A METHODOLOGY FOR DETERMINATION OF EFFICIENT EARTHQUAKE BINS FOR PERFORMANCE BASED SEISMIC DESIGN

For Performance Based Seismic Design applications, it is crucial to succeed in determining selected seismic input groups (bins) characterized by a defined and specific probability of occurrence (seismic hazard analysis). The seismic hazard analysis is generally performed by associating a probability of occurrence to a particular value of Intensity Measure (IM) and then by creating bins characterized by a specific value of IM. As pointed out in recent research works, special attention should be paid in determining bins which lead to dynamic structural responses (generally measured by Engineering Demand Parameters, EDP) characterized by a reduced variance of their maximum values. The more reduced the variance, the more efficient is the bin. Recently, different methodologies have been proposed to determine efficient bins on the basis of different (either scalar or vectorial) IM, such as Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV), Peak Spectral Acceleration (PSA). This paper proposes the use of computable and efficient bins characterised by a (1) a vectorial IM composed of PGA and PGV and (2) a specific relative ratio of near-field records to far-field records. In order to obtain such bins, it is here proposed a hazard analysis based upon the Cornell’s methodology and specialised (1) to account for completeness analysis, (2) to make use of specific attenuation laws which allows to obtain both PGA and PGV (e.g. the Sabetta-Pugliese law for the Italian territory) and (3) to obtain statistical information about the distance between the epicenter and the site of interest so to identify the relative ratio of near-field records to far-field records. The efficiency of such bins is here shown by means of specific numerical examples.