simulation (FEM) provides a time-saving, cost-saving research method that does not need to consider the limitations of the test, and can effectively analyze the factors affecting the shear strength of FRP. Based on the plastic damage theory of concrete, this paper aims to establish a set of finite element models suitable for the simulation of FRP shear strengthened concrete beams, which will lay a solid foundation for the analysis of the influencing factors in the future. In this paper, six typical plastic damage models of concrete are selected and the tensile damage factors and compressive damage factors of the selected models are analyzed by orthogonal analysis. The transverse analysis and longitudinal analysis of the constitutive model are carried out respectively. The tensile damage factor model has an important effect on the shear behavior of the strengthened beam. However, the definition of compression damage factor model has a limited effect on shear performance, which is mainly reflected in the difference of the descending section after ultimate load. According to the results of orthogonal analysis, the plastic damage model of concrete is selected, which is suitable for FRP shear reinforced concrete beam simulation. In this paper, three finite element models of concrete beams without web reinforcement, concrete beams with web reinforcement and FRP strengthened concrete beams are established to form a model system, which makes the models step by step and compare with each other in the analysis. The law of finite element model under different types of models is clarified and the time history analysis of different models is carried out. In this paper, the expansion angle and viscosity coefficient, which have great influence on shear resistance simulation in the constitutive definition of plastic damage model of concrete, are analyzed, the influence law of shear resistance simulation is clarified and the factors influencing the definition of expansion angle are summarized. At the same time, the parameter analysis of element size and interface bond-slip parameters is carried out. The influence of element size on simulation results and the importance of bond-slip model to the definition of interface are determined, and the interaction between stirrups and FRP strips is properly analyzed. The shear span ratio of the beam model is about 3, which belongs to the concrete beam with large shear span ratio. The reason why these beams are selected for analysis in this paper is that there are more experimental data and obvious shear failure modes in this shear span ratio attachment, while the failure modes of small shear span ratio beams are obviously different from the scope of consideration in this paper.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU375.1

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