箍筋约束混凝土方柱轴压破坏尺寸效应细观数值研究

Mesoscopic simulation of size effect on stirrup-confined concrete columns under axial compression

钢筋混凝土构件尺寸效应行为源于混凝土材料的非均质性及钢筋/混凝土复杂的非线性相互作用.通过建立反映上述特征的约束混凝土方柱3D细观数值模型,开展轴心受压破坏行为及尺寸效应数值研究,探讨体积配箍率对箍筋约束混凝土方柱轴心受压力学行为及尺寸效应的影响机理,并与试验结果进行对比分析.基于Baznt尺寸效应律,开展约束混凝土轴心抗压强度尺寸效应理论分析.研究结果表明:数值模拟与试验结果吻合良好,构建的钢筋混凝土柱细观力学模型能够准确地描述箍筋约束混凝土构件的破坏行为及尺寸效应规律;体积配箍率增加,约束混凝土柱的名义强度增大、破坏呈现更少的脆性,尺寸效应现象减弱;Baznt尺寸效应理论能够对约束混凝土柱轴心加载下的尺寸效应行为做出合理解释.

Size effect of reinforced concrete （RC） members is mainly caused by the heterogeneity and mutual effect of concrete and steel.Considering of the above influential factors,the 3D meso-mechanical models of stirrup-confined concrete square columns were set up and the damage process subjected to axial compressive loading was simulated. The confinement effect on the failure patterns and the axial compressive strength of the stirrup-confined columns was explored. Moreover,the simulated results were compared with test data. Based on the basic theory of the size effect law （SEL） proposed by Baznt,size effect of stirrup-confined concrete columns was analyzed. It was showed that the simulated results have a good consistence with the test data and the mesoscopic analysis models of RC columns can accurately describe the damage behavior and size effect of stirrup-confined columns. With the increase of stirrup ratio,the nominal strength and deformation behavior of columns boost. Then,it becomes little brittle in the damage process. Therefor the size effect is little obvious. The simulation data fit well with basic theory of the size effect law（SEL） proposed by Baznt.