Seismic performance of 3 specimens under high axial compression ratio (0.25~0.55) and cyclic loading was studied firstly. Compared to the experimental results, reliability of shear capacity of the hollow column calculated by seismic codes and literatures was analyzed. Based on identification of column shear capacity and ductility available in literatures, 41 specimens failed in shear or flexure-shear was gathered. Finally, an improved model for RC hollow column was proposed, quantifying the effect of increasing ductility on shear contribution of truss mechanism by stirrups. The results indicate that RC hollow columns with sufficient stirrups would still fail in flexure-shear under high axial compression with obvious weak shear strength. Model in AASHTO code well predicts the shear bearing capacity of specimens, which is applicable to primary shear design of hollow columns with high axial load. Comparing the models in literatures, UCB and UCSD models that overestimate the capacity of all columns may be inappropriate to the shear evaluation of hollow column. Bi and Shin's model give a relatively accurate prediction for shear capacity of hollow columns, which may overestimate the shear capacity under the larger displacement. The improved Shin model proposed in this paper gives the best prediction and hence could be generally applicable to shear design of hollow columns at the bottom of building.%研究RC空心柱抗剪问题对发展建筑底部新型空心柱支撑体系具有重要意义.首先通过拟静力试验研究了3个矩形RC空心柱在高轴压比(0.25~0.55)下的抗震性能,随后比较了各国抗震设计规范及抗剪分析模型对高轴压作用下RC空心柱抗剪承载力计算的可靠性,最后对国内外41个发生剪切与弯剪破坏的矩形RC空心柱试件的抗剪强度与延性进行识别与统计,基于此并考虑延性对箍筋桁架机制抗剪的影响提出了改进抗剪承载力模型.结果表明:配置较多箍筋的RC空心柱在高轴压作用下仍会发生弯剪破坏,其侧向抗剪薄弱问题突出. AASHTO规范公式预测空心柱试件抗剪承载力较为准确,用于高轴压RC空心柱的初步抗剪设计是可行的.分析模型中UCB与UCSD模型普遍高估本文试件的抗剪能力,不适用于RC空心柱的抗剪评估.毕桂平模型、Shin模型对RC空心柱抗剪能力的预测较理想,但可能会高估其在较大位移延性下的抗剪承载力,而本文提出的改进Shin模型预测结果准确,可用于结构底部支撑体系中空心柱的抗剪设计.
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