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旨在揭示箍筋约束作用对高强钢筋混凝土(RC)柱在小偏心(e_0=0.25h_0)受压加载下尺寸效应行为的影响.开展了最大横截面尺寸为800 mm×800 mm的12组几何相似的配箍率为0和0.66%的高强混凝土柱试验,此外,建立了钢筋混凝土柱力学行为分析的细观尺度分析模型,并在模拟与试验结果吻合良好的基础上,补充开展了更大配箍率柱(即:1.2%和2.4%)的数值试验,进而对偏心受压加载下柱的力学行为,包括破坏模式、名义受压应力,应变关系、承载力、名义压缩强度及峰值后软化行为等进行了研究,并对其名义压缩强度的尺寸效应进行了分析,进而揭示箍筋约束作用对小偏心加载高强钢筋混凝土柱破坏行为及尺寸效应影响机制,结果表明:1)小偏心受压加载下高强钢筋混凝土柱名义压缩强度存在明显的尺寸效应;2)Bazant尺寸效应律能够较好地描述钢筋混凝土柱在偏心受压加载下的尺寸效应行为;3)箍筋约束作用能够明显提高钢筋混凝土柱的强度及延性,且会削弱其尺寸效应;4)本文建立的细观数值模型能够很好地表征钢筋混凝土柱力学性能.
The aim of this study was to reveal the effect of stirrups on the size effect of high-strength reinforced concrete (RC) columns subjected to small eccentric loads (e0 = 0.25h_0). Twelve groups of geometries with maximum cross-section of 800 mm × 800 mm Similar to the high-strength concrete columns with a stirrup rate of 0 and 0.66%, a meso-scale analysis model for the mechanical behavior analysis of reinforced concrete columns was built. Based on the good agreement between the simulation results and the experimental results, The mechanical behavior of the column under eccentric compression loading, including failure mode, nominal compressive stress, strain relation, bearing capacity, nominal compressive strength and peak value, was numerically tested with the stirrup rate columns (ie, 1.2% and 2.4% Softening behavior were studied and the size effect of the nominal compressive strength was analyzed. Then the mechanism of the confinement effect of stirrup on the failure behavior and size effect of the small eccentricity loaded high-strength reinforced concrete column was revealed. The results showed that: 1) The compressive strength of high strength reinforced concrete columns under compressive loading has obvious size effect; 2) The size effect law of Bazant can describe the size effect of reinforced concrete columns under eccentric compression loading The behavior of stirrups should be able to improve the strength and ductility of RC columns obviously and weaken the size effect. (4) The mesoscopic numerical model established in this paper can well characterize the mechanical properties of RC columns.