结构尺寸对钢筋混凝土短柱抗震性能影响:细观分析

EFFECT OF STRUCTURAL SIZE ON SEISMIC PERFORMANCE OF REINFORCED CONCRETE SHORT COLUMNS——A MESO-SCALE STUDY

地震作用下,钢筋混凝土短柱由于承受竖向和水平荷载共同作用而往往产生脆性压-剪破坏行为,该脆性破坏可能表现出尺寸效应行为。借助混凝土细观结构特征,考虑非均质性以及钢筋/混凝土非线性相互作用的影响,建立了钢筋混凝土短柱力学行为研究的三维细观尺度数值模型。在模拟结果与试验结果吻合良好的基础上,研究了轴压比对不同结构尺寸尤其是大尺寸钢筋混凝土短柱抗震性能,如抗剪承载力、滞回特性、延性性能和耗能能力等参数的影响。最后,借助相关试验和模拟数据,基于经典的Ba?ant尺寸效应律思想提出了能够反映尺寸效应影响钢筋混凝土短柱抗剪承载力修正公式。

Under the action of earthquake, reinforced concrete （RC） short columns often undergo brittle compression-shear failure due to the combined effects of vertical and horizontal loadings. The brittle failure may exhibit obvious size effect of the columns. Considering the meso-scale structural characteristics of concrete, the heterogeneity of concrete and the nonlinear interaction between steel bars and surrounding concrete, a three-dimensional meso-scale numerical model is established to study the mechanical behavior and seismic performance of reinforced concrete short columns with different structural sizes. The meso-scale simulation results are in good agreement with the available experimental results. Moreover, the effect of the axial compression on the seismic performance of RC short columns with different sizes, especially large-sized ones is investigated, including the shear bearing capacity, hysteretic behavior, ductility and energy dissipation capacities. Finally, based on the classical Size Effect Law （SEL） proposed by Ba？ant, a modified formula is proposed to reflect the size effect on the shear capacity of reinforced concrete short columns.