1,721,184 research outputs found
Experimental Characterization and Numerical Investigation on the Azzone Visconti Bridge in Lecco (Italy)
Full text linkAbstractThe paper presents the results of a numerical investigation on the Azzone Visconti Bridge in Lecco (Italy). Starting from the historical data and from an extensive mechanical characterization of both the soil constituting the riverbed and of the masonry constituting the piers, the aim of the analyses is to predict the behaviour of the structure under the testing loading scheme prescribed by the current Italian Code. A finite element structural model has been conceived, and three different models describing the mechanical behaviour of the foundation have been implemented. Limited differences are observed in terms of absolute vertical settlement of the bridge, but important effects are highlighted in terms of stress redistribution within the piers
Numerical simulation of the shaking table test of a full scale, seven story shear wall specimen
No full textPressure–impulse diagrams for RC and FRC circular plates under blast loads
No full textIn this work, simplified models for the dynamic analysis of traditional reinforced concrete (RC) and fibre-reinforced concrete (FRC) circular plates under blast loads are proposed. The cases of plates simply supported or resting on Winkler-type soil are studied. The two cases under study intend to provide a simplified tool for predicting the response respectively for specimens subjected to blast pressure wave inside shock-tube facilities and for slabs on ground under blast loads. The second case also represents the loading conditions inside a new shock-tube facility specifically intended for the investigation of underground tunnel lining subjected to blast loads. The aim of this work is the pressure-impulse diagrams derivations for circular plates with several material characteristics, radius/thickness ratio and Winkler's constant
Pressure–impulse diagrams of RC beams considering fire–blast interaction
Full text linkWhen analyzing military, defense, or structures/infrastructures deemed critical, explosion-induced actions—often associated with malicious actions—play a significant role. The combined effect of a blast and fire is not uncommon: in fact, an explosion can be the extreme consequence of a fire or vice versa, a fire can occur as the result of an explosion. Although advanced numerical approaches can be a proper solution for analyzing critical structures and infrastructures subjected to accidental actions, their complexity makes these approaches unsuitable for the analysis of ordinary buildings or even for the preliminary design of structures. A pressure–impulse diagram is an easy and common tool that can be adopted to verify the safety of structural members for a wide range of blast scenarios even considering the damage caused by a previous fire. This study aims to compare different approaches that can be adopted for the construction of pressure–impulse diagrams of reinforced concrete structures subjected to a blast and a blast preceded by fire. Taking as a reference case a statically indeterminate beam with three supports, this work presents the influence of the methods of analysis on the safety level assessed through pressure–impulse diagrams
SULLA DETERMINAZIONE DEL COEFFICIENTE DI RIDISTRIBUZIONE STRUTTURALE KRd PER STRUTTURE IN CALCESTRUZZO FIBRORINFORZATO
No full textLe strutture in calcestruzzo fibrorinforzato sono penalizzate da un’elevata deviazione standard del materiale e mostrano spesso una capacità portante molto superiore a quella computabile a partire dai valori caratteristici identificati attraverso le prove di
caratterizzazione che si basano su provini di piccole dimensioni. Questo aspetto è enfatizzato qualora le strutture siano caratterizzate da un elevato grado di iperstaticità. La normativa Italiana e più recentemente il nuovo codice modello hanno introdotto un coefficiente (fattore di ridistribuzione strutturale, KRd) in grado di tener conto di una più limitata variabilità della resistenza meccanica, qualora associata ad un grande volume coinvolto nel processo fessurativo o in presenza di significativa ridistribuzione tensionale. In questi casi la risposta è controllata da una resistenza più prossima al valor medio che a quello caratteristico. Viene
introdotta una procedura numerica in grado di tener conto della reale eterogeneità delle caratteristiche meccaniche della struttura per
la valutazione del coefficiente di ridistribuzione strutturale. Come esempio applicativo si mostra il calcolo di una piastra su suolo elastico
An innovative passive control technique for industrial precast frames
No full textA feasibility study is presented on the extension to reinforced concrete (RC) precast industrial buildings of a passive control technique aiming to provide additional damping to the structure and previously proposed for RC and steel framed structures. This technique, based on the insertion of friction devices
in the region of beam-to-column connections, is particularly advantageous due to the reduced dimension and low cost of the devices adopted. In the case of precast buildings, it offers the additional advantage of providing ductility to the hinged connections. In this work a general criterion for the device calibration is proposed; the modeling strategy for the device within a well-known simulation platform is presented.
A prototype building is designed for a medium-to-high seismic risk and the device is fine-tuned for this particular building. The device efficiency in modifying favorably the structural behavior is analyzed by comparing the seismic response of the bare and redesigned frame to twelve accelerograms having a PGA
equal to the design value. A non-critical shear increase in the zones where the device is inserted is found, largely counteracted by the reduction in extreme values for top displacement, bending moment at the column base and amount of energy dissipated in the hysteresis of materials
Macro-scale modelling for the seismic analysis: a case study.
No full textThe performance and the possible improvements of an existing beam spread-plasticity model have been investigated in this work, focusing on the case study of a lightly reinforced shear wall. The experimental response of the CAMUS I wall, tested on a shaking table under a sequence of five accelerograms, has been assumed as a benchmark. The wall response is strongly influenced by two non linear phenomena, namely the strength reduction due to M-N interaction and the stiffness degradation produced by cyclic shear, here quite pronounced due to the small amount of transverse reinforcement. The reproduction of these phenomena have been tackled first of all through an accurate set-up of the numerical model. Secondly, without modifying the model formulation, the hysteretic relationship governing the behaviour of the plastic hinge regions has been upgraded to include both degraded unloading and pinching branches. The numerical results match satis-factorily the experimental data, confirming the model capability in the non linear dynamic analyses of the wall at study
L'effetto della modellazione nella predizione della risposta sismica della parete a taglio CAMUS I
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