External Prestressing Concrete Columns with Fibrous Composite Belts

Synopsis: Five square columns were constructed to model shear-deficient columns and tested under constant axial compression and reversed cyclic lateral load, simultaneously. The retrofitting scheme consisted of wrapping the column along its end parts, i.e. around the plastic hinge area, by use of FRP in the form of three-centimeter wide belts. Both carbon and aramid/epoxy belts were used in this study. Moreover, for two of the specimens, the FRP belts were prestressed before applying the lateral load to the columns, and thereby, the effects of active confinement in addition to passive confinement were investigated. The proposed prestressing technique is an innovative method and can be applied manually. According to test results, while the original column exhibited brittle shear failure, all retrofitted columns developed ductile flexural response. Despite the different initial confining pressures, yet the same lateral stiffness of the confining device, the deformation ductility of all retrofitted columns was similar.