New seismic risk index for existing buildings

The assessment of the seismic vulnerability of existing buildings (in particular for public or strategic) is frequently based on strongly simplified methods than those used for new or retrofitting design at least for the first evaluation. In particular, the seismic performances are often summarized by simple and poor indexes, incorrectly called seismic risk indexes. For example, the seismic risk index provided from several standard code or guidelines for practice are based on simplified and deterministic procedure. Moreover, the evaluation of the reference seismic intensity is generally based on simplified model. In this work, these limitations are highlighted and overcame. A new and probabilistic approach to define a more accurate Seismic Risk Index (SRI) for existing building is proposed. The novel SRI is based on reliable and analytical Fragility Curves.