【作者】 辛力；

【导师】 梁兴文；

【作者基本信息】 西安建筑科技大学 ， 结构工程， 2009， 博士

【摘要】 基于性能/位移的抗震设计理论自20世纪90年代提出以来,受到广泛关注,被认为是未来结构抗震设计的发展方向。在抗震结构中,剪力墙作为主要的抗侧力构件,通常为第一道抗震防线,其抗震性能的优劣对整个房屋的抗震性能影响很大。近年来,随着经济和技术的发展,高性能混凝土剪力墙已被普遍应用于高层及超高层建筑结构中,但是由于高性能混凝土的脆性以及剪力墙本身变形能力较差的特点,其使用范围受到严格限制。对高性能混凝土剪力墙基于位移的抗震设计方法进行研究,可很好地解决高性能混凝土剪力墙强度高而变形能力较差的矛盾,扩大高性能混凝土剪力墙的使用范围,具有重要的理论意义和实用价值。本文简要介绍了基于性能/位移的抗震设计理念、研究现状及研究成果,论述了考虑高振型影响的直接基于位移的抗震设计的基本方法及设计过程。在以往研究基础上,以我国现行抗震设计规范的相关规定为基础,着力解决高性能混凝土剪力墙直接基于位移的抗震设计中的以下几个问题:(1)剪力墙抗震性能研究及性能指标的确定。通过对5片剪跨比分别为1.5和1.0的高性能混凝土剪力墙试件低周水平反复荷载试验,研究了中高、低矮高性能混凝土剪力墙的破坏形态、破坏机理及变形性能,验证了分段约束配箍方式对于提高弯曲型剪力墙变形能力的有效性,说明了剪力墙截面变形能力设计方法在一定程度上的可靠性,论证了剪力墙塑性铰转角与其破坏程度有较好的相关性。根据墙体不同阶段的破坏程度,将剪力墙结构的性能划分为“使用良好、保证人身安全和防止倒塌”三个水平,提出用层间位移角和塑性铰转角共同作为剪力墙结构的性能控制指标,并给出了三性能水平的建议值。(2)剪力墙弹塑性分析的宏观墙元模型。以结构三维非线性分析程序CANNY为平台,采用纤维墙元模型对剪力墙进行非线性分析。通过对4片剪力墙试件的非线性仿真分析,并与试验结果对比,说明了这种墙元模型的有效性。(3)考虑高阶振型效应的静力弹塑性分析方法。在模态Pushover分析方法中,用能力谱法替代原有的动力时程分析,在现行规范加速度反应谱基础上计算结构各振型等效单自由度体系各性能水平的位移反应,然后将其转化为相应多自由结构的位移反应,并通过SRSS法求得结构的总位移反应,用其与剪力墙的目标位移进行比较,判断设计结果是否满足性能目标要求。(4)剪力墙弹性刚度的选取。提出一种“目标周期法”,即由剪力墙各性能水平的目标位移导出其相应等效周期(目标周期),以结构各性能水平自振周期小于或等于目标周期为原则确定墙肢的截面厚度,使剪力墙的能力曲线与需求曲线在弹性阶段基本重合,抗震能力基本等于抗震需求。(5)剪力墙承载力设计值的确定。研究了高性能混凝土剪力墙超强系数的取值,提出了超强系数的取值方法;将结构各性能水平地震需求的最大值除以超强系数得到剪力墙的承载力设计值,并以此为依据进行剪力墙截面承载力设计,使剪力墙的能力曲线在弹塑性阶段不低于需求曲线,确保剪力墙满足各性能水平的承载力需求。(6)剪力墙斜截面受剪承载力计算。根据收集到的313片剪力墙试件的受剪性能试验数据,分析了中国混凝土规范、美国ACI规范及桁架-拱模型所给的剪力墙受剪承载力计算公式的可靠性和拟合效果,探讨了剪力墙受剪承载力的主要影响因素及其相互关系。在此基础上,根据试验数据重新拟合能够适应不同计算理论的剪力墙受剪承载力计算公式。为我国现行规范剪力墙受剪承载力计算公式的进一步修正提供参考。(7)基于塑性铰转角需求的剪力墙截面变形能力设计方法。以性能目标要求的剪力墙极限塑性铰转角需求作为设计基准,建立了剪力墙塑性铰转角、轴压比、边缘构件约束区长度以及配箍特征值的关系,针对目前我国规范设计现状,提出了较合理的剪力墙轴压比限值及边缘构件设计方法。以上各内容包含了剪力墙的性能目标确定、弹性刚度选取、承载力设计、变形能力设计以及静力弹塑性分析验证,概括了剪力墙直接基于位移的抗震设计全过程。最后将各问题串联,通过一算例分析介绍了本文所给方法的设计全过程,为剪力墙类结构直接基于位移的抗震设计提供了一个可供参考的思路和方法。更多还原

【Abstract】 Performance/Displacement-based Seismic Design theory,which was put forward in 1990s,has been receiving considerable attentions,and it is regarded as the development direction of seismic design theory in the future.In the seismic fortification system of structure,shear walls are the prime lateral force-resisting elements and it is used as the first seismic fortification line generally.The seismic behavior of shear walls has a significant effect on the seismic behavior of the whole structure.In recent years,high performance concrete shear walls are used in tall buildings or super tall buildings widely, but the application scope of high performance shear walls is restricted because of the brittle character of high performance concrete and shear walls.Study on the displacement-based seismic design method of high performance concrete shear walls can improve the deformation capacity of high performance concrete shear walls to some extent,enlarge the application scope of high performance concrete shear walls,has important theoretical significance and practical value.In this paper,Performance-based Seismic Design(PBSD) methodology is briefly introduced.The basic methodology and corresponding design procedure of Direct Displacement-based Seismic Design(DDBSD) are emphasized.Based on previous research achievements,it manages to solve some problems in the process of DDBSD method of high performance concrete shear walls,and it will make this new design method more practical for shear-wall structures.The main content is presented as follows:(1) The performance objective of high performance concrete shear walls.Based on the tests of 5 high-performance concrete shear walls which shear span ratios are 1.5 and 1.0,the failure mode,failure mechanism and deformation capacity of medium-high and low-rise shear walls are studied.The new reinforcement method of several rings like a chain along boundary element in plastic hinge zone is verified to improve the deformation capacity of shear walls effectively,it shows that the deformation capacity design method of shear wall is reliable to a certain extent,and it indicates that the rotation of plastic hinge zone is related to the damage level of shear walls well.According to the damage level,the performance of shear wall structure is divided into three levels: "serviceability,life-safety and collapse-prevention",the storey drift ratio and the plastic hinge rotation are both used as the performance controlling indicators of shear wall structures,and the proposed values for each performance level are provided in this paper.(2) The macro model for high performance concrete shear walls’ nonlinear analysis.The fiber wall element model in CANNY program is used to analyze the shear wall’s non-linear performance.4 shear wall specimens’ analysis results are very agreement with their test results,and it proves that the fiber wall element model is reasonable and efficient in the nonlinear analysis of shear walls.(3) Pushover analysis procedure considering higher mode effect.In the procedure of modal pushover analysis,the capacity spectrum theory is used to take the place of dynamic time-history analysis.Converting the acceleration response spectrum of current code into displacement response spectrum,the displacement response of ESDOF in each mode can be calculated by capacity spectrum method.Then the displacement response of MDOF can be obtained too,and it is used to compare with the objective displacement of each performance level,judging whether the structure satisfying its performance objective or not.(4) The reasonable elastic stiffness of shear walls.The structural target period in "serviceability" is deduced by its target displacement based on the displacement response spectrum."Target period" method that demands the natural periods should be smaller than or equal to corresponding target periods is used to select the section rigidity of shear walls.It can ensure that the capacity curve in elastic range is in agreement with the demand curve,and the seismic capacity equals to the seismic demand basically.(5) The design bearing capacity of shear walls.The bearing capacity demand of each performance level is determined by the target displacement and corresponding elasto-plastic displacement response spectrum,and the maximum is regarded as the structural bearing capacity demand.The over-strength coefficient of high performance concrete shear walls designed by Chinese code which is defined as the ratio of actual bearing capacity to design bearing capacity is discussed,and the bearing capacity demand divided by over-strength coefficient equals to the design beating capacity which ensures the structure meeting its performance objective in inelastic stage.(6) The calculation method for shear capacity of shear walls.Based on 313 test data of shear capacity of RC shear wall,the paper analyzes the reliability of calculation method for shear capacity of shear wall proposed by Chinese code,ACI code and truss-arch model.Some influencing factors of the shear capacity of RC shear wall are discussed,and the calculating equations of shear capacity of RC shear wall are rebuilt adopting mathematical statistics method.It provides a valuable thought to the modifying of current code.(7) The plastic hinge rotation-based design method of shear walls’ deformation capacity.The relationship between plastic hinge rotation and cross section’s curvature, axial load ratio and relative height of compression zone are deduced.The length of confined zone can be determined by plane-section assumption theory,and the transverse reinforcement characteristic value is determined by the stress-strain relationship of confined concrete.The length of confined zones and the transverse reinforcement characteristic values of boundary element in different seismic grades and axial load ratios are proposed.The paper illustrates the application of the proposed procedures above mentioned with an example and attempts to prove its feasibility.It provides a valuable thought to DDBSD method of high performance concrete shear wall structures.更多还原