In countries directly affected by seismic phenomena, the assessment of vulnerability and seismic hazard throughout the territory plays a very important role, in order to minimize seismic effects on the population. Furthermore to effectively apply the performance based design approaches to seismic design it is necessary to accurately identify appropriate Intensity Measures (IM). This paper aims at illustrating a method for determining the probability functions (PDF and/or CDF) of the peak ground acceleration (PGA) and peak ground velocity (PGV) due to the seismic action at a specific site, over a given observation time, which, for Performance Based Seismic Design purposes can be used as vectorial Intensity Measures. The method is based upon the Cornell widely upheld methodology (1968), specifically updated to take into account the latest contributions in geophysics developed for the Italian territory. This methodology assimilates the occurrence of seismic events to Poisson processes and characterizes the magnitude return period of each seismogenetic area using the Gutenberg-Richter law (1954). At this regard, the authors propose the innovative use of the completeness analysis suggested by Mulargia, Tinti and Gasperini (1985) for the correct interpretation of the seismic catalogues. The method makes use of the Sabetta-Pugliese attenuation law (1987) which is developed for the Italian territory for both PGA and PGV. The method treats the distance of the site from the epicenter as a random variable, by subdividing the territory in circular sectors, annuluses and annulus portions. This treatment allows an exact determination of the PDF and CDF of PGA and PGV at the site. The statistical characterizations of PGA and PGV thus obtained feature the same accuracy. This allows to use the couples PGA-PGV (characterised by given probabilities of occurrence) as vectorial Intensity Measures in multi-input incremental dynamic analysis IDA (D. Vamvatsikos and C. Cornell, 2002) for probabilistic design approach in performance based seismic engineering. The paper presents also illustrative examples of how PGA and PGV can be used as an effective Intensity Measure.
Statistical Chacterisation of the Seismic Action (PGA and PGV) for Performance Based Seismic Design
TROMBETTI, TOMASO;GASPARINI, GIADA;SILVESTRI, STEFANO
2004
Abstract
In countries directly affected by seismic phenomena, the assessment of vulnerability and seismic hazard throughout the territory plays a very important role, in order to minimize seismic effects on the population. Furthermore to effectively apply the performance based design approaches to seismic design it is necessary to accurately identify appropriate Intensity Measures (IM). This paper aims at illustrating a method for determining the probability functions (PDF and/or CDF) of the peak ground acceleration (PGA) and peak ground velocity (PGV) due to the seismic action at a specific site, over a given observation time, which, for Performance Based Seismic Design purposes can be used as vectorial Intensity Measures. The method is based upon the Cornell widely upheld methodology (1968), specifically updated to take into account the latest contributions in geophysics developed for the Italian territory. This methodology assimilates the occurrence of seismic events to Poisson processes and characterizes the magnitude return period of each seismogenetic area using the Gutenberg-Richter law (1954). At this regard, the authors propose the innovative use of the completeness analysis suggested by Mulargia, Tinti and Gasperini (1985) for the correct interpretation of the seismic catalogues. The method makes use of the Sabetta-Pugliese attenuation law (1987) which is developed for the Italian territory for both PGA and PGV. The method treats the distance of the site from the epicenter as a random variable, by subdividing the territory in circular sectors, annuluses and annulus portions. This treatment allows an exact determination of the PDF and CDF of PGA and PGV at the site. The statistical characterizations of PGA and PGV thus obtained feature the same accuracy. This allows to use the couples PGA-PGV (characterised by given probabilities of occurrence) as vectorial Intensity Measures in multi-input incremental dynamic analysis IDA (D. Vamvatsikos and C. Cornell, 2002) for probabilistic design approach in performance based seismic engineering. The paper presents also illustrative examples of how PGA and PGV can be used as an effective Intensity Measure.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
