Hinged-wall solutions for the structural strengthening of existing RC buildings

The reinforced concrete (RC) constructions built after World War II represent almost half of the European building stock. Such buildings are characterized by low energy efficiency, living discomfort, and may be inherently vulnerable to seismic actions, having been designed before the enforcement of modern building codes. A multi-purpose retrofit strategy addressing in particular both energy and structural issues is therefore necessary. The present paper considers the sole seismic retrofit interventions by investigating the suitability of external RC walls hinged connected at their base, suitable to improve the seismic performance of poorly detailed existing RC buildings. In particular, such a solution avoids the concentration of deformation at one storey of the building, i.e. the development of soft story mechanisms, and reduces the demand on the foundations of the new system, being the bending moment at the base of such walls nearly zero. The paper shows, through non-linear pushover analyses on 2D frames, how the hinged wall solution is suitable for enhancing the seismic performance of existing buildings both in the case of strong-column weak-beam or strong-beam weak-column characteristics