考虑柱偏心距随机特性的RC框架“强柱弱梁”设计可靠度  

Reliability of ‘strong column and weak beam’ design for RC frames considering random eccentricity of columns

作　　者：蒋友宝 周浩 曹青 孙国衡 JIANG Youbao;ZHAO Hao;CAO Qing;SUN Guoheng(School of Civil Engineering,Changsha University of Science and Technology,Changsha 410114,China)

机构地区：[1]长沙理工大学土木工程学院

出　　处：《建筑结构学报》2019年第9期187-195,共9页Journal of Building Structures

基　　金：国家自然科学基金项目(51678072);长沙理工大学土木工程重点学科创新性项目(18ZDXK01)

摘　　要：针对地震作用下钢筋混凝土(RC)框架结构大多出现“强梁弱柱”破坏机制的问题,考虑混凝土极限压应变、抗压强度和钢筋屈服强度等参数的变异性以及柱截面受拉的可能性,基于静力平衡方程求解得到了梁柱抗力的精细分析模型。结合已有的水平地震作用、竖向重力荷载、混凝土和钢筋本构参数等的概率模型,并考虑柱截面偏心距的随机特性,采用Monte Carlo方法分析了不同设计参数下RC框架“强柱弱梁”设计可靠度。结果表明:按GB 50011—2010中柱端弯矩增大系数进行设计时,考虑超配钢筋后,其“强柱弱梁”可靠度均有较大程度下降;当按梁端实配钢筋设计时,考虑随机偏心距、轴压比等参数的影响,其“强柱弱梁”可靠度在2.44~4.14范围内波动;与考虑随机偏心距情形相比,按固定偏心距计算会高估“强柱弱梁”可靠度;对于四级抗震框架结构,当梁端顶部和底部钢筋分别超配30%与20%时,其“强柱弱梁”可靠度约为考虑随机偏心距情形的5倍。In earthquakes,reinforced concrete(RC)frames mostly fail by the‘strong beam-weak column’mechanism.To address this problem,refined resistance models of beams and columns were obtained with static equilibrium equations,considering variations of parameters(e.g.ultimate strain of concrete,strengths of concrete and steeletc.)and the possibility of columns in tension.Based on the existing probability models of horizontal earthquake action,vertical gravity load and key parameters in the constitutive relations of concrete and steel reinforcement,the reliability of the‘strong column-weak beam’design was calculated by the Monte Carlo method for RC frames with different design parameters,considering the random properties of eccentricity for column sections.The results show that:when designing according to the moment amplification factors at the end of column prescribed in GB 50011—2010,the reliability of the‘strong column-weak beam’design decreases greatly after taking the over reinforcement into account;when the actual reinforcement of beam end is adopted for design,as well as the influence of random eccentricity,the axial compression ratio and other parameters are considered,the reliability of‘strong column-weak beam’design still fluctuates in the range of 2.44 to 4.14.Compared with the case of random eccentricity,the fixed eccentricity method overestimates the reliability of‘strong column-weak beam’design.For frame structures of anti-seismic grade four,when the top and bottom of beam ends are over reinforced by 30%and 20%respectively,the reliability of the‘strong column-weak beam’design is about five times than that of the corresponding random eccentricity case.

关 键 词：强柱弱梁 设计可靠度 RC框架 偏心距 水平地震作用 柱截面 钢筋屈服 重力荷载 

分 类 号：TU375.4[建筑科学—结构工程] TU318.1