【作者】 孙治国；

【导师】 郭迅；

【作者基本信息】 中国地震局工程力学研究所 ， 结构工程， 2012， 博士

【摘要】 国内外近期发生的破坏性地震如1989年美国Loma Prieta地震、1994年美国Northridge地震、1995年日本Kobe地震、1999年我国台湾Chi－Chi地震和2008年我国汶川大地震，均对桥墩造成了严重震害。开展钢筋混凝土桥墩抗震问题的研究，对保证桥梁结构抗震安全和交通生命线畅通，具有十分重要的意义。确保桥墩在大震下具有良好的延性和耗能能力，是实现桥梁结构基于位移/性能抗震设计的重要前提。本文基于大量试验结果的分析，结合拟静力试验和数值模拟手段，对采用普通和高强钢筋混凝土材料的实心和空心钢筋混凝土桥墩抗震变形能力进行了若干研究，具体包括桥墩延性变形能力及位移相关塑性铰区约束箍筋用量、普通及高强钢筋混凝土墩柱等效塑性铰长度、薄壁空心墩抗震拟静力试验、空心墩变形能力和桥墩弯剪数值分析模型等，主要工作和认识如下：1.为研究钢筋混凝土桥墩的延性变形能力和配箍要求，收集整理了国内外进行的234根实心桥墩的抗震拟静力试验数据，基于试验结果对现有桥梁抗震规范保证桥墩延性变形能力的可靠性进行了评价，通过回归分析建立了弯曲破坏桥墩变形能力的表达式；分别以2%和3%极限位移角为设计目标，提出了适用于普通及高强钢筋混凝土桥墩的位移相关塑性铰区约束箍筋用量计算公式并进行了验证。2.为评价高强钢筋和混凝土材料的应用对桥墩等效塑性铰长度的影响，收集整理了国内外进行的108根普通及高强钢筋混凝土墩柱等效塑性铰长度试验结果，评价了国内外主要桥梁抗震规范中等效塑性铰长度计算公式的可靠性。通过回归分析讨论了影响墩柱等效塑性铰长度的主要因素并提出了新的表达公式。认为钢筋混凝土墩柱等效塑性铰长度主要与试件高度、加载方向截面宽度和纵筋直径有关。3.总结了我国大型桥梁工程中空心桥墩的应用情况，设计了2个矩形薄壁空心墩试件并分别进行了定轴力和变轴力下的抗震拟静力试验。对比分析了试件的破坏过程和最终破坏形态，裂缝宽度，残余位移和抗剪强度等。发现试件倒塌前表现出明显的弯―剪破坏特征，包括弯曲与剪切开裂、混凝土压碎破坏、纵筋屈曲等。由于损伤的逐步累积，试件变形超过2%位移角后，由于薄壁的失稳而引起了突然的倒塌，且变轴力下试件的倒塌破坏更为剧烈。4．在总结国内外进行的空心墩抗震试验结果的基础上，分析了弯曲、弯剪和剪切破坏形态下空心墩的变形能力和主要影响因素，认为矩形空心墩变形能力主要与塑性铰区配箍、纵筋配筋、壁厚和轴压比等因素有关，随箍筋、纵筋配筋和壁厚增加而增加，随轴压比增加而减少。讨论了现有规范对保证空心墩变形能力的可靠性，最后基于Caltrans规范给出了不同极限位移角下空心墩塑性铰区约束箍筋用量设计公式。5.基于纤维单元模型和修正的压力场理论(The Modified CompressionField Theory, MCFT)建立了钢筋混凝土桥墩的弯剪数值分析模型，模型中以纤维模型模拟结构的弯曲变形和极限承载力，以MCFT理论计算桥墩的剪切变形，两者耦合共同考虑桥墩的弯剪作用。最终通过与6个弯剪破坏圆形截面桥墩拟静力试验结果的对比，验证了模型的准确性。更多还原

【Abstract】 The vulnerabilities of reinforced concrete (RC) bridge columns toseismic actions have been repeatly demonstrated in recent events such as theLoma Prieta earthquake (1989), Northridge earthquake (1994), Kobeearthquake (1995), Chi-Chi earthquake (1999), and the Wenchuan earthquake(2008). The research on the seismic performance of RC bridge columns isimportant to ensure the seismic safety of RC bridges and crucial loads, andthe seismic ductility and energy absorption capacity of the RC bridgecolumns are key prerequisites of displacement/performance based seismicdesign of the bridges.Based on analysis of the collected seismic test results for RC bridgecolumns, quasi-static experimental research and numerical simulation, theseismic deformation capacity of solid and hollow bridge columns withnormal and high strength concrete and reinforcement was studied. Whichincluding the ductile deformability and drift based confining reinforcementof the bridge columns, the equivalent plastic hinge length for normal andhigh strength RC bridge columns, quasi-static experiment for thin-walledhollow bridge columns, the seismic deformability of hollow bridge columnsand the flexural-shear seismic analysis model for RC bridge columns. Themain work results and conclusion are summarized as follows:1. To study the seismic deformation capacity and confiningreinforcement for RC bridge columns,234quasi-static test results for solidRC bridge columns were collected, the code provisions for the amount ofconfining reinforcement in the potential plastic hinge region of the bridgecolumns were evaluated via comparing with the test results. The equation forthe deformability of the solid rectangular bridge columns was proposed basedon regression analysis of the collected test results. Then, design equations forconfining reinforcement required to achieve drift ratios of2%and3%of thebridge columns are suggested and verified.2. To assess the influence of using high strength reinforcement andconcrete on the equivalent plastic hinge length of the bridge columns,108testresults of the plastic hinge length for normal and high strength RC bridgecolumns were collected and analyzed, and the code provisions for the plastichinge length in and out of China were evaluated. The main influencing factorson the plastic hinge length of the bridge columns were discussed and a newequation for the plastic hinge length of RC bridge columns is proposed by regression analysis on the collected test results. It is concluded that theequivalent plastic hinge length mainly depending on the specimen length,section width in the loading direction and the diameter of longitudinalreinforcement.3. The application of hollow columns in large bridges in China wassummarized. Two same large-scale hollow RC pier specimens were designedand tested. One specimen was subject to displacement-controlled cyclic lateralloading with a constant axial load, and the other was subject todisplacement-controlled cyclic lateral loading with variable axial load.Behavior of the specimens were evaluated in terms of damage progress andfinal failure pattern, concrete cracking width, residual displacement and shearstrength. Test results revealed that both specimens exhibited a mixedflexure-shear damage mode firstly and exhibited stable hysteretic loops. Thedamage of the column including flexural and shear cracking, crushing of theconcrete, and buckling of the reinforcement. When the top displacementexceeding2%of the pier height, all the specimens collapsed suddenly due tolocal compression flange buckling, and the specimen under variable axial loadcollapsed more severely than the one under constant axial load.4. Based on the collected seismic test results for hollow bridge columns,the seismic deformability of the columns with flexure, flexure-shear and shearfailure modes were studied, the main influencing factors on the deformabilityof the columns were discussed and the code provisions were evaluated. It isfound that the deformation capacity of the hollow bridge piers will beincreased as the transverse reinforcement, longitudinal reinforcement, andweb width increasing, and decreased as the axial load ratio increasing. At last,design equations for confining reinforcement in the potential plastic hingeregion of hollow bridge columns are suggested based on the Caltrans seismicdesign code for bridges.5. A flexure-shear seismic analysis model for RC bridge columns wasproposed based on the fiber element model and the Modified CompressionField Theory (MCFT). In the seismic analysis model, the flexuraldeformation and the ultimate strength of the column were obtained by thefiber element model, while the shear deformation of the column was obtainedby the MCFT. The fiber model and the MCFT coupled to simulate theflexure-shear-axial interaction of the bridge piers. The accuracy of the modelis verified by comparing with quasi-static test results for6circular bridgecolumns with flexure-shear failure modes.更多还原