Assessment for behavior of axially loaded reinforced concrete columns strengthened by different patterns of steel-framed jacket

Rehabilitation, upgrading, or strengthening of structural members, especially columns, has become the target of many researchers because columns are the most important members in a building and the failure of columns causes direct collapse in the building. This study aims to get an assessment of the best pattern of steel-framed jacket used for strengthening axially loaded concrete columns by numerically studying the behavior of the column for different cases of the same amount of steel jacket. The jacket consists of four angles and/or battens, lacings, or battens with lacings. The nonlinear analysis program designated as ARCC-SSJ (Analysis of Reinforced Concrete Columns Strengthened by Steel Jacket) is used to compare different patterns with the same and different cross-sections of battens and single lacing, as well as battens and lacing with battens taken into account. It is found that lacing with battens is the best pattern for the same amount of steel jacket with different cross-sectional areas. It is observed that the load-carrying capacity of the column increased by approximately 1.8 and 1.15% over that of battens alone in the case of a lacing angle of 60.832 degrees and 74.407 degrees with the vertical axis of the column, respectively.