Harmonizing Seismic Performance via Risk Targeted Spectra: State of the art, dependencies, and implementation proposals

Design spectra are commonly defined for a constant value of hazard associated to an “ultimate” limit state (LS) reference, typically 10% in 50 years. Given specific structure, this approach results different limit-state exceedance risk levels even sites characterized by the same design peak ground acceleration (PGA), mainly because differences curve shape/slope. Instead, Risk Targeted maps (first applied ASCE7-10) suggest application suitable adjustment factors, so-called coefficients, order ensure uniform collapse across and buildings. Making use simplified single-degree-of-freedom (SDoF) structures several configurations vibration period ductility, we test effectiveness factors computed under assumptions matching target or, at least, harmonizing multiple buildings with respect LSs. Although is shown be only theoretically possible unachievable practice, claim that harmonization remains viable target, offer insights future adoption Spectra European code provisions.