Implementing Conditional Hazard for Earthquake Engineering Practice: The Italian Example

In the last years, among those for which seismic hazard is available, researchers have identified spectral acceleration Sa(T1) at the first mode period of the structure as one of the most convenient intensity measures (IM) for seismic analysis of engineering structures. However, there are cases in which alternative IMs have been found to be also important to complement the structural response information carried by Sa(T1). To account for them in a complementary manner, the concept of conditional hazard maps was introduced recently. It consists in maps of percentiles of a secondary IM given the occurrence or exceedance of a primary parameter, for which a design hazard map is already available (as it often happens for  Sa(T1)). In this paper, the conditional hazard concept is exploited further and maps, for some emerging IMs, are computed for the whole Italian territory. Results demonstrate how conditional hazard renders the use of vector-valued IMs easy and practice-ready, at the sole cost Sa(T1) is considered the primary IM, which in fact is the underlying hypothesis in several codes.