Search results for "prestressing"

showing 5 items of 15 documents

La variazione di schema statico nei ponti in cemento armato precompresso durante le fasi costruttive e l’influenza dei fenomeni lenti

2018

The construction of prestressed concrete bridges often presents different construction stages in which the structural static scheme changes many times, together with the characteristics of the construction elements. In fact, prefabrication and in situ assembly involve a multiple variation of the scheme with the introduction and removal of restraints, especially when temporary sup-ports are used. These transitional phases can strongly modify the structural behavior, in relation also to the deformations due to shrinkage and creep. In this study an evaluation of the effects of time-dependent phenomena is presented, for the case of complex sequences in which delayed restraints and removal of pr…

Settore ICAR/09 - Tecnica Delle CostruzioniBridge Creep Concrete Prestressing
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Safety assessment in N-M-V interaction of prestressed concrete elements subject to degradation of the reinforcements

2021

The estimation of residual life of viaducts and bridges is urgently topical, due to the age of Italian infrastructure network. Among the causes of reduced life of prestressed concrete structures, the role played by corrosion in prestressed reinforcements is fundamental. In fact, the reduction of the reinforcement cross-section with the formation of the outer layer of iron oxides and hydroxides and the bad filling of the ducts, induces an intermediate behaviour between that of external (unbonded) and internal (bonded) prestressing. For these reasons, the evaluation of degradation and its influence on structural safety cannot be neglected in the assessment of sections of existing structures c…

Settore ICAR/09 - Tecnica Delle Costruzionibridge prestressing corrosion concrete degradation
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Pannello precompresso di vetromattoni assemblati a secco per la realizzazione di involucri traslucidi

2012

L’invenzione riguarda la realizzazione di un pannello di vetromattoni montati “a secco” -da impiegare per la realizzazione di involucri edilizi traslucidi anche nel caso di edifici alti- che è in grado di rispondere adeguatamente alle sollecitazioni orizzontali (quali quelle dovute a vento e sisma) grazie all’applicazione della tecnica della precompressione mondirezionale. Per offrire una risposta ai limiti imposti dalla tecnica di assemblaggio tradizionale dei vetromattoni (“ad umido”), l’applicazione della precompressione consente, infatti, di dare ai pannelli preassemblati “a secco” una rigidezza adeguata anche in direzione normale al loro piano di posa, sfruttando le buone caratteristic…

The invention is related to the construction of a glassblock panel “dry assembled” that can be used to build translucent building envelope even in high-rise buildings. This panel is able to contrast the horizontal actions due to wind and earthquake by means of the application of unidirectional pre-stressing technique. To overcame the limits due to the “wet assembly” system traditionally used to assemble the glassblocks the use of prestressing technique allow the panels to have an adequate mechanical resistance against the actions perpendicular to their installation plane. In this configuration the mechanical resistance of the glassblocks is exploited. The unidirectional prestressing (along the prevalent dimension of the panel) is obtained through the grip of the nuts inserted in the steel bars that are housed inside the glassblocks supporting profiles positioned in the vertical cavities between the glassblocks and passing through the horizontal profiles useful to separate glassblock rows from each other. The proper nuts grip opposing to the steel plates positioned at the top and bottom of the panel allow to prestress the panel. The steel plate are positioned on a plastic plate fixed to the lateral faces of the glassblocks by means of resins.Settore ICAR/10 - Architettura Tecnica
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Fenomeni lenti nelle fasi di costruzione ed esercizio degli impalcati da ponte precompressi

2010

bridges creep prestressing
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Assessment and strengthening of reinforced concrete bridges with half-joint deterioration

2022

Existing Niagara-type concrete cantilever bridges, which in Italy are called Gerber bridges, suffer from degradation due to reinforcement corrosion and a consequent reduced load-bearing capacity. The assessment of these structures is therefore an important part of the procedures for analyzing the state of existing bridges and any interventions required for their retrofitting. In particular, safety against failure of the half-joint must be evaluated with respect to the behavior of the entire bridge and its state of conservation, determining what the conditions are that lead to failure, in terms of loads, state of stress, and possibly cracking state. This evaluation has to be carried out cons…

corrosionGerber saddleMechanics of Materialshalf-jointprestressingGeneral Materials ScienceBuilding and Constructioncantilever bridgereinforced concretestructural assessmentCivil and Structural Engineering
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