【作者】 王代玉；

【导师】 吕大刚； 王震宇；

【作者基本信息】 哈尔滨工业大学 ， 结构工程， 2012， 博士

【摘要】 近年来发生的历次地震中，均有大量的钢筋混凝土框架结构由于缺乏足够的延性和耗能能力而产生严重破坏甚至倒塌。这些框架结构大多采用1970年以前的旧规范进行设计，仅考虑了竖向荷载而未进行抗震设计，或由于抗震设计规范的修订而不能满足现行抗震设计规范，此类框架结构即是本文所研究的非延性钢筋混凝土框架。目前我国抗震设防地区存在大量的此类框架结构，其在未来高水准地震作用下存在较高的严重破坏和倒塌风险,因此急需进行抗震加固。近二十年来，纤维增强复合材料(Fiber Reinforced Polymer, FRP)由于其轻质、高强和便于施工的优点，已在混凝土结构的抗震加固领域得到广泛应用。对比日益增多的工程应用，FRP加固非延性钢筋混凝土框架结构抗震性能的研究则明显滞后，各国规范基本未有针对结构层面的抗震加固设计方法，即还未解决针FRP加固钢筋混凝土框架结构的合理加固方案及量化设计的两个关键问题。因此，进行FRP加固非延性钢筋混凝土框架结构的抗震性能的研究，对避免大量非延性框架结构在未来地震作用下发生严重破坏、实现“大震不倒”的抗震设防目标具有重要的理论意义和工程应用价值，为我国建筑抗震设计规范和混凝土结构加固规范的进一步修订奠定基础和提供技术支持。针对目前FRP加固非延性钢筋混凝土框架结构抗震性能研究的不足，本文以材料层面的FRP约束混凝土应力-应变关系研究为切入点，以构件层面的FRP加固钢筋混凝土框架柱抗震性能研究为基础，进行了结构层面的FRP加固钢筋混凝土框架结构整体抗震性能研究，提出了FRP抗震加固非延性钢筋混凝土框架结构的概念设计原则，即解决了合理加固方案的问题，初步实现了基于位移的非延性钢筋混凝土框架结构的FRP抗震加固设计方法，即初步解决了FRP加固用量的问题。主要研究内容如下：(1)在材料层面，开展了FRP约束钢筋混凝土圆柱和方柱的单调受压及反复受压试验，考察了截面形状和尺寸、内部纵筋和箍筋、FRP包裹层数及预设损伤对单轴受压性能的影响规律；基于单调受压试验结果，建立了考虑尺寸效应及FRP和箍筋混合约束作用的单调受压应力-应变关系模型；基于反复受压试验结果，建立了考虑钢筋影响的FRP约束混凝土残余应变和加卸载曲线模型；将建立的单调受压应力-应变模型与加卸载曲线模型结合，建立了具有较高精度的FRP约束钢筋混凝土反复受压应力-应变关系滞回模型；在此基础上，自主开发了用于构件和结构抗震性能分析的基于OpenSees(Open System for EarthquakeEngineering Simulation)分析平台的FRP约束混凝土材料模块；(2)在构件层面，进行了FRP加固足尺钢筋混凝土圆柱和方柱的伪静力试验，探讨了FRP包裹层数、轴压比、截面尺寸和形状对加固柱荷载-位移滞回性能的影响，采用刚度、强度、延性和能量耗散等指标对加固前后柱的抗震性能进行了评价，并基于试验结果，建立了FRP加固钢筋混凝土柱的卸载刚度和有效刚度模型；采用OpenSees软件，基于自主开发的FRP约束混凝土材料模块，实现了FRP加固钢筋混凝土柱荷载-位移滞回抗震性能的精细化数值模拟分析；基于经过验证的FRP加固钢筋混凝土柱有限元建模和分析方法，进行了考虑截面形状和尺寸、轴压比、剪跨比、混凝土强度、FRP包裹层数和配筋率影响的Pushover参数分析，建立了可以用于设计和宏观有限元分析的FRP加固钢筋混凝土圆柱和方柱的荷载-位移恢复力滞回模型；(3)在结构层面，进行了未加固和CFRP加固后的2个四层两跨大比例钢筋混凝土框架结构的振动台试验，基于试验结果考察了加固前后结构的破坏形态、地震响应及抗震性能的变化，探讨了在不同水准地震作用下结构从损伤开始到最终破坏的损伤演化规律；采用OpenSees有限元软件，实现了FRP加固钢筋混凝土框架结构振动台试验的有限元模拟分析，验证了整体结构有限元建模方法的正确性和分析结果精确性；在此基础上，进行了不同高度非延性钢筋混凝土框架结构采用FRP加固前后的弹塑性静力Pushover分析和动力时程反应分析，提出了抗震加固概念设计原则；以加固柱的极限位移角为目标位移，基于建立的加固柱荷载-位移恢复力模型并结合概念设计原则，初步实现了非延性钢筋混凝土框架结构的FRP抗震加固设计方法。更多还原

【Abstract】 In previous earthquake events, it have been reported that a number of existingreinforced concrete (RC) frames experienced severe damage, or even collapsed, dueto insufficient ductility and energy dissipation capacity. Most of these framesdesigned according to pre1970codes which bears gravity loads only, and noneconsidering seismic load, or can not stisfy the present siesmic requirements due tothe revision of design code. All of these RC frames with insufficient can be definedas nonductile RC frames, which is the research object of this study. At persent, thereare a great many of this nonductile RC frames existed in the potential earthquakeregions of our country. All of this nonductile RC frames have a high risk level ofsevere damage or collapses in the furture strong earthquakes. In order to reduce thisrisk, threre is an urgent need to seismic strengthen such existing nonductile frames.Fiber reinforced polymer (FRP) composites have been widely used for sismicstrengthening or rehabilitation of concrete strucutures in the past decades, due totheir light weight, high strength, and ease of application. However, comparing withthe actual application in engineering, the theoretical investigation of seismicperformance of nonductile RC frames strengthened with FRP is obviously laggedbehind. The two key problems of reasonable FRP retrofitted scheme andquantification design are still not solved. At present, there is no seismic designmethod in structural level for RC frmaes retrofitted by FRP. Consequently, theinvestigation of seismic performance and design method of FRP strengthendnonductile RC frames has important theoretical significance and engineering value.It is the basis work that providing technical support for modifieding the seimicdesign code and the strengthen design code for concrete structures of our country.In order to address current research gaps, this thesis firstly on the material levelconducted the investigation of stress-strain behavior of FRP-confined concrete, andthen the seismic performance of FRP strengthened RC columns were studied as thebasic work on member level. Finally, the structural seismic performance of FRPstrengthened nonductile RC frames were investigated, The concept design principlefor FRP seismic retrofitting nonductile RC frames was proposed, so the problem ofhow to determine reasonable FRP retrofitted scheme was solved. Then thedisplacement-based seismic design method for nonductile RC frames retrofittedusing FRP was preliminary proposed, so the problem of how to quantification designthe FRP amount was preliminary solved. The main contents of this thesis aresummarized as follows: (1) On the material level, FRP-confined circular and square RC columns weretested under concentric monotonic or cyclic compression loading regimes, and thenthe influence of cross-sectional shape and size, internal longitudinal and hoop steelreinforcement, number of layers of FRP wrap, and pre-damage level on the axialcompressive behavior of FRP-confined concrete was investigated. Based on the testresults of monotonic loading, the monotonic stress-strian model which consideringsize effect factor and hybrid confinement of FRP and hoops was proposed. Based onthe test results of cyclic loading, the equations of plastic strian and theunloading/reloading paths considering the influence of internal steel reinforcementwere also proposed. Combined with the monotonic stress-strian model and theunloading/reloading model, the cyclic stress-strian model for FRP-confinedreinforced concrete was finally developed. Then the proposed stress-strain modelwas added to the OpenSees software as a uniaxial FRP-confined concrete materialwhich can be used to analysis the seismic behavior of FRP strengthend RC membersand structures.(2) On the member level, quasi-static test of FRP strengthend full scale RCcolumns were conducted firstly. The influence of number of layers of FRP wrap,axial compression ratio, and cross-sectional size on the lateral load-displacementhysteretic behavior of strengthened columns was studied, and the seismicperformance of the RC columns before and after strengthend was evaluated usingthe parameters of stiffness, strength, ductility and energy dissipation. Based on thetest results, the expressions of unloading stiffness and effective stiffness for FRPstrengthened circular and square RC columns were proposed. Analytical simulationof lateral load-displacement hysteretic behavior of FRP strengthened RC columnswas conduceted using OpenSees and the added FRP-confined concrete material. Thesimulation results agree well with test results. On the basis, the Pushover analysiswas conducted considering the influence parameters of cross-sectional shape andsize, aixal compression ratio, shear span ratio, concrete strength, number of layers ofFRP wrap, and steel reinforcement ratio. Then the lateral load-displacementhysteretic models for FRP strengthened circular and suqare RC columns wereproposed. The model can be used to seismic design and analysis of FRP strengthendcircular and square RC columns.(3) On the structural level, shaking table test of4storeys and2bays bare andFRP strengthened nonductile RC frames was conducted to investigate the variationof failure mode, seismic response and performance between bare and FRPstrengthened frames, and the development process from initial damage to failure ofstructures under different eathquake levels was also discussed. Then the finite element model of shaking table specimen and nonlinear dynamic analyses wereconducted using OpenSees software. The simulation results agreeing well with testresults show the correctness of modeling approach and accuracy of analysis results.On the basis, the seismic performance of nonductile RC frames with differentheights and strengthened using three FRP rehabilitation schemes were evaluatedanalycitcally. Nonlinear static Pushover and time history analysis were conductedfor the studied cases. The concept design principle for FRP seismic retrofittingnonductile RC frames was proposed from the analyzing of analytical results.Combined with the seismic concept design principle and the lateralload-displacement hysteretic model of FRP strengthened columns, using the ultimatedrift ratio of FRP strengthened columns as the target diaplacement of structural,preliminary proposed the displacement-based seismic design method for FRPseismic strengthend nonductile RC frames.更多还原