Consideration on the development of the seismic risk of an existing precast building after retrofot interventions

Many industrial buildings built in Italy until the 1980s and designed to non-seismic standards are located in areas of moderate seismic risk and need to be retrofitted to increase their seismic safety. The Italian technical standards provide the criteria for interventions and indications for the quantitative assessment of the seismic risk. They allow different levels of risk reduction through local, ameliorative and fully compliant interventions, and in all cases the safety assessment of the whole structure is mandatory. However, in the case of a global intervention, the codes do not require an assessment of the impact of the retrofit on the local response, i.e. on the connections between different structural and non-structural elements. The aim of this paper is to perform an analysis of the evolution of the seismic risk of a reference industrial building made of precast elements. Three different states of the structure are considered: the as-built state, the locally strengthened structure and the fully strengthened structure are studied. The impact of the retrofitting measures is verified by comparing the performance of the structure using a multi-stripe analysis in terms of the demand/capacity ratio associated with each vulnerability of the structural and non-structural system.