Combined seismic plus energy retrofitting for the existing RC buildings: Economic feasibility

The vast majority of the existing European building stock has been built without modern provisions for earthquake resistance and energy efficiency, resulting in seismic vulnerable and low energy performance buildings. Although many studies to address both these needs exist, energy and seismic retrofitting are nowadays treated separately. In this study, a combined seismic and energy retrofitting approach is adopted. Retrofitting strategies for existing RC buildings, combining seismic and energy features are investigated and compared. For what concerns seismic retrofitting, two different seismic retrofitting techniques for RC-moment resisting frames, namely addition of RC Walls and TRM Jacketing). The economic benefit deriving from their implementation has been evaluated using a probabilistic vulnerability building based approach (based on fragility curves and mean repair costs). Moreover, a simplified method for fragility curves in retrofitted state has been proposed. For what concerns energy retrofitting, an attempt was made to evaluate the energy performance and cost improvements of buildings receiving various thermal insulation materials (i.e. EPS, XPS, PUR) to their building envelopes, following a simplified procedure in line with the requirements of the Italian regulation. To evaluate the economic feasibility of an integrated seismic plus energy retrofitting approach, this paper proposed an expected annual loss (EAL) parameter combining both the economic benefits related to reduction of the seismic risk and energy losses. It was found that a number of retrofitting techniques were effective and economically feasible, with the combination of advanced textile composites (i.e. TRM) and thermal insulations materials (i.e. EPS) being the most effective scheme, than the combination based on more localized seismic interventions. Overall, this study demonstrates that the concurrent energy and seismic retrofitting using advanced materials is a quite promising alternative approach for upgrading the existing RC buildings in seismic EU regions.