Abstract
Fibre Reinforced Polymers (FRP) confinements on square and rectangular sections behave differently from confined circular sections. Confining inward pressure over the entire circular section is uniform, whereas in non-circular sections confining pressure development is inconsistent. As a result, these sections could be divided into the distinct properly and partially confined areas. Presence of these partially confined regions would much reduce influence of FRP confinements to increase concrete’s peak strength and ultimate strain. To evaluate confinement effectiveness, effect of mentioned areas must be taken into account precisely. This paper describes a theoretical model adapted to seismic strengthening and retrofit of the square section RC columns confined with advanced composite materials. The model is the author’s earlier proposed one calibrated with cautious survey on the existing test data. This model takes into account geometrical parameters of the column shape such as overlapping length and corner rounding radius; furthermore both concrete and FRP confinement mechanical properties. Finally it proposes a new shape factor for the square sections which plays a major role in effectiveness evaluation of FRP confinement. Keywords: Fibre Reinforced Polymers, square section, Reinforced Concrete columns, strengthening