高强钢组合K形偏心支撑结构的结构影响系数和位移放大系数研究

A Study on the Structural Influence Coefficient and Displacement Amplification Coefficient of High-Strength Steel Composite K-type Eccentrically Braced Structure

高强钢组合K形偏心支撑结构是指耗能梁段采用普通钢材(如Q345钢),而框架梁、柱采用高强度钢材(如Q460钢)的结构。耗能梁段在大震作用下剪切屈服耗散能量,而梁柱构件基本处于弹性受力状态,保证地震作用下的塑性变形仅集中于耗能梁段。结构影响系数R是基于性能的抗震设计方法中至关重要的部分,R取值合理是结构抗震性能设计的关键。我国2016版《建筑抗震设计规范》(GB 50011—2010)中隐藏了结构影响系数的概念,且对所有的结构体系取统一值,显然不尽合理。通过基于性能的抗震设计方法分别设计了结构层数(5层、10层、15层、20层)与耗能梁段长度(900 mm、1000 mm、1100 mm、1200 mm)各不相同的高强钢组合K形偏心支撑结构,分别采用静力非线性推覆分析法(Pushover分析法)和增量动力分析方法(IDA方法)模拟出不同结构模型的底部剪力-顶点位移曲线,将性能曲线转化为可与设防地震需求谱和罕遇地震需求谱相交的能力谱曲线,进而计算出结构影响系数R和位移放大系数Cd,分析结构层数与耗能梁段长度对性能系数的影响。最后,对比所有模型结构使用两种计算方法所得的性能系数值,提出各性能系数的建议取值,为高强钢组合K形偏心支撑结构的抗震设计提供建议。

The high-strength steel composite K-type eccentrically braced structure is a new structure type.The ordinary steel(f;≤345 MPa)is utilized in the links to ensure the structure has good plastic deformation ability under strong earthquake,and high-strength steel(f;≥460 MPa)is used in the frame beam and column to reduce the cross-section while ensuring the elastic stress state of the non-energy consuming components.The structural influence coefficient R is a crucial part of the performance-based seismic design method.The seismic design of structure is more reasonable and economical if a reasonable value of R is used.It is not reasonable to ignore the concept of the structural influence coefficient and adopt a constant value for all structural systems in the Code for Seismic Design of Buildings(GB50011—2010),2016 edition.A series of K-type eccentrically braced steel frames with high-strength steel combination with different story(5 story,10 story,15 story,20 story)and the length of links(900 mm,1000 mm,1100 mm,1200 mm)are designed based on performance-based seismic design method.The static nonlinear pushover analysis method and incremental dynamic analysis method(IDA method)are carried out.The performance curves are obtained by Pushover and IDA method.The R and Cd,of each prototype structure are calculated by the capability spectrum method,and the influence of the number of structural story and the length of link on the performance coefficient are analyzed.Finally,comparing the results of Pushover analysis method and IDA method,the proposed values of each performance coefficient are proposed to provide a reference for the performance design of this new structural system in the future.