钢筋混凝土柱轴压强度尺寸效应影响因素分析

Analyses of the Influencing Factors on the Size Effect of Axial Compressive Strength of RC Columns

钢筋混凝土构件的尺寸效应主要是由混凝土材料本身的非均质性和力学性能的非线性和钢筋/混凝土相互作用的高度复杂性共同导致的.影响钢筋混凝土柱轴压破坏及名义强度尺寸效应的因素主要包括：长细比、纵筋配筋率、配箍率及混凝土强度等级等.本文设计了最大截面尺寸为600mm×600mm的18组几何相似的钢筋混凝土柱,对其在轴心压缩加载作用下的破坏行为进行了试验研究,并对钢筋混凝土柱名义轴压强度尺寸效应的影响因素进行了分析与讨论.研究表明：（1）Ba6ant提出的＂尺寸效应律＂能够较好地描述大尺寸钢筋混凝土柱名义轴压强度的尺寸效应规律;（2）随长细比增加,纵筋配筋率/配箍率减小,混凝土强度等级提高,钢筋混凝土柱名义轴压强度尺寸效应越明显.

The size effect of reinforced concrete（ RC） members is mainly caused by： 1） the heterogeneity and the mechanical nonlinearity of concrete; and 2） the complex mutual effect between steel rebar and the surrounding concrete. The influencing factors on the size effect of RC members（ e. g. RC columns） include slenderness ratio,reinforcement ratio and the grade of concrete strength,etc. A total of 18 geometrically similar RC columns,the maximum crosssectional size of which was 600 mm × 600 mm,were conducted. The failure behavior of the RC columns subjected to axial compressive loading was studied and the influencing factors on the size effect of nominal axial compressive strength were analyzed and discussed. The investigation indicates that,1） the bi-logarithmic plots of nominal axial compressive strengths for large-scale RC columns follows closely the ＂size effect law（ SEL） ＂proposed by Bazant; 2） the size effect of nominal axial compressive strength becomes more pronounced with the increase of slenderness ratio,the decrease of reinforcement ratio and the increase of the grade of concrete strength.