Search results for "seismic"

Dynamic Shakedown Sensitivity Analysis by Means of a Probabilistic Approach

2017

The shakedown limit load multiplier problem for elastic plastic structures subjected to a combination of fixed and seismic loads is treated. In particular, reference is firstly made to the unrestricted dynamic shakedown theory. The relevant seismic load history is modeled as a repeated one and, with reference to classically damped structures, appropriate modal analyses are utilized. With the aim of evaluating the reliability of the results arising from the application of the cited theory, a recent probabilistic approach is also utilized. This approach adopts the Monte Carlo method in order to define the necessary seismic acceleration histories and finally compute the related shakedown limit…

Stochastic seismic analysis of offshore towers

1984

After a brief review of the main problems and the most common analysis methods for offshore structures, a method of analysis for offshore towers submerged in water and subjected to strong earthquake motions is proposed. Nonlinear drag effects as well as random non-stationary seismic excitations are considered by means of a linearization technique based on a particular step-by-step procedure. Using a discrete lumped-mass model, the standard deviations of nodal displacements and velocities are evaluated. The probability of not exceeding a defined threshold of nodal displacements is also computed.

INNOVATIVE MASS-DAMPING-BASED APPROACHES FOR SEISMIC DESIGN OF TALL BUILDINGS

2021

Mass damping is a well known principle for the reduction of structural vibrations and applied in tall building design in a variety of configurations. With mass usually small (around 1% of building mass), the properly “tuned” mass damper (TMD) shows great effectiveness in reduc-ing wind vibrations, but minor advantages under earthquake excitations. The above limitation can be surpassed by utilizing relatively large mass TMD. For this pur-pose, two different solutions are here proposed. In both cases, the idea is to separate the building into two or more parts, thus allowing for a relative motion between them, and acti-vating the mass damping mechanism. In the first solution, the building is …

Statistical Picking of Multivariate Waveforms

2022

In this paper, we propose a new approach based on the fitting of a generalized linear regression model in order to detect points of change in the variance of a multivariate-covariance Gaussian variable, where the variance function is piecewise constant. By applying this new approach to multivariate waveforms, our method provides simultaneous detection of change points in functional time series. The proposed approach can be used as a new picking algorithm in order to automatically identify the arrival times of P- and S-waves in different seismograms that are recording the same seismic event. A seismogram is a record of ground motion at a measuring station as a function of time, and it typica…

Mud volcanoes as key-systems to investigate continental degassing and therole of seismicity on mass transfer

2018

The flow of fluids into the Earth’s crust can produce large-scale heat and mass transport. The mechanisms and driving forces for this fluid-transport range from molecular diffusion, to grain boundary diffusion and to advective flow. Recent studies [Torgersen,2010 and references therein] suggest that largescale vertical transport of fluids in the continental crust is likely advective and episodic. So it is crucial to understand if the variability of the measured degassing flux is a reflection of this episodic and advective transport. Here we try to answer these questions by using the noble gases. In particularly He that is recognized as a powerful tracer in variousfields, such as hydrology, …

Crustal structures of the Sicily orogene along the SIRIPRO seismic profile

2012

A crustal seismic profile across Sicily (Italy): preliminary results

2008

Seismic tomography tests applied to a gravity dam

2016

The control of the safety assessment of a dam is largely dependent on knowledge of the mechanical parameters of the actual construction, as well as its geological substratum. The application of geophysical methods can be used in existing dams to evaluate the materials (strength properties) and to verify if they match design expectations, as well as to contribute to the safety control. In particular seismics methods can considerably contribute to the examination indicating the less consolidated material and the degradation of mechanical parameters. For the characterization of the concrete conservation three seismic tomographies and a vertical seismic profile on the dam body were performed.Th…

Reti sismiche urbane per monitoraggio sismico monitoraggio strutturale ed allerta precoce

2021

In questa tesi, viene effettuato un analisi preliminare in cui si mette in evidenza come l'italia sia un paese a rischio sismico, poichè possiede molti centri storici con strutture non progettate per eventi sismici di media entità. Si è prestato molta attenzione su quante vite umane vengono salvate dopo un terremoto catastrofico. L'analisi fa emergere come, è importante essere tempestivi nell'estrarre le persone rimaste sotto le macerie, poichè la percentuale di persone estratte vive si mantiene alta solo entro le 48 ore dall'evento. Dopo 96 ore questa percentule si attesta a 0. In eventi passati spesso i soccorsi sono arrivati con giorni di ritardo nelle zone più devastate. L'obbiettivo ch…

Il terremoto del 1823 in Sicilia settentrionale: danni e ricostruzioni

2016

Il 5 marzo 1823 si verificò un terremoto che investì gran parte della Sicilia settentrionale. Numerosi danni si verificarono a Palermo, nelle aree limitrofe a sud e ovest della capitale, in alcuni centri delle Madonie e nelle zone situate lungo il litorale e l’immediato entroterra tirrenico da Palermo a Patti (in particolare a Naso). Il contributo intende indagare, attraverso lo studio delle opere degli autori coevi al sisma e soprattutto di una copiosa documentazione archivistica, le modalità attraverso le quali ci si raffrontò con i problemi determinati dal terremoto, dalla gestione dell'emergenza, all'analisi dei danni e delle successive ricostruzioni. Dal quadro tracciato emerge in part…