RC框架柱端弯矩增大系数的可靠度评估  

Reliability assessment on column overdesign factor of RC frame

作　　者：任靖哲 张志刚 REN Jingzhe;ZHANG Zhigang(CITIC General Institute of Architectural Design and Research Co.,Ltd.,Wuhan 430014,China)

机构地区：[1]中信建筑设计研究总院有限公司,武汉430014

出　　处：《建筑结构》2023年第12期55-60,共6页Building Structure

摘　　要：由于弯矩增大系数选取不当,很多依据《混凝土结构设计规范》(GB 50010—2010)(2015年版)设计的框架结构在地震作用下无法实现预期中的梁铰机制。对《混凝土结构设计规范》(GB 50010—2010)(2015年版)中规定的柱端弯矩增大系数进行了基于可靠度方法的评估,评估方法包括三步:定义形成梁铰机制的极限状态,建立其地震易损性方程,计算出其形成梁铰机制的可靠度指标。初步建立了框架梁柱节点能否实现“强柱弱梁”机制的可靠度评价体系。采用弹塑性时程分析的方法计算了在不同梁端负弯矩调幅系数取值下的柱端弯矩增大系数所对应的可靠度指标,并将有限元分析结果与可靠度指标进行对比。研究结果表明,在不进行梁端负弯矩调幅和梁端负弯矩调幅系数取15%时,《混凝土结构设计规范》(GB 50010—2010)(2015年版)中规定的柱端弯矩增大系数的取值没有达到现行规范规定可靠度的要求;对于四级和三级框架结构,建议将柱端弯矩增大系数分别增大到1.35和1.4,并应在结构设计中较准确的计入楼板和填充墙对框架梁的增强作用。Many frame structures which are designed according to the requirements of Code for design of concrete structures(GB 50010—2010)(2015 edition),cannot achieve expected beam hinge mechanism due to the irrational value of column overdesign factor.The reliability of the column overdesign factor specified in the Code for design of concrete structures(GB 50010—2010)(2015 edition)was assessed.The framework was established by the three steps:define the limit state of beam hinge mechanism,build the seismic fragility function of beam-column joints,calculate the reliability index of beamcolumn joints achieve beam hinge mechanism.A preliminary reliability evaluation system has been established to determine whether the beam-column joint can achieve the"strong column weak beam"mechanism.With considering the different values of the coefficient of beam moment amplitude modulation,the reliability index of beam-column joints achieve beam hinge mechanism was derived from the results of time history analysis and the results were compared with the target reliability index.The results show that the reliability index of beam-column joints cannot meet the requirements that specified in Unified standard for reliability design of building structures(GB 50010—2010)(2015 edition),when the coefficient of beam moment amplitude modulation equals to 0%and 15%.The suggestions can be made:increase the value of column overdesign factor to 1.35 and 1.4 for the RC frame of 4th and 3rd seismic grade respectively.The enhancement of floor slab and filler wall on frame beams should be accurately included in the structural design.

关 键 词：框架结构 柱端弯矩增大系数 强柱弱梁 地震易损性方程 可靠度指标 

分 类 号：TU318.1[建筑科学—结构工程]