Experimental & theoretical analysis for strengthened columns

Although, reinforced concrete jackets is the most usedmethod for strengthening reinforced concrete columns, it wasfound that there were some difficulties in constructing thesejackets at the top of the columns. So that, the height of thejacket was found to be lower than the column’s height andmaximum tensile strain in the R.e. jacket occured very closeto its upper end causing longitudinal cracks started from thetop of the jacket. Researchers investigated various parametersaffecting the strength of the strengthened columns.In this study, a new technique for reducing the lateralstrain at the top of the R.e. jacket was introduced. This wasachieved by confining the top of the original column by steeljacket in addition to the R.e. jacket. Two variables wereconsidered, the deptb and thickness of the steel jacket. Thebehaviour of the strengthened columns using steel jackets wereinvestigated experimentally on 24 real concrete models andtheoritically using the finite element method.Results showed that the ultimate capacity of the columnswas increased considerably by using steel jackets in additionto the R.e. jackets. Significant curves and conclusions wereobtained.