This paper is available in Italian only.
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Comportamento in compressione di elementi in calcestruzzo rinforzati con angolari e piatti metallici
An analytical model for the determination of the compressive response of R.C. members having square transverse cross-section and reinforced with steel angels at the corners and steel plates connecting the steel angles is presented. The model is able to consider the contribution in confinement due to transverse and steel angles including buckling phenomena for steel angles was compared with experimental data available and with those obtained by using the other models available in the literature. Finally, a comment on the design prescriptions given by European and National codes in relation with the results here obtained is made.
This paper is available in Italian only.
Tecniche di valutazione del rischio sismico dei complessi ospedalieri
Seismic risk assessment of existing buildings is a very complex topic for researchers and engineers. Seismic evaluation of hospitals is quite more difficult, because of structurals, functionals, and equipments complexity. The paper, after a overview on current practice in this field, will finally present a case study, the hospital of Arzignano (Vicenza, Italy). Not only the structural safety, but also the assessment of non structural building elements are discussed.
This paper is available in Italian only.
Tubazioni interrate in zona sismica
Principles and application rules for the seismic design of the structural aspects of facilities composed of buried pipeline systems are discussed. Reference document is Part 4 of Eurocode 8, section 6: Specific principles and application rules for buried pipelines. Earthquake effects are represented in two different scenarios: a) seismic waves propagating on firm ground and producing different ground shaking intensity at distinct points on the surface and spatial soil deformation patterns within the soil medium; b) permanent deformations induced by earthquakes such as seismic fault displacements, landslides, ground displacements induced by liquefaction. The first scenario is proved to be non significant, in general, if the seismic wave propagation is accounted for in agreement to EC8, Part 4. According to EC8, Part 5, the basic model for pseudo-static analysis shall consist of the tube as a retaining structure of a soil wedge over the structure, supposed to be in a state of active limit equilibrium, of any surcharge loading acting on the soil wedge, and, possibly, of a soil mass at the foot of the wall, supposed to be in a state of passive equilibrium. To produce an active soil state, a sufficient amount of wall movement is necessary to occur during the design earthquake which can be made possible for a flexible structure. Different situations are envisaged depending on the shape of the tube, i.e. if it is a box type, of a rectangular cross section, or it is one of circular cross section.
This paper is available in Italian only.
Controventi innovativi del tipo «RSS»: regole di progetto ed affidabilità sismica
In this paper, a new design methodology for concentrically braced frames is presented aiming at the control of the failure mode by means of a rigorous application of the capacity design principles. The design goal is the prevention of the out-of-plan buckling of columns. In fact, the use of the recommendations provided by Eurocode 8 /1/, which have been substantially adopted by OPCM 3431 /2/, leads to the design of structures which are not able to exploit all the possible dissipative zones due to the premature out-of-plan buckling of columns. Whith reference to three bay concentrically braced frames having only one brace element for each braced bay, the proposed design methodology is applied both including and without including the local weakening strategy (Reduced Section Solution or RSS). The behaviour of concentrically braced frames designed according to above methodologies is compared with the one resulting from application of Eurocode 8 design rules. To this scope, the Jalayer and Cornell approach leading to the evaluation of the mean annual frequency of exceeding a given limit state is applied, so that the obtained results accounts for the record-to-record variability.
This paper is available in Italian only.
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Un criterio per l’ottimizzazione vincolata dei Liquid Column Mass Dampers (LCMD) per la mitigazione degli effetti sismici sulle strutture
Liquid Column Mass Damper (LCMD) devices offer an interesting solution to the problem of controlling structural vibrations. Even though a LCMD is less efficient than other passive systems, such as a Tuned Mass Damper (TMD), it is an extremely simple device, easy to install and economical. This paper presents a criterion aimed at optimizing the project parameters of the device. Unlike previous approaches proposed in literature, this criterion considers not only tre structural performance but also the simultaneous control of a constrained system of hydraulic protection. This means imposing that the best solution guaratees the maximum oscillation of the verti- cal liquid column without exceeding the column’s own stationary piezometric level in order to avoid jeopardizing the entire system by allowing air to enter the horizontal pipe section. The procedure is developed stochastically with the assumption that the seismic excitation is based on the Kanai Tajimi (KT) model of a white or coloured Gaussian stationary process. The structure to be protected is represented as a linear system with a single degree of freedom. The efficiency of the system of protection is evaluated by measuring the reduction of the horizontal movement caused at the base by seismic excitation. The solution, in statistical terms, regarding the non linear terms of the problem due to the loss of fluid viscosity in the pipe is evaluated by classical covariant analysis using the stochastic equivalent linearization technique. The matrix covariance elements, evaluated in the state space, are used both for the objective function (OF) and the constrained optimal solution to the problem which is represented by the maximum value of the vertical oscillation of the water column. The project vector used includes the hydraulic loss factor and the LCMD hydraulic frequency. A genetic hybrid algorithm is applied to obtain the desired effect of constrained optimal solutions independently from seismic intensity variations and some system parameters. An efficiency evaluation follows regarding the optimal project parameters for different conditions of operation.
This paper is available in Italian only.
Lo studio di interventi antisismici tramite analisi dinamiche con un modello ad elementi rigidi: il caso del Castello Maniace
A specific numerical model is proposed for the in-plane dynamical analysis of a masonry monument, with particular attention to the design of interventions for seismic protection. In order to perform effective compu- tational analyses, the present model is conceived to operate at the macro-scale considering the energy dissipation capacity of the masonry material, as well as the effects of the masonry texture on the local damage mechanisms. In particular, the model was implemented according with a mechanistic point of view, in the spirit of the rigid body and spring model approach, RBSM. In the present application we describe the passage from the global three dimensional model of the Maniace Castle in Syracusae to the identification of the specific collapse mechanism that is more at risk, and that can be specifically described by means of a plane model. Then, the dynamics of a transversal cross-section of the hypostyle salon of the Castle is investigated with particular attention to the enhancement of the seismic response that can be achieved by an intervention of rebuilding and reshaping of the buttresses.
This paper is available in Italian only.
Analisi statica non lineare di edifici in muratura esistenti mediante modelli strut and tie
A strut and tie model for not reinforced and not confined masonry panel is defined. This model permits to estimate the behaviour of the wall both in the linear elastic field and after the peak load, that is in the cracked non linear field up to the mechanism state. This model constitutes the base of non-linear static analysis method for existing masonry buildings that can be utilized into the practice.
This paper is available in Italian only.
La risposta fuori piano di sistemi murari: progetto e valutazione sperimentale di assorbitori di energia
The paper presents the results of shaking table tests carried out on masonry systems (scaled 1:1) strengthened by energy absorption devices designed to improve the out of plane response. Outcomes are fairly satisfactory, with reference to available ductility and damage control provided by the selected devices
This paper is available in Italian only.