【作者】 符怡；

【导师】 计欣华；

【作者基本信息】 天津大学 ， 固体力学， 2008， 博士

【摘要】 本文针对碳纤维加固混凝土结构的若干力学问题进行了多方面的研究。研究工作主要从理论及实验两方面开展,涉及的内容包括碳纤维材料本身的力学性质、碳纤维与混凝土粘结界面的力学特点、碳纤维对裂纹扩展的影响等几个方面。首次将数字图像频域分析法(DIAF)应用于该领域的试验研究中。首先,本文介绍了数字图像频域分析法的基本原理,首次分析了将其应用在混凝土构件试验研究中存在的一些问题,包括混凝土自然表面与喷斑处理过表面对测试精度的影响及表面缺陷对测试精度的影响,给出了针对刚体位移、过大位移的处理方法,确立了如何解决系列加载中涉及到的位移叠加位置不匹配问题的方法,并对数字图像频域分析法应用在混凝土构件试验研究中位移、应变的测试精度进行了分析。其次,采用基于统计失效模型的方法,建立了一个基于单元的含有剪切面参数的三维剪滞模型,从细观力学的角度对CFRP片材的拉伸力学性能进行了数值模拟。纤维的强度基于蒙特卡洛(Monte.Carlo)方法,用两参数的韦布尔(Weibull)分布模拟。通过对碳纤维片材的数字图像频域分析法的试验研究证明了数值模拟的正确性。本文引入与横向剪切变形相关的界面应力σ_p ,τ_p,推导了考虑横向剪切变形影响的CFRP加固混凝土三点弯梁界面剪应力及剥离正应力的解析解。以此为基础,结合数字图像频域分析法对CFRP加固混凝土三点弯梁界面位移场进行光力学试验研究,得到了碳纤维片材粘贴端部界面剪应力与滑移量之间的关系曲线。作为对CFRP加固结构界面力学性能的补充研究,本文还对轴向拉伸铝试件粘贴CFRP后界面的变形情况进行了实验研究。以混凝土和CFRP片材的本构关系和变形特征为分析的基础,通过考察含裂纹的CFRP增强混凝土三点弯梁开裂的横截面的静力平衡关系,建立了承载力的理论解。与此同时,通过数字图像频域分析法,对CFRP增强含裂纹混凝土梁三点弯加载下裂纹尖端的位移场、应变场进行实验研究,较精确地获得了裂尖张开位移与荷载之间的关系曲线。更多还原

【Abstract】 This article should carry out multiphase study for some mechanical problems in strengthening concrete structure with carbon fibre. The research mainly begins from the both sides, that is theory and practice, the concerned contents include such aspects as the in-house mechanical property of carbon fibre material, the mechanical characteristic of the bonding interface between carbon fibre and concrete, and the impact on crackgrowth by carbon fibre. Digital image analysis in frequency(DIAF)is applied to experimental study of this field for the first time.Firstly ,some problems existent in the application, of digital image analysis in frequency, to the experimental study of concrete component are analyzed, including such problems as the impact on measuring accuracy by concrete natural surface and sprayed surface and as the impact on measuring accuracy by surface defect, a processing method was presented aiming at rigid body displacement and oversized displacement,the solving method was given for such problems as displacement superposition and mismatching position in series loading,and the measuring accuracy for displacement and deformation is analyzed when digital image analysis in frequency is applied to concrete component experimental studyA module based 3-D shear-lag mode with the parameters of shear surface is set up through the method of statistic failure mode, and the numerical simulation for stretching force performance of CFRP plate is carried out completely and correctly from the aspect of mesomechanics. The toughness of fiber is based upon Monte Carlo method,and the double-parameter Weibull distribution simulation is adopted. Through the experimental study for the frequency domain correlation analysis method of the digital image of carbon fibre sheet material, the correctness of numerical simulation is proved.Interfacial stressσ_p ,τ_p correlative with transverse shear distortion is introduced, and the analytic solution for shear stress and peel normal stress of tri-point curved beam interface of CFRP strengthening concrete with the consideration of distortion effect of transverse shear. Taking this as a base and combining correlation analysis method of digital image frequency domain, photodynamics experimental study is made for displacement field of tri-point curved beam interface of CFRP strengthening concrete, and the relation curve, between shear stress and slippage, of plastering head end of carbon fibre sheet material. As a supplementary study of the mechanical property of CFRP reinforced structure interface, this article also carried out experimental study for interfacial distortion of axial tension aluminium specimen after plastering CFRP.The theory resolution of bearing capacity is found through researching the static equilibrium relation of the fissured cross section of concrete tri-point curved beam with CFRP strengthening by taking the constitutive relation and deformation behavior of concrete and CFRP plate as the base. In the meanwhile,through correlation analysis method of digital image frequency domain and through the experiment study of the displacement field and strain field of the crack tip of load tri-point curved beam of crackled concrete beam with CFRP strengthening, the relation curve between the tension displacement of fissured tip and load is obtained rather accurately.更多还原