Reliability of simplified analytical models for the analysis of FRP reinforced masonry frames

The paper faces the problem of the evaluation of the increase of strength obtained by means of the FRP application at the intrados of a simple masonry structure, made by two piers and an arch, which can be considered the reference module of typical bridge structural schemes. In this framework a simplified analytical model able to estimate the failure domain of the FRP reinforced structure is validated through a comparison with the results of a non linear numerical model

Resistenza della parete esterna del Colosseo alle azioni sismiche

The strength of the external wall of the Colosseum under out warding horizontal forces is evaluated by means of non-linear pushover analyses. Many different loading directions are considered in order to define the worst load condition for the monument. The analysis takes into account the properties of the different materials of the structure: the travertine masonry blocks and the roman concrete. The failure domains of the materials are evaluated and the cracking spreading on the wall at increasing forces is defined by means of an iterative procedure which modifies the membrane stiffness of the finite elements according to the actual state of stress. The application of horizontal loads parallel to the minor axes of the elliptic plan of the monument for a peak acceleration of 0.13 shown that the vertical cracks extend up to the extrados of the circumferential arches of the third order a vertical portion of the external wall can overturn outwards. The peak normal acceleration which gives the overturning of a strip delimited by vertical cracks is about equal to 0.14g. Therefore this value can be considered the ultimate horizontal peak acceleration of the monument in the actual configuration. The comparison with the result obtained in Coccia and Ianniruberto (2004) show the great reduction of the lateral strength respect to the original configuration. This reduction is mainly due to the lack of the third and fourth order ambulatory vaults that increases the height of the unrestrained part of the external wall and its vulnerability to horizontal forces

Role or fiber reinforced plastic sheets in shear response of reinforced concrete beams: experimental and analytical results

The paper is principally aimed at analyzing the role of externally applied fiber reinforced plastic (FRP) sheets in the shear ultimate behavior of reinforced concrete elements. A theoretical model for predicting the shear resisting contribution of FRP sheets is illustrated. The proposal is based on a complete equilibrium/compatibility approach for reinforced concrete beams failing in shear and considers the possible interactions between the composite contribution and the resisting mechanisms of an ordinary reinforced concrete beam. The proposal is discussed and tested by means of an experimental investigation carried out on beams reinforced by glass FRP composite sheets with a shear span to depth ratio equal to 3. Further comparisons are then performed that consider the predictions of other existing approaches reported in the literature

Analisi della resistenza delle strutture del Colosseo sotto forze orizzontali

Scopo del lavoro è la valutazione delle massime azioni sismiche sopportabili dalla struttura della parete esterna del Colosseo nella configurazione attuale. L’analisi strutturale è basata su un modello non lineare che tiene conto della complessa geometria del monumento e delle diverse tipologie di sezioni resistenti all’azione orizzontale. La resistenza della struttura è individuata attraverso un’analisi statica incrementale ed è definita come il valore dell’accelerazione al piede che produce i primi crolli

Ultimate behavior of masonry arches reinforced with FRP at the intrados: comparison between analytical and numerical models

The application of FRP materials at the extrados or intrados of masonry arches sharply modifies the bearing capacity and the failure mode of the structures. In this case the classical limit analysis theory, suitable for the collapse behavior of un-reinforced masonry structure, cannot be applied due to the FRP presence, which prevents the formation of a mechanism. The evaluation of the ultimate behavior of reinforced arches with a suitable analytical model has been already proposed by the authors. Aim of the paper is a validation of this model by means of a numerical procedure developed with a FEM program, able to account for the presence of the composite material bonded at the surface. In particular in this paper the analyses will be devoted to the collapse response of masonry arches reinforced with FRP at the intrados and subjected to vertical loads. On the basis of the comparison with numerical outcomes the effectiveness of the analytical methodology in predicting the ultimate load and the failure mode is pointed out

Systems of arches and columns strengthened with FRP at the extrados

The topical problem of the maintenance and upgrading of the masonry building heritage has led, in these last years, to an increasing interest in new and suitable material and technologies. As a consequence the application of composite material, also on masonry structures, is nowadays considered an assessed and quite usual practice. Nevertheless the adoption of new techniques requires a deep knowledge of the behavior of the reinforced structure and a definition of adequate models able to simulate it. Aim of this paper is the evaluation of the structural behavior of a system of arch and columns, strengthened with FRP at the extrados and loaded by a vertical force at the crown and by two horizontal forces at the abutments of the arch. The scope is pursued by means of a proposed methodology, which, with some simplifying assumptions, allows defining the failure interaction locus of the strengthened structure. The effectiveness of the strengthening intervention is evaluated on the basis of these strength domains defined in the plane of loads

Analisi della resistenza della parete dell’attico del Colosseo nella sua configurazione originaria in presenza di forze orizzontali

In questo lavoro si studia la risposta strutturale dell’attico del Colosseo nella sua configurazione originaria in presenza di azioni orizzontali. L’analisi di tipo “push over” è condotta tenendo conto della presenza dei diversi materiali, la muratura in blocchi di travertino e il calcestruzzo romano, e delle loro proprietà costitutive. L’analisi mostra l’evoluzione del danneggiamento della struttura legato alla rottura di uno o entrambi i materiali fino al raggiungimento delle condizioni di ribaltamento di alcune isolate porzioni di struttura

Resistenza laterale di portali in muratura rinforzati con FRP all’intradosso

Il lavoro presenta un modello di calcolo di strutture elementari in muratura, costituite da due colonne e un arco circolare a tutto sesto, rinforzate con FRP all’intradosso. Il rinforzo si considera esteso a tutta la superficie interna della struttura e si suppone non ancorato alla base dei piedritti. I risultati mostrano l’efficacia di tale tecnica d’intervento nell’incrementare la resistenza della struttura e la sua dipendenza dai parametri geometrici e meccanici in gioc