Seismic Upgrade of RC Deficient Frames

Recent earthquake observations and experimentation on reinforced concrete frames in which design lacked proper consideration of seismic loads, and which were constructed having non-compliance to modern building codes, have revealed the seismic vulnerability of such deficient frames. It is of vital importance that buildings built before the advent of modern codes or recently constructed and having construction defects due to poor construction practices must be strengthened using practical solutions, yet viable. A novel strengthening technique composed of three different types of haunches; i.e. rigid steel, deformable steel and reinforced concrete haunches installed at beam-column joints, was adopted to stiffen the frame connections and increase its lateral strength. Shake-table tests were conducted on 1:3 reduced scale 06 retrofitted RC frames using the 1994 Northridge earthquake accelerogram in order to understand the seismic behaviour of retrofitted frames, develop damage scale, obtain frames' response data for calibration of finite-element based numerical models and derive seismic response parameters i.e. over-strength factor, ductility factor and response modification factor.