0000000000229723
AUTHOR
L. Cavaleri
Experimental determination of viscous damper parameters in low velocity ranges
In the last decades many strategies for seismic vulnerability mitigation of structures have been developed through analytical studies and experimental tests. Among these, energy dissipation by external devices assumes a great relevance for the relative design simplicity, even if applied to complex structures, and the effectiveness in reducing seismic demand. In particular, the use of fluid viscous dampers represents a very attractive solution because of their velocity-dependent behaviour and relatively low costs. The application on structures requires specific study under seismic excitation and a particular care of structural details. In this context the use of proper constitutive models fo…
Stress-strain models for normal and high strength confined concrete: Test and comparison of literature models reliability in reproducing experimental results
SUMMARY: The adoption of proper constitutive laws for confined concrete is basic for seismic assessment of new and existing reinforced concrete civil structures. The deformation capacity of reinforced concrete (RC) columns subjected to axially centred and eccentric loads depends on the effectiveness confinement action. A proper assignment of the stressstrainlaws for concrete allows obtaining an adequate definition of the ductility of the crosssections and correctly identifying mechanical nonlinearities in computational models.Several studies concerning the behaviour of confined concrete have been carried out, highlighting the role of different geometrical and mechanical parameters to the ov…
Capacità in compressione di colonne in calcestruzzo confinato con FRP/Acciaio in presenza di precarico
Nell'ambito del recupero e rinforzo delle costruzioni esistenti, il confinamento di colonne in calcestruzzo armato con materiali polimerici fibro-rinforzati (FRP) e la tecnica di incamiciatura tramite il sistema combinato di angolari e piatti in acciaio (Steel Jacketing) risultano molto utilizzate, in quanto offrono notevoli vantaggi in termini di incremento della capacità portante e deformativa agli elementi strutturali che presentano carenze di requisiti sismici. L'esecuzione dell'intervento di rinforzo in condizioni di esercizio della struttura implica la presenza di uno stato tenso-deformativo esistente nelle colonne, causato dalla presenza dei carichi gravitazionali. Questo può comport…
A semi-empirical stress-strain model for equivalent strut fiber-section modeling of infilled frames
Infill-frame interaction is commonly modeled by means of equivalent strut macro-models. The main difficulty in using this phenomenological approach is to properly calibrate a force-displacement curve for the struts, as this depends not only on the geometrical and mechanical properties, but more specifically on the different potential damage mechanisms which may occur for the infill-frame system subject to lateral forces. If fiber-section elements are used as diagonal struts, the force-displacement curve is substituted by a stress-strain law. In both cases, the attribution of the inelastic law of the struts, based on a mechanical approaches, is not valid in general, as mechanical approaches …
MODELLING IN-PLANE AND OUT-OF-PLANE RESPONSE OF INFILLED FRAMES THROUGH A FIBER MACRO-MODEL
A new fiber macro-model for the simulation of combined in-plane and out-of plane response of infilled frames subjected to seismic actions is presented in the paper. The model consists of 4 pinned struts (two diagonals, one horizontal and one vertical) modeled with the nonlinear beam/column fiber-section elements available in OpenSees. The model is particularly suitable to predict the out-of-plane response as fiber-section elements can account for the coupling between axial load and bending moment occurring because of the arching mechanism developed by the infills beyond the first cracking. Moreover the model can account for the effect of the reciprocal damaging accumulated both in-plane and…
Assessment of the load carrying capacity of reinforced concrete columns strengthened by steel cages Specificità nella valutazione della capacità portante di colonne in calcestruzzo armato rinforzate con incamiciatura in acciaio
In the present paper, a selected review of the most relevant analytical models provided for the evaluation of the con-finement properties of Steel Jacketed RC columns is discussed. The reliability of the models is tested by comparing the analytical predictions of the load capacity with experimental results available in the literature depending on the type of mechanical end-connections. Moreover, new considerations regarding the application of the steel jacketing on columns while loaded are faced by experimental investigation
COMPRESSIVE BEHAVIOR OF CONCRETE COLUMNS AXIALLYLOADED BEFORE CFRP-WRAPPING. REMARKS BY EXPERIMENTALNUMERICAL INVESTIGATION
Strengthening of existing concrete columns with Fiber Reinforced Polymers (FRP) results generally in a satisfactory structural member improvement in terms of load and strain capacity. A reliable prediction of the capacity obtained by these reinforcement strategies requests a proper knowledge of the load-strain response of the confined concrete elements. However, so far, the available design methods and technical codes do not consider the effect of the possible presence of service loads at the moment of application of the reinforcement, and therefore, the compressive behavior of the concrete confined under preload is still unclear. In this paper, the effect of sustained loads on the compress…