Iso-Class Curves for the Assessment of Seismic/Energy Retrofitting of an Existing Masonry Building through a Timber Frame System

Integrated interventions aim at improving both the seismic and the energy performance of existing buildings to optimize costs, environmental impact, and social consequences. This paper introduces the concept of iso-class curves for the selection of optimal integrated interventions, which provide the values of their economic costs and environmental impacts. The method is applied to a civil building located in Central Italy and hit by the 2016 earthquake, during which it exhibited a medium-high damage level with partial collapse. The building presents some critical aspects such as low masonry quality, in-plan irregularity, slender walls, openings close to corners, absence of structural connections and poor structural details. The seismic vulnerability and the energy performance are firstly assessed in the as-built configuration; afterwards, an innovative integrated retrofit consisting in a timber frame with OSB sheathing coupled with insulating panels is considered. The enhancement of seismic and energy performance is expressed through iso-class curves. These curves are easily readable by designers and owners to select the optimum intervention for the desired seismic or energy performance upgrade.