0000000000425966
AUTHOR
Arici M.
La variazione di schema statico nei ponti in cemento armato precompresso durante le fasi costruttive e l’influenza dei fenomeni lenti
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…
Prevenzione del degrado dei ponti in c.a.p. con la precompressione bilanciata. Il ponte funicolare
La trave e l'arco hanno comportamenti strutturali completamente differenti. La trave infatti, sotto l'effetto dei carichi applicati, ha un comportamento tipicamente flessionale mentre l'arco, grazie alla spinta e alla sua sua curvatura geometrica, può essere progettato con un comportamento funicolare a prevalenza assiale. Le strutture precompresse possono combinare intelligentemente questi due diversi comportamenti e la precompressione può essere favorevolmente utilizzata per trasformare la trave in una struttura funicolare, analoga ad un arco, con comportamento prevalentemente assiale. In questa nota viene presentata una filosofia di progetto per lo studio dei ponti a piastra precompressi,…
Safety assessment in N-M-V interaction of prestressed concrete elements subject to degradation of the reinforcements
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…