1,721,026 research outputs found
IL TERREMOTO DEL 1980, RISCHIO SISMICO E PREVENZIONE. Ricerca e sperimentazione dell’Università degli Studi della Basilicata.
No full textIl 23 novembre del 1980 un terremoto del decimo grado della scala Mercalli (magnitudo
6,9) devastava una vasta area compresa tra la Basilicata e la Campania, provocando circa 3000 vittime. L’evento sismico, compromettendo buona parte del patrimonio edilizio e delle attività economiche presenti nell’area colpita, mostrava la grande fragilità del nostro territorio e l’enorme difficoltà del Sistema Italia dell’epoca a reagire prontamente a fronte di eventi calamitosi di così grande portata. Per la prima volta in Italia si avviava un processo di revisione dei meccanismi e delle procedure di approccio alle grandi calamità che portò, da una parte, alla nascita dell’attuale sistema di Protezione
Civile Nazionale, dall’altra determinò un impulso significativo verso gli studi per l’approfondimento della conoscenza sulla sismicità del territorio italiano e la messa a punto di tecniche sempre più efficaci di mitigazione del rischio sismico per strutture ed infrastrutture. Con l’approvazione della legge 219 del 1981, che regolamentò il processo di ricostruzione delle aree colpite dal sisma, si avviò, di fatto, anche il progetto di istituzione dell’Università degli Studi della Basilicata. Tale atto, espressione della volontà di rinascita della Basilicata a fronte di una tremenda catastrofe, rappresentò il punto di partenza di un processo che, alla luce dei risultati raggiunti, può essere definito sicuramente virtuoso, sebbene non del tutto completato. Il territorio ferito
dal terremoto si avviava, dunque, a diventare sede di un centro di studi e formazione scientifica specializzata in diverse discipline, tra cui quella dell’ingegneria sismica, contribuendo, così, alla ricerca e allo sviluppo di tecniche per la realizzazione di un patrimonio edilizio più sicuro ed una società più resiliente. Si individuava, contestualmente, un efficace strumento di sviluppo economico e di sbocco lavorativo per tanti giovani lucani. A distanza di 40 anni dal disastroso terremoto, questo lavoro prova a delineare un quadro aggiornato sullo stato di avanzamento della ricerca nel settore della riduzione del rischio sismico e della prevenzione, facendo particolare riferimento al contributo fornito dall’Ateneo Lucano
Effect of Over-Stroke Capacity of Curved Surface Sliders on the Collapse Safety of Seismically Isolated Buildings
No full textRetrofitting of R.C. Buildings by Energy Dissipating Bracing: Numerical Simulations and Comparison with Experimental Tests
No full text
Rafforzamento delle strutture murarie: il sistema CAM di cuciture attive per la muratura
No full textPotenza-Mater
Prove sperimentali di isolatori elastomerici: influenza del carico verticale V e del fattore di forma secondario S2.
No full textSeismic Behavior and Modeling of Ductile Composite Steel-Trussed Concrete Beam to Column Joints
No full textThis paper presents an experimental and numerical study on a ductile beam-column connection between a composite reinforced concrete truss (CRCT) beam and a reinforced concrete (RC) or concrete-filled tube (CFT) column subjected to bending and shear loads. Two experimental models with different beam-column joint testing schemes, extracted from the same prototype three-dimensional structure designed according to the rules of the capacity design provided by seismic code, were subjected to quasi-static cyclic tests by applying gravitational loads and the horizontal seismic force. The main objective of this paper is to verify the ductile behavior of both specimens experimentally and to simulate the experimental global and local responses by nonlinear static analysis, considering different modeling approaches. The comparison between the experimental and numerical results highlights, for both models considered, the ductile and dissipative capacity of the connection system, designed following the criteria of the hierarchy of resistances proposed by the current Italian code. The results of different experimental setups demonstrate that the tests can be repeated and the results can be reproduced by means of simple nonlinear model
Improving the earthquake resilience of isolated buildings with double concave curved surface sliders
No full textThe underlying concept of base isolation is the uncoupling of the horizontal building movement from ground motions using a flexible isolation layer made with either elastomeric or sliding bearings. Double Concave Curved Surface Sliders DCCSS are seismic isolators based on the pendulum principle. DCCSS isolators that do not include any mechanical elements that serve as end-stops coherently with European codes, for earthquakes stronger than the ultimate limit state ones, the inner slider runs on the edge of the sliding surfaces beyond their geometric displacement capacity (over-stroke regime) preserving the ability to support gravity loads. This paper focuses on the effects of the over-stroke displacement of DCCSS and of displacement restrainers on the seismic response of base isolated buildings considering a case study. At the first stage of testing, the numerical model of the bearings over-stroke behavior has been calibrated on an experimental displacement-controlled test carried out in this study, also considering few results available in the literature. Nonlinear static and dynamic analyses including inelastic superstructure and different basic isolation system models, with and without over-stroke effects and with and without strong end-stroke restraints, have been performed. The parametric analysis aims to estimate annual frequencies of exceeding the superstructure yielding limit when the isolators reach the maximum displacement varying end-stroke and over-stroke parameters
Base isolated buildings with curved surface sliders including displacement restraints
No full textSummary. Recent researches on seismic isolated structures are focused on the behaviour of isolation devices when extreme loading conditions are applied, with displacement demands higher than the design value [1]. Generally, the design displacement is considered as the collapse limit and no further capacity is taken into account [2]. This study investigates the effects of the presence of displacement restraints on the response of seismically isolated buildings based on Double Curved Concave Surface Sliders (DCCSS) for displacements larger than the design values. Two residential buildings case studies are considered with moment resistant steel or reinforced concrete frames both isolated with DCCSS [3] [4]. The isolated structures satisfy prescriptions of the current Italian seismic code considering the same seismic actions for the site of L’Aquila. Pushover analyses are carried out in order to estimate the engineering demand parameter (Superstructure Global Drift) limit values used for the definition of the superstructure failure condition. The effects of the impact of the isolation systems against retaining elements on the seismic response of isolated structures are highlighted. The results of multi-stripe analyses using twenty ground motions at ten different seismic intensities [5] are compared. © 2021, Scipedia S.L. All rights reserved
Shaking table tests on reinforced concrete frames without and with passive control systems
No full textAn extensive experimental program of shaking table tests on reduced-scale structural models was carried out within the activities of the MANSIDE project, for the development of new seismic isolation and energy dissipation devices based on shape memory alloys (SMAs). The aim of the experimental program was to compare the behaviour of structures endowed with innovative SMA-based devices to the behaviour of conventional structures and of structures endowed with currently used passive control systems. This paper presents a comprehensive overview of the main results of the shaking table tests carried out on the models with and without special braces. Two different types of energy dissipating and recentring braces have been considered to enhance the seismic performances of the tested model. They are based on the hysteretic properties of steel elements and on the superelastic properties of SMAs, respectively. The addition of passive control braces in the reinforced concrete frame resulted in significant benefits on the overall seismic behaviour. The seismic intensity producing structural collapse was considerably raised, interstorey drifts and shear forces in columns were drastically reduced
- …
