考虑尺寸影响的箍筋约束混凝土轴压本构模型

Compressive stress-strain model for stirrup-confined concrete columns considering the effect of structural size

已有箍筋约束混凝土轴压本构关系模型大多未考虑尺寸效应的影响,或通过采用强度折减系数法来粗糙反映尺寸的影响。为研究大尺寸箍筋约束混凝土柱轴心受压性能及尺寸效应规律,根据已有箍筋约束混凝土圆柱和方柱轴压破坏试验结果,分析了体积配箍率、箍筋形式(方箍及圆箍)及试件尺寸对箍筋约束混凝土应力-应变曲线的影响。考虑体积配箍率及箍筋形式的影响,建立了箍筋约束混凝土峰值应变尺寸效应公式,并结合前期箍筋约束混凝土名义轴压强度(峰值应力)尺寸效应公式,提出了可考虑尺寸影响的箍筋约束混凝土轴向压缩全应力-应变关系模型。与试验及模拟结果进行对比发现,建立的可考虑强度和峰值应变尺寸效应的本构关系与已有试验结果吻合较好,模型计算曲线与试验曲线接近。

Most of the existing constitute models of stirrup-confined concrete do not consider the size effect.A few consider the size effect using a strength reduction coefficient.In order to investigate the mechanical properties and size effect behaviors of the large-sized stirrup-confined RC columns under axial compressive load,the influence of volume stirrup ratio,the arrangement of stirrups as well as the specimen size on stress-strain curves of confined RC columns were analyzed based on the experimental results of the circular and squared concrete columns.The size effect formula of peak strain for stirrup-confined RC columns was established considering the influence of volumetric stirrup ratio and stirrup type.Moreover,combined with the size effect formula of peak stress in the previous study,the stress-strain model considering the size effect for stirrup-confined RC columns was proposed.Through comparison with the experimental and simulation data,it is demonstrated that the size effect formula of peak stress and peak strain showed good consistency with the experimental results,and the stress-strain model provided satisfactory predictions in large-sized stirrup-confined RC columns.