芳纶纤维布约束钢筋混凝土框架柱的轴压比限值分析

基于约束混凝土的本构关系理论,对芳纶纤维布约束钢筋混凝土框架柱的受力特性进行分析,推导出芳纶纤维布约束钢筋混凝土框架柱截面在大、小偏心受压界限破坏条件下的轴压比,研究了纵筋等级、箍筋体积配箍率和芳纶纤维布体积配箍率对柱轴压比限值的影响,研究结果表明:芳纶纤维布和箍筋约束可明显提高混凝土的峰值应力与极限压应变,改善混凝土的受力性能;芳纶纤维布约束钢筋混凝土框架柱可明显提高其轴压比限值,芳纶纤维布和箍筋的体积配箍率越大,界限轴压比越大;抗震设计时,为了提高框架柱的延性,除了增大箍筋的配置外,尚应合理选用纵筋的直径和等级。

LIMITATION OF AXIAL-LOAD RATIO OF REINFORCED CONCRETE FRAME COLUMNS STRENGTHENED WITH AFRP SHEETS

The mechanical properties of reinforced concrete columns strengthened with AFRP(aramid fiber reinforced plastic) sheets are analyzed according to the constitutive law of confined concrete.The axial-load ratio on the cross sections of the reinforced concrete columns strengthened with AFRP sheets under the conditions of the limit destroy is deduced.The influence parameters,such as the longitudinal reinforcement strength,the volume fraction of transverse reinforcing bars and transverse AFRP sheets,to the limitation of axial-load ratio of reinforced concrete columns are investigated.It is stated that the peak stress and the limit strain of concrete confined with transverse reinforcing bars and transverse AFRP sheets are increased evidently and the mechanical properties of concrete are improved.The limit axial-load ratio of reinforced concrete columns strengthened with AFRP sheets is enhanced and increases with the volume fraction of transverse reinforcing bars and transverse AFRP sheets.In the earthquake-resistant design of columns,the placement of longitudinal reinforcement and transverse reinforcement should be considered together in order to increase the ductility of columns.