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.