RECENT ADVANCES IN SEISMIC VULNERABILITY ASSESSMENT OF CROATIAN COASTAL URBAN AREA

The seismic vulnerability assessment of existing urban areas provides fundamental information about the process of reduction of seismic risk in different phases of planning and emergency management. This contribution presents recent advances in seismic vulnerability assessment in Croatian coastal areas at different scales, starting with a detailed analytical approach at the building scale to large-scale assessment at the building level and the level of the homogeneous zones. The investigation was performed in the City of Kaštela, a typical coastal settlement that has expanded over past centuries, resulting in a heterogeneous distribution of the buildings built in periods with different technical regulations. A detailed nonlinear-linear analysis of important buildings (historical, public) has been performed providing evidence of their collapse behaviour. A comprehensive hybrid approach to large-scale seismic risk assessment, combining seismic vulnerability indices with critical PGAs for different limit states, has been applied to define vulnerability curves that allow to relate vulnerability index, damage index and peak ground acceleration. The outcome of this analysis is large-scale risk representation in terms of the damage and seismic risk indexes at the building level. The level of seismic risk to the community depends on several other parameters whose activation reduces the resilience to extraordinary events. Considering the characteristics of the observed pilot site, additional criteria for the risk assessment of homogenous zones are, for instance, communal infrastructure, road network, construction density, inhabitation density, importance factor (public building, school, etc.), and status of protected historical buildings. A methodology for seismic risk assessment of the area at the level of the homogeneous zones is based on Spatial Multi-Criteria Decision Making and the PROMETHEE method. The presented approach for seismic risk assessment has important operational outcomes in the seismic risk management of the investigated area.