1,721,137 research outputs found
Soil-structure interaction effects on the seismic response of multi-span viaducts
Full text linkThe paper focuses on the effects of soil-structure interaction in the seismic response of multi-span viaducts on pile foundations. Analyses are performed by means of the substructure approach: the soil-foundation systems are studied in the frequency domain to obtain the foundation input motion and the dynamic impedance functions; inertial interaction analyses are carried out in the time domain accounting for the material nonlinear behaviour.
Suitable lumped parameter models are introduced to simulate the frequency dependent behaviour of the soilfoundation system. A specific procedure for selecting and scaling real ground motions is proposed and used for the definition of the spatial seismic input. The seismic response of bridges on compliant base is compared with that obtained from fixed base analyses discussing the significance of soil-structure interaction effects
Field Tests on Micropiles Under Dynamic Lateral Loading
No full textAbstractMicropiles are increasingly used as foundation support of new buildings in seismic areas as well as for the seismic retrofitting of structures that have experienced seismic damage. Hence, it is essential to enhance the knowledge of the dynamic behavior of micropiles under horizontal loading. In the present paper, first steps of an extensive experimental study carried out on two vertical micropiles in alluvial silty soil are reported. One of the vertical micropiles is injected throughout valves a-manchèttes placed along the steel core of the shaft, while the other one is simply grouted. In particular, experimental results of ambient vibration tests and impact load tests are reported and a comparison between the behavior of the vertical injected and non-injected micropiles is provided. Experimental data of impact load tests are also compared with results obtained from an analytical model
Risposta Sismica di Pile da Ponte Fondate su Gruppi di Pali Inclinati.
No full textQuesto lavoro indaga la risposta sismica di pile da ponte fondate su gruppi di pali inclinati tenendo conto dell’interazione terreno-struttura e considerando gruppi di pali con differente geometria e diverse inclinazione dei pali. Le analisi di interazione sono eseguite ricorrendo al metodo per sottostrutture ed utilizzando, per le analisi di interazione cinematica delle palificate a pali inclinati, un modello numerico 3D agli elementi finiti sviluppato dagli autori in cui la non linearità del terreno è tenuta in conto con un modello lineare equivalente. I risultati delle analisi permettono di esprimere delle prime considerazioni circa l'influenza della configurazione della palificata e dell'inclinazione dei pali sul comportamento strutturale delle pile sulla risposta delle fondazioni
Dynamic analysis of inclined piles
No full textThe paper presents a numerical model for the kinematic interaction analysis of inclined pile groups; piles are modelled with beam finite elements and the soil is schematized with independent horizontal infinite layers. The pile-soil-pile interaction and the radiation problem are accounted for by means of elastodynamic Green’s functions. Piles cap is considered by introducing a rigid constraint; the condensation of the problem permits a consistent and straightforward derivation of both the impedance functions and the foundation input motions, which are necessary to perform the inertial soil-structure interaction analyses, according to the substructure approach. The model, which also allows evaluating the kinematic stress resultants in piles resulting from the propagation of seismic waves in the soil, is validated performing accuracy analyses and comparing results, in terms of dynamic impedance functions, kinematic response parameters and pile stress resultants, with those furnished by 3D refined finite element models
A numerical model for the dynamic analysis of inclined pile groups
No full textThe paper presents a numerical model for the dynamic analysis of pile groups with inclined piles in horizontally layered soil deposits. Piles are modelled with Euler-Bernoulli beams, while the soil is supposed to be constituted by independent infinite viscoelastic horizontal layers. The pile-soil-pile interaction as well as the hysteretic and geometric damping is taken into account by means of two-dimensional elastodynamic Green's functions. Piles cap is considered by introducing a rigid constraint; the condensation of the problem permits a consistent derivation of both the dynamic impedance matrix of the soil-foundation system and the foundation input motion. These quantities are those used to perform inertial soil-structure interaction analyses in the framework of the substructure approach. Furthermore, the model allows evaluating the kinematic stress resultants in piles resulting from waves propagating in the soil deposit, taking into account the pile-soil-pile interactions. The model validation is carried out by performing accuracy analyses and comparing results in terms of dynamic impedance functions, kinematic response parameters and pile stress resultants, with those furnished by 3D refined finite element models. To this purpose, classical elastodynamic solutions are adopted to define the soil-pile interaction problem. The model results in low computational demands without significant loss of precision, compared with more rigorous approaches or refined finite element model
Dynamic analysis of battered pile groups
No full textThe paper presents a numerical model for the kinematic interaction analysis of inclined pile groups; piles are modelled with beam finite elements and the soil is schematized with independent horizontal infinite layers. The pile-soil-pile interaction and the radiation problem are accounted for by means of elastodynamic Green’s functions. A rigid constraint is introduced to account for the pile cap and the problem condensation allows obtaining the dynamic impedance matrix of the soil-foundation system The model is validated comparing results, in terms of dynamic impedances, with those furnished by 3D refined finite element models
Dynamic Analysis of Inclined Piles
No full textThe paper presents a numerical model for the kinematic interaction analysis of inclined pile groups; piles are modelled with beam finite elements and the soil is schematized with independent horizontal infinite layers. The pile-soil-pile interaction and the radiation problem are accounted for by means of elastodynamic Green’s functions. Piles cap is considered by introducing a rigid constraint; the condensation of the problem permits a consistent and straightforward derivation of both the impedance functions and the foundation input motions, which are necessary to perform the inertial soil-structure interaction analyses, according to the substructure approach. The model, which also allows evaluating the kinematic stress resultants in piles resulting from the propagation of seismic waves in the soil, is validated performing accuracy analyses and comparing results, in terms of dynamic impedance functions, kinematic response parameters and pile stress resultants, with those furnished by 3D refined finite element models
Experimental modal analysis and finite element model updating of a historical masonry arch bridge
Full text linkThis paper presents the experimental test campaign to calibrate a finite element model intend-ed to evaluate the seismic vulnerability of the SS Filippo e Giacomo historical masonry arch bridge in Ascoli Piceno (Italy). The bridge has undergone very complex vicissitudes related mainly to exceptional river floods; it was partially rebuilt twice and other strengthening works were carried out over the time. The bridge, which is almost completely built with travertine blocks, has a total length of 146 m and follows a slightly curved path. Six arches, the main of which is semi-circular with span of 25 m and the others are lancet arches with span of about 8 m, support the carriageway that is about 8 m wide. The piers and abutments are founded on the bedrock and consequently some piers are deeply embedded in the sandy gravel deposit. A campaign of experimental tests was executed encompassing onsite measurements of stresses and modulus of elasticity, as well as laboratory measurements on specimens taken from the structures. Vibration tests were also carried out to evaluate the modal properties of the bridge. The acquired experimental data were used to calibrate a 3D Finite Element Model that has been developed considering the complex geometry of the bridge also including the deformable soil deposit. A very good consistency was achieved between experimental and theoretical be-haviours
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