基于能力谱的弯剪复合型金属阻尼器加固既有混凝土框架性能化抗震设计方法

SEISMIC DESIGN OF CONCRETE FRAMES UPGRADED BY SHEAR-BENDING COMBINED METALLIC DAMPERS BASED ON CAPACITY CURVE METHOD

  • 摘要: 随着近年来中国对建筑结构的抗震性能要求不断提高,既有混凝土框架难以满足多水准抗震性能标准的要求,采用金属阻尼器加固既有混凝土框架可显著提高其抗震性能,有利于满足现有抗震性能目标,然而目前对于相应的的性能化抗震设计方法研究尚不充分。该文提出了基于能力谱的金属阻尼器加固既有混凝土框架抗震性能化设计方法,为了实现不同烈度地震下的多性能水准目标,采用具有多阶屈服特征的弯剪复合型金属阻尼器。基于对既有混凝土框架的静力推覆分析,将框架的推覆曲线转化为等效的双折线能力谱,设定加固后结构在多遇、设防和罕遇地震下的层间位移角性能目标,确定结构能力谱曲线和需求谱曲线的交点。考虑金属阻尼器进入屈服阶段后的附加阻尼比,计算出结构在不同烈度地震下的等效阻尼比,根据性能点计算出金属阻尼器剪切和弯曲芯板的屈服承载力。基于上述设计方法对4层、6层和9层既有混凝土框架进行加固,通过OpenSees软件建立弹塑性分析模型,并通过试验结果验证了模型的准确性,通过时程分析结果表明了加固后的结构满足预定的性能目标,证明了提出的设计方法的可靠性和有效性。该文研究成果将为金属阻尼器加固既有混凝土框架的抗震设计提供理论依据。

     

    Abstract: With the increasing seismic performance requirements of structures in recent years, existing concrete frames could not meet the requirements of multi seismic performance objectives. Adding metallic damper in existing concrete frames could significantly improve their seismic performance to meet current performance objectives. However, there is still lack of seismic design method for concrete frames upgraded by metallic damper. This paper proposed a seismic design method for concrete frames upgraded by metallic damper based on the capacity curve method, in which the shear-bending combined damper with multi-stage yielding feature was incorporated to achieve various performance objectives under different earthquake intensities. The equivalent bilinear capacity of concrete frames was obtained based on pushover results. The intersection points between the capacity curve of upgraded structure and demand spectrum could be determined after setting story drift performance objectives under frequently occurred, design-based and maximum considered earthquakes. The equivalent damping of the whole structure was calculated considering the additional viscous damping after the yielding of metallic damper. The yielding strength of shear and bending plates of metallic damper could be calculated through the performance intersection points. Following the design process, shear-bending combined dampers were designed to upgrade the 4-story, 6-story and 9-story concrete frames. The analytical modelling of the structures was established using OpenSees software and verified against the experimental results. It showed that the upgraded structures could meet the desired performance objectives through time-history analyses, indicating the efficiency and reliability of the design method. The research results in this paper provided guidelines on seismic design of metallic damper to upgrade concrete frames.

     

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