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为确定防屈曲支撑在结构中的布置方式以使结构抗震性能充分发挥,提出了基于能量平衡的防屈曲支撑-钢筋混凝土框架结构抗震塑性设计方法。构建了结构的“强柱弱梁”整体屈服机制,采用侧力比将总结构体系离散为防屈曲支撑体系和纯框架体系,并建立了结构的双线性能力曲线。基于能量平衡方法计算结构的设计基底剪力并分别得到支撑体系和框架体系的设计侧向力,进而完成支撑的截面设计。按照塑性内力分配机制和考虑支撑屈服后性能,计算梁柱构件内力需求。以一幢5层结构为例,分别设计了不同侧力比的14个结构模型,对比了基底剪力、防屈曲支撑面积和梁柱钢筋用量等。通过22条地震波下的弹塑性时程分析,研究了不同侧力比结构的最大层间位移角、屈服机制、楼层剪力比、支撑最大位移延性、累积位移延性和结构残余层间位移角。分析结果表明:所提出的方法能实现结构的预期失效模式,并满足结构的抗震性能要求,并建议设计侧力比选取在0.3~0.5之间。
In order to determine the arrangement of anti-buckling brace in the structure so that the seismic performance of the structure can be brought into full play, a buckling-resistant design method based on energy balance is proposed for the seismic plasticity design of reinforced concrete frame structure. The structure of the “strong column weak beam ” the overall yield mechanism, using the lateral force ratio of the total structural system discrete buckling support system and pure frame system, and the structure of the bilinear capacity curve. Based on the energy balance method, the design base shear of the structure is calculated and the designed lateral force of the support system and the frame system are obtained respectively, and the cross-section design of the support is completed. According to the plastic internal force distribution mechanism and considering the post-yielding performance, the internal force needs to be calculated. Taking a 5-story structure as an example, 14 structural models with different lateral force ratios were designed respectively to compare the base shear force, the buckling support area and the amount of steel bar and beam reinforcement. Based on the elasto-plastic time-history analysis of 22 seismic waves, the maximum inter-story drift angle, yield mechanism, floor shear ratio, maximum displacement ductility, cumulative displacement ductility and residual displacement between structural layers of different lateral ratio structures are studied. The analysis results show that the proposed method can achieve the expected failure mode of the structure and meet the seismic performance requirements of the structure. It is suggested that the design lateral force ratio should be between 0.3 and 0.5.