Retrofitting of a seismically deficient building

Most available seismic retrofitting methods have certain degree of difficulty to be implemented on site and are thus more expensive. A relatively new retrofitting technique coupling the conventional braces with the recently developed viscoelastic dampers is proposed to improve the seismic performance of deficient structures in more effective and efficient way. The relatively new damper is tubular in shape as opposed to the flat shape seen in the conventional dampers. The effectiveness of the proposed retrofitting technique is validated through the three-dimensional finite element analyses performed on real structures, in which three different brace configurations (diagonal, X and K) and small to strong earthquakes are considered. The vibration periods, interstorey drifts and formation sequences of plastic hinges are compared to each other between the original and the retrofitted structures. The study results show that the energy dissipation resulting from the proposed retrofitting scheme is significant, especially for X-type bracing systems. The proposed retrofitting method also alters the overall framing behaviour from strong beam–weak column to the more desirable strong column–weak beam. The retrofitted structure is shown to satisfy the modern seismic design requirements. The proposed retrofitting technique is also shown to be easier to be installed and cost-effective.