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近场地震下框架柱抗震性能试验研究.doc

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学校代号 10532 学 号 S07011123 分 类 号 TU03 密 级 硕士学位论文近场地震下框架柱抗震性能试验研究Seismic Performance of Reinforced Concrete ColumnsUnder Near-field Earthquake byLIU YiB.E.(Hunan University)2007A thesis submitted in partial satisfaction of the Requirements for the degree ofMaster of Engineering ScienceinStructural Engineeringin theGraduate SchoolofHunan UniversitySupervisorProfessor YI Weijian May, 20I湖 南 大 学学位论文原创性声明本人郑重声明:所呈交的论文是本人在导师的指导下独立进行研究所取得的研究成果。除了文中特别加以标注引用的内容外,本论文不包含任何其他个人或集体已经发表或撰写的成果作品。对本文的研究做出重要贡献的个人和集体,均已在文中以明确方式标明。本人完全意识到本声明的法律后果由本人承担。作者签名: 日期: 年 月 日学位论文版权使用授权书本学位论文作者完全了解学校有关保留、使用学位论文的规定,同意学校保留并向国家有关部门或机构送交论文的复印件和电子版,允许论文被查阅和借阅。本人授权湖南大学可以将本学位论文的全部或部分内容编入有关数据库进行检索,可以采用影印、缩印或扫描等复制手段保存和汇编本学位论文。本学位论文属于1、保密□,在______年解密后适用本授权书。2、不保密 。□ √(请在以上相应方框内打“√”)作者签名: 日期: 年 月 日导师签名: 日期: 年 月 日□√近场地震下框架柱抗震性能试验研究II摘 要钢筋混凝土柱是混凝土框架主要的抗侧力构件,而框架柱的破坏是引起框架倒塌,并在震后难以修复的主要原因。本文针对近场地震动的特点,对 4 根大比例的钢筋混凝土模型柱进行低周反复荷载试验,在此基础上对钢筋混凝土柱的抗震性能及损伤进行了分析。本文进行了以下几方面的研究:(1) 制定了整体试验计划,完成了试验装置的设计和制作;按照我国现有规范完成了 4 根大比例模型柱的设计和制作,并对钢筋和混凝土进行了材性试验;对一栋按 8度抗震设防的高层框架进行了近场地震动下的非线性时程分析,共选用 PGV/PGA>0.2的近场地震记录 12 条,PGV/PGA0.2 的近场地震记录,不能通过 8 度罕遇地震下的弹塑性验算;根据混凝土框架柱近场地震动下位移时程曲线的特点,制定出了具有近场地震特点的加载制度,同时制订了详尽的试验测量方案。(2) 共对四根钢筋混凝土柱进行了低周反复荷载试验,P-1 模型柱主要用于验证试验装置的可靠性;L-1 模型柱按标准加载制度加载,用于考察按现有《建筑抗震设计规范》GB 50011-2001 设计的混凝土柱的延性; L-2 和 L-3 模型柱分别按考虑近场地震特点的加载制度加载和按传统加载制度加载,用于考察不同加载制度对钢筋混凝土柱抗震性能的影响;着重分析了 L 系列三根柱在低周反复荷载下的骨架曲线、刚度退化和耗能能力等滞回性能,加载制度的变化对抗震性能和塑性铰长度的影响,箍筋应变分布以及截面的约束应力,得到了以下结论:a.L-1 柱的极限层间位移角为 3%,位移延性为 4.47,按现有规范设计的框架柱在近场区域延性储备不足;b.L-3 柱过峰值位移后的小位移对应的平均割线刚度基本和峰值位移对应的平均割线刚度的相近,随着加载位移幅值的减小,平均割线刚度有略微的增加,与 L-2 柱的平均割线刚度相比,非峰值位移所对应的割线刚度明显小于 L-2 模型柱,但是峰值位移对应的割线刚度 L-2 柱和L-3 柱基本一致,这说明峰值位移对应的割线刚度与峰值位移出现的先后无关;c. 累积耗能能力与峰值位移出现的先后次序无关;d.塑性铰区域箍筋最大应变一般出现在离基座一半截面高度的地方;e.由于截面偏心受压的原因,截面两侧的箍筋应力很难同时达到屈服强度,所以按照 J.B.Mander 公式计算的截面约束应力,可能会高估实际的截面约束应力;f. 塑性铰长度依赖于极限位移,所以按照本文制订的加载制度加载的 L-2 和L-3 模型柱的塑性铰长度明显小于经验公式计算值,但是 L-2 和 L-3 模型柱的计算塑性铰长度一致,这说明峰值位移出现的次序对塑性铰长度没有影响。(3) 研究了 Park-Ang 混凝土损伤模型对本文试验损伤评估的准确性,对比结果硕士学位论文III表明:虽然尽量采用了 L-1 模型柱的试验结果确定 Park-Ang 混凝土损伤模型中的参数,但仍难对 L-2 和 L-3 钢筋混凝土模型柱试验中的损伤发展过程进行比较准确的评估;其根本原因是 Park-Ang 混凝土损伤模型中模型参数很难准确的确定,而且损伤模型不能考虑加载制度的变化;还考察了混凝土柱关键截面的横向变形与结构损伤的关系,分析表明,横向变形能比较好的反映出钢筋混凝土柱剪切破坏、纵筋屈曲破坏和混凝土压溃破坏的损伤发展过程。关键词:钢筋混凝土柱;低周反复荷载试验;近场地震;滞回曲线;累积损伤;耗能能力;损伤模型近场地震下框架柱抗震性能试验研究IVAbstractIn frame structures, reinforced concrete columns are important members to resist lateral loads. The damage of the RC columns, which is difficult to be repaired after earthquake, is a major cause of the collapse of the RC frame. According to the features of the near-field earthquake, low cyclic loading experiments were carried out on 4 large scale RC column models. Based on the results, the anti-seismic property of RC column and its damage are analyzed. The research work of this paper could be summarized as the following:(1) Devised the entire test schedule and deployment, designed and assembled the test equipments. In accordance with the present national code, designed and constructed 4 large scale RC column models, conducted the material property test of the steel bar and concrete used, and finished the nonlinear time-history analysis of a high rise frame which is designed to resist the 8th degree earthquake intensity. In the analysis, there are in total 20 near-field earthquake wave records used. 12 among them have their PGV/PGA>0.2, and the other 8 have their PGV/PGA0.2, 92% of the frame failed to meet the standard in the 8th degree rare earthquake elastic-plastic verification. Based on the features of the time-history curve of the RC columns in near-field earthquake, devised the loading policy and measuring policy in detail accordingly.(2) Low cyclic repeated loading tests were conducted on 4 RC columns in total. P-1 model column was used to confirm the reliability of the test equipments. L-1 model column was loaded following the standard loading policy. It was used to examine the ductility of the RC column designed according to the current code for seismic design of buildings GB 50011-2001. L-2 and L-3 model columns were loaded respectively according to the loading policy taking into consideration of the near-field earthquake features and the traditional loading policy. They were used to distinguish the influence of loading policy on the anti-seismic property of RC columns. The paper exhaustively analyzed the hysteresis properties of the 3 L series RC columns, such as their skeleton curve, deterioration of stiffness and energy dissipation. The paper also investigated the influence of loading policy on the anti-seismic property of the columns and on the length of the plastic hinge in the members, considering the strain distribution of the stirrup and the lateral pressure. It is concluded that: (1) The ultimate inter-story displacement angle is 3% in the L-1 test, and the displacement ductility is 4.47. 硕士学位论文VTherefore, in view of the current code, the frame column does not have enough ductility storage in the near-field earthquake; (2) The average secant stiffness of the L-3 column corresponding to the small displacement after the peak displacement approximate that of the peak displacement. With the decrease of the displacement loading amplitude, the average secant stiffness rose a little. Compared with the average secant stiffness of the L-2 column, the non-peak displacement average secant stiffness is remarkably smaller. (3) Accumulative energy dissipation ability has nothing to do with the sequence of the peak displacement. (4) The maximum strain of the stirrup in the plastic zone generally appears half the cross section height near the pedestal. (5) Because of the eccentricity of the cross sectional internal force, the stress of the stirrup on each side of the cross section can not reach yield stress at the same time. Therefore, the cross sectional restrictive force calculated according to the J.B.Mander formula may have been overestimated. (6) The length of the plastic hinge depends on the ultimate displacement. Hence, the lengths of the plastic hinge in L-2 and L-3 columns loaded according to the loading policy stipulated in this paper are significantly less than that calculated from the experience-based formula.(3) Researched the accuracy of the Park-Ang concrete Damage Model with respect to the assessment of the test damage discussed in this paper. The comparison shows that though the parameters in the damage model were obtained from the test result of the L-1 model column, it is still difficult to make an accurate assessment of the damage development in the L-2 and L-3 RC column models. The fundamental reason is the Park-Ang damage model parameters is difficult to be accurately determined, but it dose not account for the loading policy. This paper also investigated the relationship between the lateral deformation of the key cross sections of the RC columns and the structural damage, the result shows that lateral deformation is a good indicator of RC column shear damage, buckling damage of longitudinal steel bar and concrete collapsing damage.Key Words: Reinforced concrete columns; Low cyclic loading experiments; Near-field earthquake; Hysteretic curve; Damage model近场地震下框架柱抗震性能试验研究VI目 录学位论文原创性声明 .................................................................................................................I摘 要 ..........................................................................................................................................IIAbstract.....................................................................................................................................IV第 1 章 绪论...............................................................................................................................11.1 选题的背景及意义..............................................................................................................11.2 混凝土框架柱在地震中的主要破坏形态..........................................................................21.2.1 双向地震作用导致角柱破坏 ......................................................................................21.2.2 结构薄弱层柱上下两端形成塑性铰并引起结构倒塌 ..............................................31.2.3 柱中部压屈破坏 ..........................................................................................................41.2.4 短柱剪切破坏 .............................................................................................................41.2.5 由于变形滞后导致柱端破坏 .....................................................................................51.3 近场地震的定义与主要特征..............................................................................................51.3.1 近场地震的定义 ..........................................................................................................51.3.2 近场地震的主要特征 ..................................................................................................51.4 相关课题的研究现状..........................................................................................................61.4.1 混凝土柱抗震性能试验研究 ......................................................................................61.4.2 混凝土结构损伤模型 ..................................................................................................61.4.3 近场地震下反应谱的特性分析 ..................................................................................91.4.4 研究现状总结 ............................................................................................................101.5 本文研究的目的及内容....................................................................................................101.5.1 研究目的 ...................................................................................................................101.5.2 研究内容 ...................................................................................................................11第 2 章 近场地震下混凝土柱抗震性能试验设计.................................................................122.1 概述....................................................................................................................................122.2 模型柱设计........................................................................................................................132.3 模型柱材料的力学特性....................................................................................................142.4 试验装置............................................................................................................................162.5 加载方式的确定................................................................................................................192.5.1 结构模型 ...................................................................................................................192.5.2 近场地震波的选取 ...................................................................................................202.5.3 非线性时程分析方法 ...............................................................................................21硕士学位论文VII2.5.4 结构时程分析结果 ...................................................................................................212.5.5 低周反复试验加载制度的确定 ................................................................................212.6 试验数据的测量................................................................................................................24第 3 章 近场地震下混凝土柱抗震性能试验结果分析.........................................................273.1 概述....................................................................................................................................273.2 试验现象及模型柱的破坏形态........................................................................................273.2.1 P-1 模型柱 ..................................................................................................................273.2.2 L-1 模型柱 ..................................................................................................................283.2.3 L-2 模型柱 ..................................................................................................................293.2.4 L-3 模型柱 ..................................................................................................................293.3 试验数据分析....................................................................................................................293.3.1 骨架曲线 ...................................................................................................................293.3.2 刚度退化 ...................................................................................................................303.3.3 滞回性能 ...................................................................................................................323.3.4 滞回耗能 ...................................................................................................................333.3.5 应变分析 ...................................................................................................................343.3.6 截面约束应力分析 ....................................................................................................383.3.7 塑性铰长度分析 .......................................................................................................413.3.8 变形分量分析 ...........................................................................................................443.4 本章小结............................................................................................................................47第 4 章 钢筋混凝土柱的损伤分析.........................................................................................484.1 概述....................................................................................................................................484.2 混凝土材料特性及其损伤特点........................................................................................484.3 钢筋的材料特性及其损伤特点........................................................................................484.4 钢筋混凝土柱的破坏主要形态........................................................................................494.5 钢筋混凝土柱损伤定量评估方法....................................................................................494.6 L 系列柱试验结果与损伤分析比较 .................................................................................504.7 柱截面横向变形................................................................................................................544.8 截面横向变形评估损伤的适用性....................................................................................574.9 本章小结............................................................................................................................58结论与展望...............................................................................................................................59参考文献...................................................................................................................................61致谢...........................................................................................................................................64
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