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通过5根无箍筋和7根有箍筋矩形截面钢筋混凝土框架柱试验,研究不同加载角度时,低周往复斜向水平荷载作用下,矩形截面框架柱双向受剪的破坏机理和计算方法。结果表明,不能用单向剪切理论计算矩形截面框架柱双向受剪承载力的原因,主要是矩形截面框架柱双向受剪时,斜裂缝开展迅速,部分混凝土提前退出工作,导致轴压力对混凝土强度的提高作用有限。其次,按单向剪切理论计算矩形截面框架柱双向受剪承载力时,两个方向共用一个混凝土截面,重复考虑了混凝土的抗剪能力。据此分析无腹筋矩形截面框架柱双向受剪承载力的相关性,并用椭圆方程描述其相关关系,提出对混凝土项和轴力项共同折减的双向剪切理论,并建立低周往复水平荷载作用下矩形截面框架柱双向受剪承载力的计算公式。计算结果与试验值相比表明是偏于安全的。最后考虑承载力抗震调整系数,给出了考虑地震作用时矩形截面框架柱双向受剪承载力的建议公式。
The failure mechanism and calculation method of biaxial shearing of rectangular cross-section frame columns under different horizontal and vertical cyclic loadings under different loading angles were studied by five unconfined bars and seven reinforced concrete columns with stirrup rectangular columns. The results show that the reason that the uniaxial shearing theory can not calculate the bidirectional shear strength of rectangular cross-section frame columns is that the diagonal cracks develop rapidly when the frame columns with rectangular cross-section are biaxially sheared and part of the concrete is withdrawn ahead of schedule, Strength improvement is limited. Secondly, when one-way shearing theory is used to calculate the bi-directional shear bearing capacity of rectangular cross-section frame columns, a concrete section is shared by both directions, and the shear capacity of concrete is considered repeatedly. Based on this, the correlation between the two-way shear capacity of frame columns without web reinforcement and rectangular section was analyzed. The elliptic equation was used to describe the relationship between them. The two-way shear theory was proposed to reduce the total of concrete and axial force, The Calculation Formula of Biaxial Shear Bearing Capacity of Rectangular Cross Section Frame Columns Under. The calculated results show that it is biased in comparison with the experimental values. Finally, considering the earthquake resistance adjustment factor of bearing capacity, the formula of bidirectional shear strength of rectangular frame columns considering earthquake action is given.