速度脉冲强震下偏心RC框架结构抗震设计法的基础研究

发布时间：2018-09-01 07:58

【摘要】：结构偏心布置和近断层速度脉冲地震作用是结构抗震设计中两种极为不利的条件。本文将以往单独考虑的这两种条件综合,研究偏心钢筋混凝土(RC)框架结构在速度脉冲地震作用下的抗震需求和设计方法。针对目前研究的不足,本文的目的是在开发考虑轴力-弯矩相互作用恢复力模型的基础上,量化研究偏心RC框架结构在速度脉冲强震作用下的抗震需求,提出其延性折减系数的修正方法,从而建立偏心结构基于强度折减系数的抗震设计方法。本文主要开展了以下几个方面的研究工作:(1)开发轴力-弯矩相互作用模型(N-M模型)。基于VC++平台和金属塑性原理,开发考虑轴力-弯矩相互作用的恢复力模型。通过对有实际震害记录的RC框架结构模型和一超高层建筑结构的分析,评估N-M模型的有效性和计算效率。结果表明,N-M模型在结构弹塑性分析中能获得较为可靠的结果,且计算效率较纤维模型或多弹簧模型大为提高。N-M模型能为批量计算或超大规模结构分析提供高效途径和验证手段,可在科研和工程中加以应用和完善。(2)研究速度脉冲强震作用下单层偏心结构的抗震需求。揭示不同偏心形式和轴力对结构抗震需求的影响机理,探讨最佳强度中心和刚度中心相对位置。分别研究基于N-M模型的单层偏心RC剪力墙和框架结构在速度脉冲地震作用下的弹性和弹塑性抗震需求变化规律。结果表明,单层偏心RC剪力墙和框架结构在速度脉冲强震作用下均比非速度脉冲地震作用下有更大的弹性和弹塑性抗震需求。进入弹塑性阶段后,速度脉冲效应和偏心效应两者存在耦合影响。轴力对弹性抗震需求无影响,但对弹塑性抗震需求有一定影响。三种不同偏心形式中,刚度偏心影响弹性抗震需求,而强度偏心对弹塑性抗震需求的影响最大。建议在结构弹塑性分析中宜增加强度偏心作为平面不规则结构的判定标准。同一地震工况下控制不同反应指标的最佳强度中心-刚度中心相对位置有所不同,综合考虑后的较优区间是强度中心介于质心和刚心之间。(3)研究速度脉冲强震作用下多高层偏心RC框架结构的弹塑性抗震需求和地震易损性。探讨不同偏心形式对多层框架弹塑性抗震需求的影响程度;以基于N-M模型的一般化多层偏心RC框架模型为对象,研究其弹塑性抗震需求变化规律。建立偏心结构的地震易损性分析方法,对多高层强度偏心RC框架结构进行2.4万次动力时程分析,建立其最大层间单元位移、延性和扭转角的地震易损性曲线。结果表明,一般化多层偏心体系中,底层偏心对弹塑性抗震需求的影响大于其他层偏心,各层均匀偏心工况最为不利。多高层强度偏心框架结构在速度脉冲地震作用下相对于非速度脉冲地震作用下有更大的地震需求超越概率。随着偏心率的增大,最大层间单元位移角、延性和层间扭转角的超越概率均增大,且偏心率对延性超越概率的影响最为明显。(4)建立偏心RC框架结构延性折减系数的修正方法和修正系数拟合式。基于反应谱理论,提出对称结构延性折减系数Rμ应用于偏心结构时的修正方法,探讨偏心率、楼层数、延性水平和速度脉冲地震效应对修正系数的影响规律。通过多元非线性回归分析,建立修正系数和各影响因素之间的拟合关系式,并给出应用示例。结果表明,修正系数的主要影响因素是偏心率、结构延性水平和速度脉冲地震效应,楼层数的影响不明显。建立的修正系数拟合式能综合考虑结构偏心和速度脉冲地震效应的影响,更为全面和合理地表征Rμ-μ-T关系。(5)建立偏心RC框架结构基于强度折减系数的抗震设计方法。在评估目前的有害层间位移计算方法基础上,提出层间平均剪切变形角和层间平均转角的概念,并进行关系推导和有效性验证。评估强度折减系数R在当今国际主要抗震设计规范中的应用情况,建立偏心RC框架结构基于强度折减系数的抗震设计方法并给出设计实例。该方法以R-μ-T关系为基础,以控制有害位移为参考手段,以评估可接受失效概率为指导,在借鉴已有成果基础上进一步考虑了偏心率、竖向不规则、速度脉冲效应对R的综合影响,使得强度折减系数的考虑更为全面。
[Abstract]:Eccentric layout and near-fault velocity pulse seismic action are two extremely disadvantageous conditions in structural seismic design. In this paper, the seismic requirements and design methods of eccentric reinforced concrete (RC) frame structures subjected to velocity pulse earthquake are studied by combining the two conditions considered separately in the past. The purpose of this paper is to develop a restoring force model considering axial force-moment interaction, quantitatively study the seismic demand of eccentric RC frame structures under strong earthquake with velocity pulse, and propose a correction method of ductility reduction coefficient, so as to establish the seismic design method of eccentric structures based on strength reduction coefficient. The main research works are as follows: (1) Develop the axial force-moment interaction model (N-M model). Develop the restoring force model considering axial force-moment interaction based on VC++ platform and metal plasticity principle. Evaluate the validity and calculation of N-M model by analyzing RC frame structure model with actual earthquake damage records and a super high-rise building structure. The results show that N-M model can obtain more reliable results in structural elastoplastic analysis, and the calculation efficiency is much higher than that of fiber model or multi-spring model. The aseismic demand of single-story eccentric RC shear wall and frame structure subjected to impulsive earthquake is studied. The mechanism of the influence of different eccentric forms and axial forces on the aseismic demand of the structure is revealed, and the relative positions of the optimum strength center and stiffness center are discussed. The results show that the single-story eccentric RC shear wall and frame structure have greater elastic and elastic-plastic seismic requirements under the action of velocity pulse than under the action of non-velocity pulse. Stiffness eccentricity has the greatest influence on elastic-plastic seismic demand. It is suggested that the strength eccentricity should be added to the elastoplastic analysis as the criterion for judging the plane irregular structure. The relative position of the optimum strength-stiffness center of the response index is different, and the optimum strength center is between the center of mass and the center of rigidity. (3) The elastic-plastic seismic demand and seismic vulnerability of multi-story and high-rise eccentric RC frame structures subjected to strong velocity pulse earthquake are studied. Based on the N-M model, the elastic-plastic seismic demand of multi-storey eccentric RC frame is studied. The seismic vulnerability analysis method of eccentric structure is established. The dynamic time history analysis of multi-storey and high-rise eccentric RC frame structure is carried out 24,000 times, and the maximum inter-storey element displacement and delay are established. The results show that in the general multi-story eccentric system, the influence of the bottom eccentricity on the elastic-plastic seismic demand is greater than that of the other layers, and the uniform eccentricity of each layer is the worst. The multi-story eccentric frame structure under the action of velocity pulse earthquake is larger than that under the action of non-velocity pulse earthquake. With the increase of eccentricity, the exceeding probability of maximum displacement angle, ductility and torsion angle increases, and the influence of eccentricity on the exceeding probability of ductility is most obvious. (4) The correction method and fitting formula of ductility reduction coefficient of eccentric RC frame structure are established. The correction method of symmetrical structure ductility reduction coefficient R_ u applied to eccentric structure is presented. The influence of eccentricity, floor number, ductility level and velocity pulse seismic effect on correction coefficient is discussed. It is shown that the main factors affecting the correction factor are eccentricity, ductility level and velocity pulse seismic effect, and the influence of floor number is not obvious. On the basis of evaluating the present calculation methods of harmful interlayer displacement, the concepts of average interlayer shear deformation angle and average interlayer rotation angle are put forward, and the relationship between them is deduced and validated. The application of strength reduction coefficient R in the main international seismic design codes is evaluated, and eccentric RC is established. The seismic design method of frame structure based on strength reduction coefficient is presented and an example is given. The method is based on R-u-T relation, takes harmful displacement control as a reference method, takes acceptable failure probability as a guide, and takes eccentricity, vertical irregularity and velocity pulse effect into account. The strength reduction factor is considered more comprehensively.
【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TU375.4;TU352.11

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