Laura RAGNI

Pubblicazioni

Laura RAGNI

 

130 pubblicazioni classificate nel seguente modo:

Nr. doc. Classificazioni
89 4 Contributo in Atti di Convegno (Proceeding)
36 1 Contributo su Rivista
3 2 Contributo in Volume
2 5 Altro
Anno
Risorse
2008
Finite element formulation for geometric and material nonlinear analysis of beams prestressed with external slipping tendons
FINITE ELEMENTS IN ANALYSIS AND DESIGN
Autore/i: A., Dall'Asta; Ragni, Laura; A., Zona
Classificazione: 1 Contributo su Rivista
Abstract: In this paper a finite element formulation of a geometric and material nonlinear analytical model for externally prestressed beams is illustrated. Differently from existing methods starting from the linear theory and then including the tendon eccentricity variation,the analytical model adopted is based on a nonlinear kinematical theory. Thus a completed escription of the nonlinear interactions between tendon and beam is given. The interactions between axial and flexural fields of the beam are also included.The numerically simulated response is verified by comparison with experimental tests available for concrete beams and steel–concrete composite beams prestressed with external tendons.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/37871 Collegamento a IRIS

2007
Dynamic systems with high damping rubber: nonlinear behaviour and linear approximation
Proceedings of the 10th World Seminar on Seismic Isolation, Energy Dissipation and Active Vibration Control of Structures
Autore/i: A., Dallasta; Ragni, Laura
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/47193 Collegamento a IRIS

2007
Application of HDR devices for the seismic protection of steel-concrete composite frames: experimental result
Atti dell’A.N.I.D.I.S. 2007
Autore/i: Dall’Asta, A.; Dezi, Luigino; Giacchetti, R.; Leoni, G.; Ragni, Laura; Zito, L. F.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/72369 Collegamento a IRIS

2007
Criteri semplificati di progetto per strutture miste dotate di controventi dissipativi in gomma ad alto smorzamento
Materiali ed Approcci Innovativi per il Progetto in Zona Sismica e la Mitigazione della Vulnerabilità delle Strutture
Autore/i: Dall’Asta, A.; Dezi, Luigino; Leoni, G.; Ragni, Laura
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/72372 Collegamento a IRIS

2007
Steel-concrete composite frame equipped with high damping rubber devices and buckling restrained braces: experimental results
Atti del XXI Congresso C.T.A.
Autore/i: Carbonari, Sandro; Dall’Asta, A.; Dezi, Luigino; Leoni, G.; Ragni, Laura; Zito, L. F.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/72366 Collegamento a IRIS

2007
Un metodo semplificato per la valutazione della capacità portante di travi in c. a. precompresse con cavi esterni
Atti del 24° Convegno Nazionale A.I.C.A.P.
Autore/i: Dall'Asta, A.; Dezi, Luigino; Ragni, Laura; Zona, A.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/72364 Collegamento a IRIS

2007
Sistemi di dissipazione basati su gomme ad alto smorzamento: descrizione mediante modelli lineari equivalenti
Atti dell’A.N.I.D.I.S. 2007
Autore/i: Dall’Asta, A.; Ragni, Laura
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/72367 Collegamento a IRIS

2007
Simplified method for flexural failure analysis of steel-concrete composite beams post-tensioned with external tendons
Proceedings of the 3rd International Conference on Steel and Composite Structures
Autore/i: A., DALLASTA A; Ragni, Laura; A., Zona
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/46350 Collegamento a IRIS

2007
Analytical model for geometric and material nonlinear analysis of externally prestressed beams
JOURNAL OF ENGINEERING MECHANICS
Autore/i: A., Dall'Asta; Ragni, Laura; A., Zona
Classificazione: 1 Contributo su Rivista
Abstract: The analysis of beams prestressed by external slipping tendons involves various difficulties related to the coupling between the local strain of the tendons and the global deformation of the beam. The structural behavior of the beam–tendon system at collapse is ruled both by the nonlinearity of materials and by geometric nonlinear effects. Recent scientific papers have shown the relevance of the geometric effects in evaluating the failure load of externally prestressed beams by considering the tendon eccentricity variation. The change of eccentricity is however only one of the geometric nonlinear effects. In this work the writers present a complete geometric and mechanical nonlinear analytical model based on the theory of small strains and moderate rotations deduced from the finite deformation theory.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/37867 Collegamento a IRIS

2007
Simplified method for failure analysis of concrete beams prestressed with external tendons
JOURNAL OF STRUCTURAL ENGINEERING
Autore/i: A., Dall'Asta; Ragni, Laura; A., Zona
Classificazione: 1 Contributo su Rivista
Abstract: The flexural strength of externally prestressed beams depends on the tendon stress at failure. If the tendon is free to slip at the deviators its stress will depend on the global deformation of the whole structure. Thus the tendon stress at failure, and consequently, the flexural strength cannot be evaluated by a local analysis of the critical sections, but a nonlinear analysis of the whole beam-tendon structural system is required. In the past, simplified formulas were proposed to calculate the tendon stress increment at failure avoiding the need for a nonlinear analysis of the entire structure. Some of these formulas have been adopted as code recommendations. Some approaches however do not seem to be consistent with the actual behavior of externally prestressed beams and in some cases excessively high increments of stress are recommended. On the other hand, other approaches appear to be too conservative. In this work a new simplified and rational method of analysis based on shape functions approximating deformations is proposed to study the tendon stress increment and consequently the flexural strength of externally prestressed concrete beams. The proposed simplified method reduces the analysis of externally prestressed structures from a global structure problem to an easier section problem.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/37868 Collegamento a IRIS

2007
Application of HDR devices for the seismic protection of steel-concrete composite frames: experimental results
Proceedings of the 6th Int. Conf. on Steel and Aluminium Structures
Autore/i: Dall'Asta, A.; Leoni, G.; Carbonari, S.; Dezi, L.; Ragni, L.; Zito, L.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/52307 Collegamento a IRIS

2007
Application of HDR devices for the seismic protection of steel-concrete composite frames: experimental results
5th International Conference on Advances in Steel Structures, ICASS 2007; Singapore; Singapore; 5 December 2007 through 7 December 2007; Code 88969
Autore/i: Dall'Asta, A.; Leoni, G.; Carbonari, Sandro; Dezi, Luigino; Ragni, Laura; Zito, L.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/58501 Collegamento a IRIS

2006
Seismic design of composite frames endowed with HDR devices
Proceedings of the 5th International Conference on the Behaviour of Steel Structures in Seismic Areas
Autore/i: A., Dall'Asta; Dezi, Luigino; R., Giacchetti; G., Leoni; Ragni, Laura
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/51585 Collegamento a IRIS

2006
Application of HDR devices for the seismic protection of steel concrete composite frames: experimental results
Proceedings of the 5th International Conference on the Behaviour of Steel Structures in Seismic Areas
Autore/i: A., DALL'ASTA A; Dezi, Luigino; R., Giacchetti; G., Leoni; Ragni, Laura
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/52064 Collegamento a IRIS

2006
Un metodo semplificato per l'analisi a collasso di travi in calcestruzzo post tese con cavi esterni
Atti del 16° Congresso C.T.E.
Autore/i: Dall'Asta, A.; Dezi, Luigino; Ragni, Laura; Zona, A.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/72374 Collegamento a IRIS

2006
Experimental tests and analitycal model of high damping rubber dissipation devices
Nota Tecnica di Dipartimento n. 12
Autore/i: Dall’Asta, A.; Ragni, Laura
Luogo di pubblicazione: Department of Architecture, Construction and Structures, Università Politecnica delle Marche
Classificazione: 5 Altro
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/82249 Collegamento a IRIS

2006
Steel-concrete composite beams prestressed by external tendons: effects of material and geometric nonlinearities.
ADVANCED STEEL CONSTRUCTION
Autore/i: A., DALL'ASTA A; Ragni, Laura; A., Zona
Classificazione: 1 Contributo su Rivista
Abstract: The analysis of externally post-tensioned beams is characterized by some specific issues related to the coupling between the local strain of the cable and the global deformation of the structure. Collapse modalities are influenced by the nonlinear behavior of materials and in many cases by non-negligible geometric nonlinear effects. The authors present a model for externally prestressed steel-concrete composite beams that includes geometric and material nonlinearities. The proposed model is based on the theory of small strains and moderate rotations obtained from the exact nonlinear theory. Comparisons with experimental tests are shown to validate the results obtained with the proposed formulation. Some numerical applications involving simply supported and two-span continuous composite beams post-tensioned with external cables are discussed to illustrate the nonlinear geometric effects and their influence on the ultimate capacity.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/37866 Collegamento a IRIS

2006
Experimental tests and analytical model of High Damping Rubber dissipating devices
ENGINEERING STRUCTURES
Autore/i: A., Dall'Asta; Ragni, Laura
Classificazione: 1 Contributo su Rivista
Abstract: High damping rubber (HDR) consists of natural rubber to which black carbon filler is added to increase its damping properties. The use of HDR as a dissipating device in structural systems is very promising in terms of controlling the response under live actions like wind or earthquake. The use of HDR does however entail some problems because its dynamic behaviour is not completely understood and the few HDR models that exist are not completely satisfactory for seismic analysis of structures equipped with HDR-base dissipation devices. Experimental tests were performed to obtain more accurate information about the behaviour of the material under cyclic shear paths with different strain rate and strain amplitude. A nonlinear viscoelastic damage model was proposed to describe the behaviour of rubber under cyclic loads.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/37865 Collegamento a IRIS

2005
Cyclic behaviour of HDR dissipating devices: experimental tests and analytical model
9th world seminar on seismic isolation energy dissipation and active vibration control of structures
Autore/i: Dall'Asta, A; Dezi, Luigino; Giacchetti, R; Leoni, G.; Ragni, Laura
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/44695 Collegamento a IRIS

2005
Steel-concrete composite frames equipped with HDR based dissipation devices: experimental tests
Atti del XX Congresso C.T.A.
Autore/i: Dall’Asta, A.; Dezi, Luigino; Giacchetti, R.; Leoni, G.; Ragni, Laura
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/74242 Collegamento a IRIS

2005
Steel-concrete composite beams prestressed by external cables: effects at collapse of material and geometric nonlinearities
Proceedings of ICASS05 – Fourth International Conference on “Advances in Steel Structures” Proceedings of ICASS05 – Fourth International Conference on “Advances in Steel Structures”
Autore/i: Dall’Asta, A.; Ragni, Laura; Zona, A.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/82228 Collegamento a IRIS

2005
Dynamic response of composite frames with rubber-based dissipating devices: experimental tests
Proceedings of ICASS05 – Fourth International Conference on “Advances in Steel Structures”
Autore/i: A., Dall'Asta; Dezi, Luigino; R., Giacchetti; G., Leoni; Ragni, Laura
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/44975 Collegamento a IRIS

2005
Design of vibration control devices for a steel footbridge
Proceedings of the 2th International Conference "Footbridges 2005"
Autore/i: Dall'Asta, A.; Ragni, Laura
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/82229 Collegamento a IRIS

2005
A simplified method for evaluating the ultimate tendon force increment in externally prestressed steel-concrete composite beams
Atti del XX Congresso C.T.A.
Autore/i: Dall’Asta, A.; Zona, A.; Ragni, Laura
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/82231 Collegamento a IRIS

2004
Application of dissipating braces forthe earthquake protection of steel concrete composite structures
Atti del VI Workshop Italiano sulle Strutture Composte
Autore/i: Dall’Asta, A.; Dezi, Luigino; Giacchetti, R.; Leoni, G.; Ragni, Laura
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/74237 Collegamento a IRIS

2004
Externally prestressed steel-concrete composite beams: effects at collapse of material and geometric nonlinearities
Atti del "VI Workshop Italiano sulle Strutture Composte"
Autore/i: Dall’Asta, A.; Ragni, Laura; Zona, A.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/82232 Collegamento a IRIS

2004
Progetto del sistema di controllo delle vibrazioni di un ponte pedonale in acciaio.
Atti del II Workshop: Problemi di vibrazione nelle strutture civili e nelle costruzioni meccaniche
Autore/i: Dall’Asta, A.; Ragni, Laura
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/82233 Collegamento a IRIS

2004
Flexural strength of concrete bridges prestressed by external tendons
Proceedings of the fib Symposium on Segmental Construction in Concrete
Autore/i: Dall'Asta, A.; Ragni, Laura; Zona,
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/82230 Collegamento a IRIS

2003
Non linearità geometriche e meccaniche nell'analisi di travi composte presollecitate esternamente
Atti del XIX Congresso C.T.A.
Autore/i: Dall’Asta, A.; Ragni, Laura; Zona, A.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/82807 Collegamento a IRIS

2003
Ponte pedonale sul fiume Esino
Atti del XIX Congresso C.T.A.
Autore/i: Dall’Asta, A.; Ragni, Laura
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/82808 Collegamento a IRIS




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