Search results for " seismic"

On the definition of seismic vulnerability maps in cross-border Mediterranean areas

2015

The chance to locate and quantify the major risks associated to natural catastrophic events on a territory allows to plan adequate strategies and interventions by civil protection bodies involved in local and international emergencies. The seismic risk depends most of all by the vulnerability of buildings belonging to the urban areas. For this reason the definition, by a deep analysis of the territory, of instruments identifying and locating vulnerability, largely favours the activities of institutions appointed to safeguard the safety of citizens. Seismic and hydro-geological risks constitute the major component of the activities involving assistance actions carried out by civil protection…

Numerical seismic performance of a rammed earth dwelling considering the use of a textile reinforced mortar system

Rammed earth buildings represent a considerable portion of the existing vernacular building stock of several countries and they are very common in the southern region of Portugal. The historical and architectural values of these constructions, along with their recognized high seismic vulnerability, have made the structural rehabilitation of earthen buildings a priority among the scientific community. Despite some recent studies, the prediction of the seismic response of these buildings is still a challenging task. This paper presents the results of a numerical investigation on the seismic behaviour of a representative rammed earth building located in Alentejo (South of Portugal). Numerical …

Variable Friction Dampers (VFD) for a modulated mitigation of the seismic response of framed structures: Characteristics and design criteria

2022

In this paper a new approach for the energy dissipation is discussed based on the use of Variable Friction Dampers (VFDs). The VFD device is borrowed from braking systems mechanical engineering, able to modulate its capability of dissipation, providing a constant pure friction force coupled with an additional (variable) damping force with the increasing of the displacement. Resorting to a previous study, the characteristics and the efficiency of the “braking” system in terms of reduction of the displacements and the restoring forces is described for SDOF systems under seismic excitations and compared with the performances achievable by classic constant friction dampers (CFDs). Then, a desig…

RC Masonry infilled frames: Experimental results and development of predictive techniques for the assessment of seismic response

2014

La presenza di tamponamenti in muratura all’interno delle maglie di strutture intelaiate induce, in presenza di azioni laterali, una sostanziale modificazione della risposta globale rispetto a quella dei telai nudi in termini di rigidezza, resistenza e capacità di spostamento. La tesi presenta i risultati di una campagna sperimentale su telai tamponati con diverse tipologie di muratura soggetti a prove di carico cicliche. Successivamente viene proposto un criterio per la modellazione semplificata del comportamento ciclico attraverso un macromodello a puntone diagonale equivalente. Una ulteriore indagine numerica è eseguita per valutare l'entità degli effetti locali dovuti all'interazione fr…

Full scale tests of the base-isolation system for an emergency hospital

2019

The paper presents the results of some full-scale tests regarding the base-isolation system of the emergency room building of the polyclinic hospital in Palermo (Italy). This building has been recently realized and its base isolation system is characterized by double friction pendulum isolators. Static lateral pushing tests were aimed at identifying fundamental mechanical properties of the whole isolation level (e.g. friction forces and stiffness) in order to verify the agreement with the design hypotheses. Further dynamic tests provided different displacements of the isolated base followed by the instantaneous release (snap-back tests), in order to verify the effectiveness, the mechanical …

Influence of lateral load distribution in estimation of target displacement and capacity demand by pushover analysis

2010

Two simplified adaptive load patterns for conservative estimation of seismic demand in 2D frames by pushover analysis are presented. The influence of load pattern in assessment of target displacement and distribution of demand along the height of the structure is investigated by comparing results of non linear history analysis, and non linear static analysis for eccentric braced frames. Numerical analyses show that the proposed load patterns provide safe estimation of the seismic response more accurately than load patterns proposed by seismic code.

Seismic response of steel frames with reduced beam sections

2003

This study concerns the effectiveness of weakening on the beams of fully and partially restrained connection steel frames in order to locate plastic hinges far from the joints. Two types of non-linear analysis, for geometry and constitutive law are developed: static pushover analysis, in which the structure is subjected to constant vertical loads and to horizontal loads linearly increasing up to collapse; and incremental dynamic analysis, in which the structure is subjected to uniformly scaled ground motions. Applications for four-bay frames with three and nine stories designed according to the EC3 code and for Italian 1st-category seismic areas are developed in order to evaluate the influe…

Dissimilarity Measures for the Identification of Earthquake Focal Mechanisms

2013

This work presents a study about dissimilarity measures for seismic signals, and their relation to clustering in the particular problem of the identification of earthquake focal mechanisms, i.e. the physical phenomena which have generated an earthquake. Starting from the assumption that waveform similarity implies similarity in the focal parameters, important details about them can be determined by studying waveforms related to the wave field produced by earthquakes and recorded by a seismic network. Focal mechanisms identification is currently investigated by clustering of seismic events, using mainly cross-correlation dissimilarity in conjunction with hierarchical clustering algorithm. By…

Comparison between nonparametric and parametric estimate of the conditional intensity function of a seismic space-time point process

2008

A seismic gap can be defined as a segment of an active geologic fault that has not produced seismic events for an unusually long time; gaps are often considered susceptible to future strong earthquakes occurrence and therefore their identification may be useful for predictive purposes. In this paper we try to identify gaps in an area of South Tyrrhenian Sea by comparing the observed seismicity, estimated by nonparametric method, and the theoretical one, described by a particular space-time point process (ETAS model).

A smeared seismicity constitutive model

2004

The classical application of rate and state dependent frictional constitutive laws has involved the instabilities developed between two sliding surfaces. In such a situation, the behaviour and evolution of asperities is the controlling mechanism of velocity weakening. However, most faults have a substantial thickness and it would appear that it is the bulk behaviour of the fault gouge, at whatever scale, that is important. The purpose of this paper is to explore how bulk frictional sliding behaviour may be described. We explore here the consequences of applying the rate and state framework initially developed to describe the frictional behaviour at the interface between two interacting slid…