Insitu steel jacketing of reinforced concrete columns : a study in beam-column junction effects

Abstract

Strengthening of columns in buildings by retrofit steel jacketing is a widely developed procedure enabling this element to carry a heavier load. However, the effect on beam-column junctions is often overlooked when analysing and applying this technique. In view of this, this body of research aims at analysing the behaviour of beam-column junctions when the latter is subjected to column axial loads. This experimental investigation was carried out using scaled-down test samples, which were loaded to failure. Four sample types were investigated; two column types having different mid-height stirrup layouts and two beam- column junction cast types having different quantities of beam stubs employed in the central region, such that all this enabled concrete confinement in the central area to be built up in stages. These four specimen types are further divided into steel jacketed and steel end-capped, the latter being for control purposes. It was found that the added confinement brought about by the steel jackets showed a general increase in load capacity of the specimens, this being more amplified in samples having a lower concrete grade.c