高轴压比下加芯混凝土框架柱延性与承载力试验研究

Experimental study on ductility and bearing capacity of concrete frame columns with central reinforcement under high axial compression ratio

通过高轴压比下8个加芯混凝土框架柱和1个普通混凝土框架柱低周往复加载的模型试验,阐述了主要试验现象及破坏形态,对各试件的P-Δ滞回曲线、位移延性系数、极限位移转角、屈服荷载和极限荷载等试验结果进行了研究,分析了加芯混凝土框架柱延性和承载力的影响因素。结果表明:通过对芯柱进行合理设置,加芯混凝土框架柱具有良好的滞回延性和较高的抗震承载力,可明显改善普通混凝土框架柱在高轴压比下的抗震性能,弹塑性变形能力能够满足抗震要求;芯柱的纵筋配筋率、截面面积和体积配箍率是影响加芯混凝土框架柱延性和承载力的主要因素。结合以往的研究成果,本文提出了加芯混凝土框架柱轴压比限值的建议值、正截面承载力计算公式以及相关设计建议。

Through the model test to eight concrete frame columns with central reinforcement and one general concrete frame column under high axial compression ratio and cyclic lateral loading , this paper described the major experimental phenomena and failure patterns , studied the test results of each specimen, including P-A hysteric loops, displacement ductility coefficient, ultimate displacement rotation, yield load, ultimate capacity of concrete frame columns with central reinforcement load , etc. The factors affecting the ductility and bearing were analyzed. The results show that, with reasonable arrangement of the core column concrete, frame columns with central reinforcement have excellent ductility and higher bearing capacity; seismic behavior of general concrete frame columns can be improved remarkably by central reinforcement so that their elasto-plastic deformation capacity can satisfy the seismic demands. The cross section area, longitudinal reinforcement ratio and volumetric tie ratio of the core column are the major factors affecting both ductility and bearing capacity of concrete frame columns with central reinforcement. In combination with past research results, this paper recommended the limit values of axial compression ratio, the formulas for calculating normal section bearing capacity and related design requirements of concrete frame columns with central reinforcement.