Green Roof Retrofitting in Algeria Between Sustainability and Seismic Vulnerability

Installing green roofs in urban areas is a sustainable practice towards the ecological transition, they offer many advantages with regards to reducing energy consumption, mitigating the urban heat island effect, managing runoff ...etc. In order to propagate this technique, green roofs have to be installed on the top of existing buildings, which can increase their vulnerability during seismic events. The present paper aims to evaluate the impact of green roof retrofitting on the seismic performance of a collective housing in Algeria. To this end, the finite element method was adopted to investigate the seismic-related parameters according to the Algerian seismic regulations. The studied reinforced concrete building is located in the district of Constantine (northern east of Algeria). It was found that the presence of concrete walls, recommended by the Algerian seismic regulations, increases the rigidity of the building, which reflects positively on the building’s natural period and displacements. As for the stress-related parameters, the reduced normal force does not increase much; however, a significant increase in the shear forces at the base due to green roof implementation was observed. It was also found that adding a green roof contributes more to the stabilizing moment than to the overturning one during an earthquake event. Hence, in the studied context, the presence of load-bearing concrete walls offers certain positive effects on green roof installation with regard to the seismic performance. Nevertheless, a thorough seismic investigation should be performed before installing green roofs on the top of existing collective housing in Algeria.