不等肢混凝土异形柱轴压比与配箍特征值关系研究

在《混凝土异形柱结构技术规程》(JGJ149-2006)中,采用了对异形柱在不同抗震等级下取不同的曲率延性比的方法来确定轴压比与配箍特征值的关系,编制依据来源于对12960种工况下等肢柱和部分不等肢L形柱延性的分析。基于相同的本构模型及极限曲率判别标准,该文对1456种工况下的不等肢T形柱、十形柱截面延性进行了非线性数值分析,从中拟合出它们在不同延性比下的轴压比与配箍特征值的关系曲线,并与等肢异形柱在相同的延性比下进行了比较,得出以下结论:1)不等肢T形柱轴压比-配箍特征值曲线在等肢T形柱曲线上下微小波动,基本一致;2)不等肢十形柱,当不等肢系数(长肢肢高/短肢肢高)小于1.4时,轴压比-配箍特征值曲线与等肢十形柱基本一致;但当系数较大时,轴压比最大下降了0.07―0.08,建议对此类柱采取在肢端增设暗柱,或在相同配箍率的条件缩小箍筋间距的方法来提高轴压比。

STUDY ON AXIAL COMPRESSION RATIOS AND STIRRUP CHARACTERISTIC VALUES OF RC INEQUIAXIAL SPECIALLY SHAPED COLUMNS

In national technical specification with specially shaped columns(JGJ149-2006),the relationship between axial compression ratio and stirrup characteristic value in various seismic grades were derived according to various ductility level,which came from ductility analysis of 12960 equiaxial specially shaped columns and some inequiaxial L-shaped columns.Based on the same constitutive model and the ultimate curvature criteria,the ductility of 1456 inequiaxial T-shaped and cross-shaped columns are analyzed by nonlinear method,and the curves between axial compression ratio and stirrup characteristic value in various ductility level are derived. Comparing with equiaxial columns in the same ductility ratio,some conclusions are derived:1)the inequiaxial T-shaped column curves between axial compression ratio and stirrup characteristic value are similar to theequiaxial columns;2)the inequiaxial cross-shaped column curves between axial compression ratio and stirrup characteristic value are similar to the equiaxial columns when the ratios of the flange length are less than 1.4,but the axial compression ratio may reduce 0.07―0.08 when the ratios are great.It is suggested to add concealed columns or shortening stirrup space in the same stirrup reinforcement ratio to increase axial compression ratio in the latter.