1,721,004 research outputs found
Analisi adattiva per la valutazione del comportamento sismico di strutture intelaiate bidimensionali e tridimensionali in c.a
No full textL’affermarsi di metodi di verifica sismica basati su criteri prestazionali ha portato al notevole sviluppo di pro-cedure statiche non-lineari, che presentano innegabili vantaggi, soprattutto in termini computazionali, rispetto, ad esempio, ad analisi dinamiche non lineari.
Nel lavoro viene presentata una metodologia iterativa semplificata di analisi adattiva, per la valutazione del comportamento sismico di strutture tridimensionali. Obiettivo dello studio è una prima valutazione della effi-cacia di tale metodo adattivo nel cogliere aspetti dinamici delle costruzioni. La procedura adattiva è applicata a due strutture di riferimento (di cui una bidimensionale e l’altra tridimensionale) e le risposte ottenute sono confrontate con i risultati di analisi statiche convenzionali non lineari e analisi dinamiche incremental
Experimental behavior and analytical modeling of corroded steel rebars under compression
No full textThe durability of reinforced concrete structures can be sharply reduced by the corrosion of the steel rebars. This phenomenon is of great concern, since it is one of main cause of degradation in RC structures, almost in non-exceptional conditions. Furthermore, the corrosion effects can influence the seismic behavior, leading to dangerous strain localizations and variations of strength distribution and rotation capacity. This problem is amplified if, due to the corrosion of the reinforcement, longitudinal and/or transversal, the buckling of the steel bars takes place. Main aim of the paper is the evaluation of the influence of the corrosion on the compressive and buckling behavior of corroded steel reinforcement bars. At the scope, a comprehensive experimental survey has been planned and performed, for different values of steel bar length-to-diameter ratios and different amount of corrosion. Furthermore, based on the obtained outcomes, a simplified analytical model is developed for the definition of the constitutive relationships of corroded bars under compression. (C) 2019 Elsevier Ltd. All rights reserved
Seismic retrofitting of masonry rocking elements with composite rebars
No full textVulnerability of unreinforced masonry structures, characterized by an out-of-plane behaviour, represents a worthy research topic, as highlighted by recent seismic events. Different retrofitting techniques, based on the introduction of proper restraints, can improve their seismic response. In this study, the more common technique, consisting in the application of vertical steel ties, is revised considering the usage of FRP rebars. The vertical restraints, placed in a centred position, are characterized by an elastic-brittle behaviour. In order to evaluate the effectiveness of the analysed retrofitting technique, the dynamic equation of motion of the anchored rigid rocking block is numerically solved. A parametric analysis is carried out for two rocking mechanisms (two-sided or one-sided), by varying geometry of masonry walls, characteristics of the seismic input and material of the vertical restraint. The obtained results show an improvement of the element seismic capacity, with an increase of the collapse acceleration, depending on the masonry block slenderness. Furthermore, the height of the block adversely affects the strengthening effectiveness. Consequently, the examined technique appears appropriate only in case of small values of the height of the masonry element
Valutazione sperimentale del legame di aderenza acciaio-calcestruzzo in presenza di corrosione
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Seismic assessment methods for concrete gravity dams. 15th World Conference on Earthquake Engineering. Lisbon, Portugal, 2012
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Influence of the corrosion on the serviceability limit state of reinforced concrete beams
No full textAim of the paper is the evaluation of the influence of the corrosion of the steel rebars in reinforced concrete elements on the serviceability limit state, with particular reference to the control of the deformability, of the stress in the materials and of the crack width. At the scope the formulations suggested by the EC2 code are applied. The influence of the variation of the bond-slip law, due to the corrosion effect, is taken into account in the evaluation of the crack width. In particular the parameter introduced in the EC2 formulation accounting for the bond behaviour at the steel-rebar interface is calibrated with an analytical model developed by the authors
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