1,721,378 research outputs found
Postfazione. Cosenza e la sua cattedrale nella scacchiera della storia
No full textConclusioni del convegno "Cosenza e la sua Cattedrale. Ambiente urbano e sede episcopale tra significati religiosi e secolari
A focus on the new italian guidelines for safety assessment of existing bridges (Key-note lecture)
No full textNew Italian guidelines for safety assessment of existing bridges were recently approved. This achievement was reached after the increasing number of casualites which clearly demonstrated the need for an in deep consideration of existing bridges. Actually, most of italian bridges already spent around 50 years of their service life and may require extraordinary repairs to achieve satisfactory safety levels according to latest code provisions. The guidelines represent an unprecedented document in the international context: they provide with additional analysis cases with different traffic loads and partial safety factors to be adopted in order to establish the bridge safety class at ultimate limit state. After introducing the main scope of the work, a preliminary case-study bridge with relative outcomes is proposed
Simplified non-linear analyses for fast seismic assessment of rc frame structures: Review and proposal
No full textWhen dealing with large scale seismic vulnerability assessment, usual FEM model based software cannot be a suitable choice to capture the lateral behaviour and seismic capacity of each of the several buildings located in that area. Approximate methods based on the fundamental of structural analysis could be more appropriate. They are practical due to their ease of use and capability to drive to results, even approximated, starting from few input data available. Therefore, they are especially suitable when the full knowledge of structural details cannot be available and the computational effort has to be strongly limited. This study presents the review of some simplified pushover methods available in the literature. Then a combined use of two approximate procedures, each addressed to a different aim, is proposed. These methods have been applied to RC frame structures, to preliminarily compare their effectiveness in simulating the “exact” results would come from a professional FEM structural software
Calculation of Stresses, Deformations and Deflections of R.C. and P.C. Elements in Service
No full textNTC2018: la nuova Norma Tecnica e le costruzioni in Cemento Armato
No full textLa parte delle Norme Tecniche riguardante il cemento armato dovrebbe essere oramai consolidata. In pratica ci sono invece ancora alcune novità significative.
La prima riguarda l’esplicita considerazione, per la prima volta, degli effetti del confinamento degli elementi.
Vengono, infatti, introdotte formulazioni specifiche per valutare gli effetti in termini di deformazioni ultime del calcestruzzo per tener consto delle staffe negli elementi di sezione rettangolare e circolare. Sarà così possibile valutare la duttilità degli elementi esplicitamente, aspetto determinante per quantizzare l’incremento della capacità specie per elementi presso-inflessi come i pilastri: era l’ultimo tassello che mancava al progettista per fare un calcolo completo non lineare; ed adesso l’allineamento con l’Eurocodice 8 è totale.
Un altro aspetto che indirettamente influenzerà in maniera significativa le valutazioni strutturali, in particolare in zona sismica, è l’introduzione di elementi di partizione “duttili”, per i quali il limite per gli spostamenti di piano passa da 0.5% a 0.75% dell’altezza di interpiano
INGEGNERIA CONCORRENTE PER LA SALVAGUARDIA DEI BENI ARCHITETONICI, STORICI ED ARCHEOLOINGEGNERIA CONCORRENTE PER LA SALVAGUARDIA DEI BENI ARCHITETONICI, STORICI ED ARCHEOLOGICI
No full textNapol
Seismic Response Analysis of An Irregular Base Isolated Building
No full textThis paper assesses the reliability of code-compliant linear and nonlinear dynamic analyses for irregular buildings with base isolation system (BIS). Comprehensive analyses are carried out for a case study comprising a large reinforced concrete multi-storey framed hospital with 327 high-damping rubber bearings. Spectral and time history (linear and nonlinear) analyses were performed on the three-dimensional (3D) finite element model (FEM) of the structure; simplified analyses were also conducted on single-degree-of-freedom (SDOF) systems. It is found that, at damageability limit state, the values of maximum interstorey drifts (d/h) computed with spectral analyses on the three-dimensional FEM range between 1/6 and 1/10 of the code limit (d/h = 0.33%); thus more stringent code limits should be required for buildings with BISs. The maximum floor acceleration is reduced by about 70% with respect to the ground acceleration (free field site); the acceleration profile is uniform along the height of the multi-storey frame. Threshold values of floor accelerations to assess the seismic performance of equipments in buildings with BIS are lacking. At ultimate limit state (ULS), spectral analyses provide values of actions and deformations that are less conservative than those derived through time history analyses. To perform reliable dynamic analyses of base isolated buildings it is crucial to select natural earthquake ground motions compliant with the fundamental period of vibration of the structural system. Nevertheless, it is not straightforward to select adequate natural strong motions in the catalogues available world-wide; buildings incorporating BISs possess periods of vibration which are generally higher than 2.0 s. As a result, distant and high-magnitude earthquakes are effective for base isolated buildings; nevertheless, such earthquakes are scarce in the seismic databases. The outcomes of the present study also demonstrate that simplified linear analyses tend to provide estimates of the response quantities, displacements of base isolators and base shear of the superstructure, which can be reliably employed at preliminary design stage. Spectral analysis results of the 3D model tend to match those of the SDOF systems, even for irregular superstructure, provided that modal mass participating ratios are greater than 85-90%. The results of spectral analyses on both SDOF and three-dimensional FEM envelope the outcomes of linear time historie
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