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Hemp Cables, a Sustainable Alternative to Harmonic Steel for Cable Nets
Full text linkRecent developments in the field of materials engineering have allowed for the use of natural materials for common structural elements, instead of traditional materials, such as steel or concrete. In this context, hemp is a very interesting material for structural building design. This paper proposes the use of hemp cables for roofs with hyperbolic paraboloid cable nets, which sees the use of a sustainable material for structure, thus having a very low environmental impact, in terms of structural thickness and amount of material. The paper discusses five different plan sizes and two different hyperbolic paraboloid surface radius of curvatures. The cable traction, which gives the cable net stiffness, was varied in order to give a parametric database of structural response. Three dimensional geometrically nonlinear analyses were carried out on different geometries (i.e., 10), cable net stiffnesses (i.e., 8), and materials (i.e., 2). Traditional harmonic steel and hemp cables are compared, in terms of vertical displacements and natural periods under dead and permanent loads
Modeling non-linearity on cable stayed masts of tensile fabric structures
No full textTensile membrane structures are part of a unique technology that gives designers the capability to experiment new forms and new solutions to conventional design problems. These structures are extremely efficient for long span application and allows considerable savings in the foundations and supporting structure costs. Cable stayed masts are integral part of this structure typology and consists of a inclined elements supported by several layers of pre-tensioned cables. Generally their dynamic loading is not a concern in the design of tensile structures, nevertheless in case of massive shafts, their dynamics can play a fundamental role for global behaviour of the structure. Therefore pre-tensioning force on supporting cables system is an important issue since the internal force distribution, significantly affects their structural dynamic behaviour. A non-linear cable model, combined with the taut-cable theory has been employed to simulate the non-linearity conditions in the stays and cables, by using a restoring-force equivalent spring model to replicate the behaviour of each cable. In the present paper a simplified based displacement technique is utilized to examine the non-linear dynamics of the system. The proposed approach, based on energetic method Equivalent Linearization method (ELM), shows a robust simplified technique capable to linearize the non-linear system, taking into account of slackening effects of pre-tensioned stays. It is concluded that performance coefficient and linearized frequency, may possibly be used as useful indicators for designing pre-tensioned cable stayed masts where a suitable selection of the initial pre-tensioning force can effectively improve dynamic performance of the system
Parametrical DesignTrends for a Hyperbolic Paraboloid shaped over a square plan: Vertical Displacements and Natural Periods
No full textTensile structures are one of the most convenient solutions for covering large spans. For both temporary and permanent uses, they are optimal as sport arenas, meeting rooms or concert halls. However, codes and literature neglect these structures thus making it difficult to carry out preliminary designs for this structural typology in order to estimate the cost-benefit ratio compared to others. On the contrary, parametric equations used to preliminarily estimate the static and dynamic behavior of these structures are useful to designers. In order to give parametric information about some examples of these structures, this paper investigates the initial natural frequency and vertical displacements under dead and permeant loads of cable nets, with a hyperbolic paraboloid shape and square plan, depending on geometry. In total, two curvatures of a hyperbolic paraboloid surface and five different plan sizes are calculated with eight different cable tractions in order to give design trends. The trends are illustrated with an error bar resulting from the variation between different tractions considered for each geometry. The results are useful to preliminarily estimate the cost and the range of interference between wind and structure
Parametrical design trends for a hyperbolic paraboloid shaped over a square plan: Vertical displacements and natural periods
No full textTensile structures are one of the most convenient solutions for covering large spans. For both temporary and permanent uses, they are optimal as sport arenas, meeting rooms or concert halls. However, codes and literature neglect these structures thus making it difficult to carry out preliminary designs for this structural typology in order to estimate the cost-benefit ratio compared to others. On the contrary, parametric equations used to preliminarily estimate the static and dynamic behavior of these structures are useful to designers. In order to give parametric information about some examples of these structures, this paper investigates the initial natural frequency and vertical displacements under dead and permeant loads of cable nets, with a hyperbolic paraboloid shape and square plan, depending on geometry. In total, two curvatures of a hyperbolic paraboloid surface and five different plan sizes are calculated with eight different cable tractions in order to give design trends. The trends are illustrated with an error bar resulting from the variation between different tractions considered for each geometry. The results are useful to preliminarily estimate the cost and the range of interference between wind and structure
New Wooden Structures with Composite Material Reiforcements for the re-buildings of the Arena flooring in the Colosseum
No full textSono evidenziati tutti gli aspetti della progettazione dell’intervento per un restauro strutturale tanto complesso (come è stato per le nuove strutture lignee dell’arena del Colosseo), incluso quello sperimentale per le travi. In particolare la ridotta dimensione disponibile in relazione alle esigenze dell’archeologia (sfioramento e allineamento con le strutture antiche,attestazione del piano finito dell’arena alla quota antica) richiede o l’impiego dell’acciaio (rifiutato in questo contesto monumentale per motivi storici) o di altro materiale altrettanto resistente; la scelta, essendo l’originario calpestio dell’arena di legno, non poteva non privilegiare ancora il legno, opportunamente rinforzato. Per la creazione di travi resistenti e sufficientemente rigide sono stati integrati più moduli di legno lamellare, affiancati a lastre di compensato, rinforzate con barre pultruse di fibre di carbonio, e solidarizzate poi con sistemi multi direzionali di fibre aramidiche (no fabric) incollate con resine. Le prove di laboratorio sui prototipi e le prove di carico in sito sono state in accordo con le previsioni di progetto e hanno confermato l’elevata resistenza e la ridotta deformabilità delle travi, pur essendo stato necessario contenere la loro altezza
THE STRUCTURAL BEHAVIOUR OF COLOSSEUM OVER THE CENTURIES
No full textLe vicende che hanno accompagnato il Colosseo fino al raggiungimento dell’attuale conformazione mutila e dissestata, vengono interpretate alla luce della storia; non è escluso che i primi dissesti siano stati determinati da un effetto sinergico tra l’incendio del III secolo (proposto generalmente come causa diretta), l’assestamento della fondazione (prolungato nel tempo sotto la grande mole della costruzione) e i quasi contemporanei eventi sismici avvenuti. Questi furono di intensità modesta ma sufficiente per determinare il crollo lungo la cavea fino all’arena delle colonne dell’attico (ormai rese semplicemente appoggiate dopo la devastazione delle travi lignee del portico, bruciate nell’incendio), rovesciate dal terremoto. Le analisi strutturali eseguite suggeriscono questa possibilità
New Wooden Structures with Composite Material Reinforcements for Historical Buildings. The case of the arena flooring in the Colosseum
No full textGli aspetti strutturali della ricostruzione del piano dell’arena, unitamente alle tecniche costruttive innovative impiegate per realizzare le travi lignee, di altezza ridotta in relazione alle luci ed ai carichi imposti, vengono discussi con gli specialisti convenuti in un congresso internazionale, appunto dedicato alle tecniche innovative introdotte per la produzione di strutture di legno
Analysis an historical and structural point of vieuw of the domes of Pantheon, Hagia Sophia and St Peter.
No full textLe analisi strutturali eseguite su tre delle più importanti cupole dell’antichità, consentono valutazioni importanti sulle specifiche qualità che hanno consentito di interpretarne i dissesti giustificando le condizioni che hanno conservato fin ai tempi attuali
THE SOIL STIFFNESS INFLUENCE AND THE EARTHQUAKE EFFECTS ON THE COLOSSEUM IN ROMA
No full textQuesta pubblicazione attinge ai risultati conseguiti nell’ambito delle ricerche sul Colosseo esegute da Cerone e coll.;di particolare interesse è il confronto dei risultati delle analisi strutturali relative agli effetti indotti sulle strutture sia da assestamenti legati al suolo eterogeneo sia dalle azioni sismiche applicate con diversi orientamenti rispetto agli assi del monumento. Gli stati tensionali giustificano ampiamente l’evoluzione dei dissesti subiti nel corso dei secoli, individuando le zone che, per prime, sono state interessate dalle lesioni e dai crolli e dai successivi sviluppi
THE RE-FORMATION OF ARENA FLOOR DECK OF COLOSSEUM IN ROMA
No full textLe vicende che hanno accompagnato il Colosseo fino al raggiungimento dell’attuale conformazione mutila e dissestata, vengono interpretate alla luce della storia; non è escluso che i primi dissesti siano stati determinati da un effetto sinergico tra l’incendio del III secolo (proposto generalmente come causa diretta), l’assestamento della fondazione (prolungato nel tempo sotto la grande mole della costruzione) e i quasi contemporanei eventi sismici avvenuti. Questi furono di intensità modesta ma sufficiente per determinare il crollo lungo la cavea fino all’arena delle colonne dell’attico (ormai rese semplicemente appoggiate dopo la devastazione delle travi lignee del portico, bruciate nell’incendio), rovesciate dal terremoto. Le analisi strutturali eseguite suggeriscono questa possibilità
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