Seismic retrofitting and new way of living in existing social housing settlements

Irpinia’s earthquake of 1980 induced a significant upgrade in Italian anti-seismic regulations, confirming the use of correcting the risk after it became emergency. Seismic retrofitting just can be a solution for this bad routine, aiming to realize a wide securing, not only for few public structures, but also for residential buildings; in fact we have to consider that in Italy a great part of the edifices realized with a reinforced concrete structure were designed during 60’s and 70’s, without any anti-seismic standard, only thought for vertical loads. Vulnerability of these buildings is just to evaluate, also considering that they show the effects of time. Italian Law 1/2011 (Piano Casa Campania) suggested a possible solution, offering volumetric bonus for those construction works connected to an energetic up-grade, to which also seismic retrofitting could be joined. Such incentives, together with tax deductions, can be a spring for a wide work of renovation. Nowadays many methods for seismic reinforcement are available, both for works spread to all the elements of the structure, such as strengthening of pillars and beams with FRP (Fiber Reinforced Polymers) or with CAM system by steel elements, and for punctual actions on few elements, like insertion of friction pendulum bearings, damping rubber bearings or hysteretic bracing systems, that can much reduce time and problems of construction site. However it’s an error to think that these interventions must be limited to themselves, without considering possibilities they offer and qualities they must show. In fact, if we consider that a construction site has an high cost and always involves some bothers for the inhabitants, it appears reasonable to convert these problems in an opportunity to improve the building also in an architectural way, involving facades (including energetic upgrade) and internal arrangement. Integrated works of rehabilitation spread all around Europe, we can think to Tower Bois-le-Prete by Druot e Lacaton&Vassal, where the use of prebuilt elements (without entering inside the edifices) deeply changes internal spaces, creating a new relation inside-outside, but above all, offering possibility of easy future changes thanks to prefabrication, also maintenance gets fast and basic. This paper proposes a method for architectural requalification and seismic retrofitting of social housing based on the use of shear metal panels to stiffen the structure, to which is connected substitution of external walls with prebuilt panels of fixed dimensions. Some of the panels include metal plates to increase resistance to horizontal forces due to the earthquake, and they can’t be substituted with other closing panels, because they have to offer structural continuity, after an earthquake metal plates can be easily changed, because they are the only element suffering a deep deformation, while the frame that contains it remains in an elastic state. Facades are made by prebuilt panels of wood layers on steel frames filled with thermal insulation; they can be easily changed to allow substitution of closed panels with a window, a bow/window, etc., according to changes in internal arrangements; only a mobile crane is required to change facades, this offers a real flexibility for the inhabitants. They also have a structural goal, in fact one or two new floors can be realized on the top of the building, in order to realize cooperative dwellings for singles, who have difficulties to find an exact solution for their needs. New floors can also be used to replace apartments placed at ground level, that often offer inadequate living conditions cause of their urban collocation. Many old popular buildings, realized in peripheral places, as time passes by, are now in central position, having good fair value, so that floor apartments, whose inhabitants are replaced on the top, can be leased to young freelancers at a low cost, so compensating the prize of building works. This method was developed during a PhD research entitled ‘Architectural requalification and seismic retrofitting of social housing’ held inside ‘Structural engineering and construction and urban renewal’ PhD School in University of Salerno, and related themes were published in the PRIN Project ‘Integrated approaches for the sustainable rehabilitation of social housing settlements in South Campania. Social demand, way of living and new dwelling typologies’.