1,721,096 research outputs found
Analisi di rischio a larga scala di ponti multicampata in c.a. con metodi agli spostamenti
No full textIn seismic countries, the managing authorities of road networks rely on risk assessment of bridges to decide retrofit intervention priorities on a regional scale. It is a current practice to assess seismic vulnerability in the form of fragility curves. The most extensively used tool currently available for the evaluation of vulnerability curves of large-scale systems is the Hazus methodology, which provides fragility curves for whole classes of structures, but shows deficiencies when applied to a community–specific database, where different typologies are represented.
Given the large number of bridges in a regional scale road network, fragility curves have to be obtained by means of simplified and reliable numerical methods, time-history analyses being to date still very expensive in computational terms when applied in a probabilistic framework. In the last decade displacement-based (DB) methods have become increasingly established simplified assessment procedures.
Present work reports on an extensive risk assessment study carried out on Northern-Italy’s Region of Veneto road system; the analysis focuses on one of the most typical bridge types of the network, multi-span RC bridges. Analytical fragility curves obtained with displacement-based approaches are proved to be sufficiently accurate. The curves obtained can be used as a reference for Italian and European RC multi-span concrete bridges
Innovative Joints with post-tensioned cables and dampers: analytical and numerical modelling
No full textThe innovative joints described in the present paper show rigidities comparable to those of welded joints and allow to dissipate the seismic energy in plastic field, even with small deformations, by means of particular elements. They are also able to self-centre the system at the end of the action of the cyclic loads through post-tensioned cables, avoiding plastic deformations in the column and the beam.
A general analytical method for the behaviour of innovative joints with post-tensioned cables and dampers has been validated through experimental results available in literature for two types of joints. The results were also compared with those deriving from a three-dimensional numerical model showing again a good agreement
Contributo degli irrigidimenti longitudinali alla stabilità di anime in travi metalliche da ponte
No full textLa memoria tratta l’analisi di instabilità lineare di lastre con irrigidimenti longitudinali in varie posizioni aventi differenti forme geometriche e soggette a forza assiale, flessione e taglio. L’obbiettivo è di fornire alcune regole pratiche sulla forma e posizione ottima di irrigidimenti longitudinali delle anime quando le stesse sono soggette a presso-flessione e taglio. Per mezzo di una estesa indagine numerica, si propongono delle indicazioni per il trattamento dell’instabilità di lastre irrigidite, tenendo in considerazione a) la dimensione e rapporto geometrico della lastra, b) le dimensioni e la forma della sezione dell’irrigidimento (sezione aperta e chiusa), c) la posizione dell’irrigidimento e d) la configurazione di carico (compressione uniforme, flessione pura, presso-flessione e taglio)
Conservation of walled towns - the experience of Padua
No full textGli atti sono stati pubblicati nel 2007. Non è stato possibile attualizzare il riscontro
Stabilità di pannelli forati soggetti a carico localizzato simmetrico: approccio sperimentale
No full textIn questo lavoro è descritta un’indagine sperimentale condotta su pannelli quadrati e rettangolari, con e senza fori. Il foro è posizionato al centro dei pannelli quadrati e sia nel punto di massimo e nodale della deformata critica corrispondente al primo modo di deformazione dei pannelli rettangolari. A ciascun pannello è stato applicato un carico localizzato simmetrico. Entrambi i pannelli quadrati e rettangolari sono stati realizzati con configurazioni geometriche snelle e tozze per osservare i diversi comportamenti in campo elastico e plastico
Conservation of modern rampart defensive walls - the experience of the city of Padua
No full textC. A. BREBBIA, Wessex Institute of Technology, United Kingdom & W. JAGER Technical University of Dresde
Stabilità di pannelli forati soggetti a carico localizzato simmetrico: approccio numerico
No full textIn questo lavoro è illustrata un’indagine numerica su pannelli quadrati e rettangolari, con e senza fori. Il foro è collocato al centro dei pannelli quadrati e sia nel punto nodale che di massimo della deformata critica corrispondente al primo modo di deformazione dei pannelli rettangolari. A ciascun pannello è stato applicato un carico localizzato simmetrico. Entrambi i pannelli quadrati e rettangolari sono stati realizzati con configurazioni geometriche snelle e tozze al fine di osservare i diversi comportamenti in campo elastico e plastico
“Experimental and numerical investigation of “Blockhaus” shear walls under in-plane cyclic loads.”
No full textBlockhaus systems represent a traditional construction technology where structural resistance is obtained by direct contact between multiple timber surfaces obtained via carvings, notches, and ancient joints. Native of forested areas, this technology is currently used for the construction of log buildings also in earthquake-prone areas. Their
seismic structural behaviour hence represents an interesting and not well-known research topic. In the paper, experimental results obtained by cyclic and monotonic tests recently performed on three different typologies of Blockhaus shear walls are presented and discussed. At the same time, sophisticated finite-element numerical models able to take into account the complex structural behaviour of log-walls subjected to in-plane seismic forces are described. Performed numerical simulations highlighted that in general multiple factors affect the global structural response of Blockhaus shear walls, including the presence of imperfections (small gaps) in the used timber joints, the contribution of friction phenomena, the mechanical properties of timber and the interaction between in-plane seismic forces and vertical permanent loads
“Experimental and numerical investigation of “Blockhaus” shear walls under in-plane cyclic loads.”
No full textBlockhaus systems represent a traditional construction technology where structural resistance is obtained by direct contact between multiple timber surfaces obtained via carvings, notches, and ancient joints. Native of forested areas, this technology is currently used for the construction of log buildings also in earthquake-prone areas. Their
seismic structural behaviour hence represents an interesting and not well-known research topic. In the paper, experimental results obtained by cyclic and monotonic tests recently performed on three different typologies of Blockhaus shear walls are presented and discussed. At the same time, sophisticated finite-element numerical models able to take into account the complex structural behaviour of log-walls subjected to in-plane seismic forces are described. Performed numerical simulations highlighted that in general multiple factors affect the global structural response of Blockhaus shear walls, including the presence of imperfections (small gaps) in the used timber joints, the contribution of friction phenomena, the mechanical properties of timber and the interaction between in-plane seismic forces and vertical permanent loads
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