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钢筋混凝土柱名义轴压强度的尺寸效应源于:1)混凝土材料本身的非均质性及其力学非线性;2)钢筋/混凝土相互作用的高度复杂性.此外,长细比效应是影响钢筋混凝土柱最终破坏模式及其承载能力的另一重要因素.考虑混凝土材料细观结构的非均质性,及钢筋与混凝土间的非线性黏结滑移等因素,建立了钢筋混凝土柱轴心受压加载下力学行为研究的细观尺度力学分析模型.首先通过反演法确定了混凝土各细观组分的力学参数;进而对不同长细比钢筋混凝土柱在轴心受压加载下的破坏行为进行了数值模拟研究.结果表明:低长细比柱轴压加载下主要发生压剪破坏;而高长细比柱则发生屈曲失稳破坏,且由于端部效应的影响,破坏区域集中于柱的端部;长细比值小于9时,柱名义强度无明显变化,而大于9时,柱的屈曲强度迅速降低.
The size effect of the nominal axial compressive strength of RC columns comes from: 1) the heterogeneity of the concrete material and its mechanical nonlinearity; 2) the high complexity of the interaction between the rebar and the concrete. In addition, The ultimate failure mode of concrete column and its bearing capacity are another important factor.According to the heterogeneity of meso-structure of concrete material and the non-linear bond and slip between reinforced concrete and concrete, the axial compression of reinforced concrete column At the meso-scale mechanics analysis model, the mechanical behavior of the mesostructures of concrete is determined by the inversion method. Then the failure behaviors of different slenderness concrete columns subjected to axial compression are investigated The numerical simulation results show that the compression-shear failure occurs mainly under the axial compression of low slenderness column, but the buckling failure occurs in the high slenderness column. Due to the effect of the end effect, the damage area concentrates on the column The slenderness ratio is less than 9, the column nominal strength no significant change, while greater than 9, the column buckling strength rapidly decreased.