钢筋混凝土框架柱在轴压比超限时抗震性能的研究

首先讨论了钢筋、混凝土、配箍特征值和轴压比的平均值、标准值及设计值之间的关系,又推导出框架柱轴压比限值与截面界限相对受压区高度之间的计算公式。然后根据26个轴压比超限的框架柱在固定轴向荷载和水平反复荷载作用下的试验结果,主要分析了轴压比、配箍特征值、截面尺寸形状、混凝土强度等级、箍筋形式及剪跨比等因素对轴压比超限框架柱的骨架曲线、滞回曲线、位移延性及极限位移角的影响及作用。根据试验结果提出了钢筋混凝土框架柱轴压比超限值。最后根据近31根轴压比超限的钢筋混凝土框架柱试验结果,回归出试验柱延性系数和极限位移角与配箍特征值和轴压比之间的计算公式,根据回归公式确定出轴压比超限的抗震框架柱箍筋加密区最小配箍特征值的建议值,建议值与新规范值吻合的较好。

Seismic behavior of reinforced concrete frame columns with excessive axial compression ratios

Discussions are presented on the relationships between the average,standard and design values of reinforcing steel bars,concrete,and stirrup parameters and axial compression ratios.A calculation formula is derived for the relationship between the limiting axial compression ratio for frame columns and the relative compression region height in sectional limit disruptive.From the test results of 26 columns subjected to constant axial load and horizontal low-frequency cyclic load with excessive axial compression ratios,we have analyzed the effects of axial compression ratio,stirrup parameters,geometry of section,concrete strength grade,shear span-to-depth ratio,etc.,on the skeleton curves,hysteretic curves,ductility and limit drift ratios of the frame columns.Based on the test results,the limit values of axial compression ratio for reinforced concrete frame columns are proposed.Moreover,from the test results of 31 reinforced concrete frame columns,a regression formula is developed in terms of several parameters,namely,the ductility,limit drift ratio,axial compression ratio,and stirrup parameter.It was found that the proposed minimum stirrup parameters in the intensified stirrup region of seismic frame columns with excessive axial compression ratios are confirmed by using the regression formula,this is consistent with the new design code.