Towards damage-consistent performance-based design of critical infrastructures

The objective of earthquake-resistant design of critical infrastructures like nuclear power plants or lifelines is to ensure the prevention of catastrophic disasters. Experience from recent past like the earthquake of Amatrice (2016) or the Napa earthquake of 2014 have shown that traditional code requirements based on probabilistic seismic hazard maps are not able to prevent disasters. The purpose of probabilistic hazard assessment is to support risk analysis. The latter is used to separate tolerated residual risks from non-tolerable, more frequent risks. Therefore, these methods do not intend to provide protection against extreme events. Additionally, it is proven that the traditional hazard parameter used in probabilistic seismic hazard maps, peak ground acceleration (PGA), is not very suitable for the description of the physical impact of earthquakes on structures, systems and components. The only hazard parameter describing physical effects of earthquakes at least on macroseismic scale is intensity or in engineering units, intensity factors. The actual EMS-98 scale correlates reasonably well with the damage of structures classified into vulnerability classes. The availability of large databases of registered earthquake time-histories covering a wide range of site intensity values allows to model earthquake impact directly using dynamic time-history analysis methods. On this basis a methodology was developed that allows to design critical infrastructures for certain levels of seismic intensity directly. The methodology and some applications are presented.