MESO-SCALE ANALYSIS OF SIZE EFFECT ON ASEISMIC BEHAVIOR OF REINFORCED CONCRETE SQUARE COLUMNS STRENGTHENED WITH CFRP
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摘要: 为研究CFRP加固钢筋混凝土方柱在地震作用下的破坏模式，该文考虑混凝土材料的非均质性、钢筋-混凝土间的粘结滑移作用，建立了CFRP加固钢筋混凝土方柱三维细观数值模型。在验证数值模型与试验结果吻合良好的基础上，扩展工况探讨了轴压比、CFRP体积配置率对CFRP加固钢筋混凝土方柱抗震性能及名义抗剪强度尺寸效应的影响。结果表明：一定轴压比范围内柱的承载力随轴压比增大而提高，但其延性会降低；该文工况中，CFRP加固钢筋混凝土柱的名义抗剪强度随试件尺寸增大呈降低趋势，存在着明显尺寸效应行为；在经典材料层次尺寸效应律基础上，提出了CFRP加固混凝土方柱名义抗剪强度尺寸效应理论公式(适用范围轴压比小于0.4)，模拟结果证实了公式的合理性。
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关键词:
- CFRP加固混凝土方柱 /
- 抗震性能 /
- 轴压比 /
- 体积配置率 /
- 尺寸效应
Abstract: In order to study the failure mechanism of RC columns strengthened by CFRP subjected to axial and cyclic lateral loads, a three-dimensional meso numerical model of reinforced concrete square columns strengthened with CFRP is established, considering the heterogeneity of concrete materials and the bond slip between reinforcement and concrete. On the grounds of the good agreement between the meso-scale simulation results with the available experimental results, the section size of the specimens is enlarged. Furthermore, the effects of axial compression ratio, volume allocation rate of CFRP on the aseismic performance and size effect on shear strength of reinforced concrete short columns strengthened with CFRP are explored. The results show that: the bearing capacity of specimens increases as the increase of axial compression ratio, but the ductility decreases; increasing the volume allocation ratio of CFRP has a limited effect on the increase of bearing capacity, which will enhance the ductility of columns; with the increase of specimen size, the nominal shear strength of columns tends to decrease, and there exists size effect behavior. -
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图 1 CFRP加固钢筋混凝土柱3D细观数值模型
Figure 1. 3D meso-numerical model of reinforced concrete columns confined by CFRP
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图 4 钢筋混凝土柱模拟结果与试验结果对比
Figure 4. Comparison of simulated and experimental results of square RC columns
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图 5 CFRP加固钢筋混凝土柱试验与模拟破坏形态对比
Figure 5. Comparisons between experimental and simulated failure modes of square RC columns strengthened with CFRP
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图 6 CFRP加固钢筋混凝土方柱骨架曲线对比
Figure 6. Comparison of skeleton curves of square RC columns strengthened with CFRP
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图 7 不同尺寸CFRP加固钢筋混凝土方柱的滞回曲线
Figure 7. Hysteretic curves of square RC columns strengthened with CFRP of different sizes
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图 8 不同尺寸CFRP加固钢筋混凝土方柱的骨架曲线
Figure 8. Skeleton curves of square RC columns strengthened with CFRP of different sizes
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图 9 位移延性系数与截面宽度的关系
Figure 9. The relationship between displacement ductility coefficient and section size
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图 10 轴压比对柱子名义抗剪强度的影响
Figure 10. Influence of axial compression ratio on nominal strength of columns
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图 11 未加固混凝土柱名义抗剪强度尺寸效应拟合情况
Figure 11. Size effect fitting of nominal shear strength of plain concrete columns
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图 13 CFRP约束混凝土柱名义抗剪强度尺寸效应拟合(n=0.4)
Figure 13. Size effect fitting of nominal shear strength of CFRP-confined concrete columns (n=0.4)
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图 14 模拟结果与现有理论抗剪强度计算值的对比
Figure 14. Comparison of simulation results with theoretical results about shear strength
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图 15 模拟结果与理论计算值的对比情况
Figure 15. Comparison between simulation results and theoretical calculation values
表 1 粘结-滑移本构参数
Table 1 Parameters utilized in the bond-slip model
关键点 开裂 峰值 残余 应力 τ/MPa τcr=2.5ft τu=3ft τr=ft 滑移 s/mm scr,l=0.025d su,l=0.04d sr,l=0.55d 
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表 2 混凝土细观组分及钢筋力学参数
Table 2 Mechanical parameters of the three meso components of concrete and reinforcing bars utilized
组分 粗骨料 砂浆基质 界面过渡区 纵筋 箍筋 抗压强度σc/MPa − *53.1 ^48.2 − − 抗拉强度σt/MPa − *5.2 ^4.7 − − 弹性模量E/GPa *60 *42.5 ^38.4 *210 *200 泊松比ν *0.2 *0.2 ^0.2 *0.3 *0.3 屈服强度fy/MPa − − − *380.71 *419.09 配筋率ρ/(%) − − − *1 *0.5 注：*为试验实测值[9]；^为反复试算取值。
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表 3 CFRP加固钢筋混凝土柱几何参数
Table 3 Geometrical parameters of the RC columns strengthened with CFRP
试件名称 截面宽度B/mm 柱高H/mm 轴压比n 体积配置率 ρf /(%) SC-200-0.4-1 200 600 0.4 0.000 SC-200-0.4-2 200 600 0.4 0.334 SC-200-0.4-3 200 600 0.4 1.336 SC-200-0.6-1 200 600 0.6 0.000 SC-200-0.6-2 200 600 0.6 0.334 SC-200-0.6-3 200 600 0.6 1.336 SC-400-0.4-1 400 1200 0.4 0.000 SC-400-0.4-2 400 1200 0.4 0.334 SC-400-0.4-3 400 1200 0.4 1.336 SC-400-0.6-1 400 1200 0.6 0.000 SC-400-0.6-2 400 1200 0.6 0.334 SC-400-0.6-3 400 1200 0.6 1.336 SC-800-0.4-1 800 2400 0.4 0.000 SC-800-0.4-2 800 2400 0.4 0.334 SC-800-0.4-3 800 2400 0.4 1.336 SC-800-0.6-1 800 2400 0.4 0.000 SC-800-0.6-2 800 2400 0.4 0.334 SC-800-0.6-3 800 2400 0.4 1.336
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