Among the currently employed methods for the analysis and the design of structures potentially subjected to seismic actions, nonlinear dynamics analysis is one of the most accurate in describing the structural behavior. These time-domain analyses allow to predict the response of every element of the structure, studying how they interact during the formation and propagation of damage. Numerous approaches have been proposed for selecting recorded accelerograms in order to obtain robust estimates of the structural response. The PSHA has got a fundamental role in the selection procedure, in fact the accepted process is to perform hazard analysis on selected ground-motion parameters, and use the hazard information for record selection and uncertainties propagation, aware that there is no single parameter capable of capturing all intensity, frequency content, and duration information that affect the elastic and inelastic response of soil-structure systems. All the most important seismic codes, allowing to adopt nonlinear dynamic analyses, prescribe the use of suites of accelerograms representative of the seismicity at the considered site and whose average pseudo-acceleration response spectrum is compatible with a given UHS in an appropriate period range. This calculation of the structural response may lead to wrong estimates when dealing with non-linear systems. In this paper we focused on the definition of a procedure for estimating the reference mean structural response associated to a desired return period for non-linear structures. We first defined attenuation relationships for the inelastic demand on various SDOF and MDOF structures and then performed PSHA using the obtained models. We obtained the interstorey drift levels with a 475 year return period: these were used as reference response and compared to the estimates of the average response obtained using spectrum-compatible suites of accelerograms with the same return period, selected according to different criteria. Following this approach we were then able to evaluate how the application of each of these criteria to the data-set affected the composition of the spectrum compatible suites of ground motions.
Valutazione dei criteri di selezione per accelerogrammi basati sulla spettrocompatibilità per l’analisi non lineare
LIGABUE, VERONICA;BURATTI, NICOLA
2013
Abstract
Among the currently employed methods for the analysis and the design of structures potentially subjected to seismic actions, nonlinear dynamics analysis is one of the most accurate in describing the structural behavior. These time-domain analyses allow to predict the response of every element of the structure, studying how they interact during the formation and propagation of damage. Numerous approaches have been proposed for selecting recorded accelerograms in order to obtain robust estimates of the structural response. The PSHA has got a fundamental role in the selection procedure, in fact the accepted process is to perform hazard analysis on selected ground-motion parameters, and use the hazard information for record selection and uncertainties propagation, aware that there is no single parameter capable of capturing all intensity, frequency content, and duration information that affect the elastic and inelastic response of soil-structure systems. All the most important seismic codes, allowing to adopt nonlinear dynamic analyses, prescribe the use of suites of accelerograms representative of the seismicity at the considered site and whose average pseudo-acceleration response spectrum is compatible with a given UHS in an appropriate period range. This calculation of the structural response may lead to wrong estimates when dealing with non-linear systems. In this paper we focused on the definition of a procedure for estimating the reference mean structural response associated to a desired return period for non-linear structures. We first defined attenuation relationships for the inelastic demand on various SDOF and MDOF structures and then performed PSHA using the obtained models. We obtained the interstorey drift levels with a 475 year return period: these were used as reference response and compared to the estimates of the average response obtained using spectrum-compatible suites of accelerograms with the same return period, selected according to different criteria. Following this approach we were then able to evaluate how the application of each of these criteria to the data-set affected the composition of the spectrum compatible suites of ground motions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
