1,720,981 research outputs found
Modelling of the in-plane behaviour of masonry walls strengthened with polymeric grids embedded in cementitious mortar layers
No full textThe seismic reinforcement of masonry walls needs to be carried out through appropriate and effective techniques aiming at providing both adequate strength and displacement capacity. The present research concerns experimental results about the in-plane behaviour of masonry walls strengthened through an innovative technique employing polymeric grids embedded in cementitious mortar layers applied on the wall surface. The behaviour of strengthened masonry walls subjected to cyclic shear-compression tests is examined in order to quantify the strength and displacement capacity increment provided by the reinforcement. A Finite Element Model of the unreinforced and reinforced panels has been developed and parameters defining masonry and strengthening materials have been calibrated by means of comparisons with the experimental results. The effectiveness of the strengthening system has been then numerically investigated through a wide parametric analysis varying the masonry strength, the wall shape, the axial stiffness of the strengthening grid and the strength of the mortar. Finally, a comparison of the effectiveness of the polymeric grid with a traditional steel one embedded in the same mortar layer is also reported
Modelling of the bond behaviour of tuff elements externally bonded with FRP sheets
No full textThe performance of fibre reinforced plastic (FRP) materials used for external strengthening depends strongly on the bond behaviour at the FRP-substrate interface. In this paper, the results of an analytical model and of two Finite Element (FE) models (bi-and three-dimensional) for simulating bond behaviour in FRP-strengthened masonry elements using zero-thickness interface elements are presented. The primary parameters of bilinear and nonlinear bond-slip laws were determined from experimental results of single shear bond tests that the authors conducted on masonry blocks of yellow tuff bonded with FRP carbon and glass fabrics. Several parametric analyses were conducted to estimate the effect of the primary bond law parameters on the global behaviour of the specimens and to determine the effective bonded length for the investigated masonry support
Bond tests on tuff elements externally bonded with FRP materials
No full textThe experimental results of several bond tests on masonry blocks made of yellow tuff and
bonded with different types of Fibre Reinforced Plastic (FRP) fabrics carried out by the authors are
presented and analysed. The discussion of results is mainly focused on: (1) assessing the set-up reliability,
(2) choosing sufficient bonded length for achieving the full bond strength, (3) estimating the efficacy of end
anchoring systems, (4) evaluating the effect of a plastering layer and of the masonry strength on the
debonding load. The results are analysed both in terms of global (failure modes and loads, load–displacement
curves) and local behaviour (distribution of axial strains and shear stresses) aimed to evidence the
different behaviour of the used fibres (carbon, glass, basalt, flax). Finally, the experimental failure loads are
compared with formulations based on a ‘design by testing’ approach
Evaluation of the natural vibration frequencies of a historical masonry building accounting for SSI
No full textThe dynamic identification of a historical masonry palace located in Benevento (Italy) has been carried out. The case study is representative of many buildings located in historic Italian centres. Since the building has been instrumented by the Department of Civil Protection with a permanent dynamic monitoring system, some of the recorded data, acquired in various operating conditions have been analysed with basic instruments of the Operational Modal Analysis in order to identify the main eingenfrequencies and vibration modes of the structure. The experimental results have been compared to the numerical outcomes provided by a detailed three-dimensional Finite Element (FE) model of the building where Soil–Structure Interaction (SSI) has been taken into account. The comparison of experimental vs. numerical frequencies and vibration modes of the palace evidenced the role exerted by the subsoil on the dynamic response of the building
SSI on the Dynamic Behaviour of a Historical Masonry Building: Experimental versus Numerical Results
No full textA reliable procedure to identify the dynamic behaviour of existing masonry buildings is described in the paper, referring to a representative case study: a historical masonry palace located in Benevento (Italy). Since the building has been equipped with a permanent dynamic monitoring system by the Department of Civil Protection, some of the recorded data, acquired in various operating conditions, have been analysed with basic instruments of the Operational Modal Analysis in order to identify the main eigenfrequencies and vibration modes of the structure. The obtained experimental results have been compared to the numerical outcomes provided by three detailed Finite Element (FE) models of the building. The influence of Soil-Structure Interaction (SSI) has been also introduced in the FE model by a sub-structure approach where concentrated springs were placed at the base of the building to simulate the effect of soil and foundation on the global dynamic behaviour of the structure. The obtained results evidence that subsoil cannot a priori be disregarded in identifying the dynamic response of the building
Effect of the Presence of Mortar Joints in the Bond Behaviour of Tuff Masonry Elements
No full textIn this paper, the bond behaviour of masonry elements made of tuff stone and bonded with different types of FRP fabrics (glass, carbon, basalt) has been investigated through an experimental campaign. Tuff is a natural stone representing a very common base material for the construction of masonry buildings in Southern Italy and many Mediterranean areas. Two series of specimens have been tested: 1) single blocks and 2) prisms made of three blocks and two mortar joints. The tests have been carried out according to a single-lap shear scheme according to a push-pull set-up. Presence of a plastering was also investigated for both series. The experimental results have been examined in terms of both debonding load and local stress transfer phenomena in order to evidence the performance of the different fibres and the effect of both mortar joints and plastering
Structural behaviour of masonry walls stregthened with mortar layers reinforced with FRP grids
No full textThe seismic events recently occurred all over the world and, in particular, in Europe have shown the high vulnerability of particular classes of buildings against the horizontal actions. The damage of structural masonry walls is one of the most widespread harming injuries and cause of loss
of serviceability and seismic capacity for a building. The damage experienced by these masonry elements has brought to light the necessity to strengthen them with appropriate reinforcing systems in
order to achieve an upgrading to the necessary seismic and energy dissipation capacity. Different strengthening systems have been proposed and studied during the last decades, with particular
reference to the type of materials, system configuration with respect to the element to be strengthened, difficulties in the application and effectiveness of the reinforcement. Even though in the
last years different studies have been carried out in this field, many issues regarding the methods for
the evaluation of the actual behaviour of these techniques, and their effectiveness in the improvement of seismic behaviour of structural members to which they are applied, are still open.
In the present study the structural behaviour of unreinforced masonry walls strengthened with composite grid reinforced mortar layers is studied. The characterization of the reinforcing system and the assessment of the overall increase of capacity of the strengthened masonry walls is performed.
First of all, the study is focused on the investigation of the mechanical characteristics of the strengthening system in itself. In fact, the structural behaviour of an externally applied strengthening
system for masonry walls is examined. The reinforcing technique considered in the present research is composed by mortar layers incorporating a FRP reinforcement in form of grid. The FRP reinforced mortar layers are externally applied to the wall surfaces in a symmetric fashion, and can also be connected to the wall by means of an adequate connection system. The mechanical behaviour of the reinforced mortar under tensile, compression and shear loading is assessed through laboratory tests
and constitutive laws can be proposed to characterize the reinforced mortar mechanical behaviour.
The experimental characterization of the presented system is followed by and validated through numerical modelling and simulation of its mechanical behaviour.
In a second phase, the behaviour of masonry walls strengthened by means of the considered
technique is studied. The in-plane shear behaviour is considered, in case of cyclic loading state. The performances of the global strengthened assemblage is thus examined with both experimental and
numerical investigation criteria. Also, the overall ductility and energy dissipation capacity of the system, while subjected to horizontal in-plane actions, is studied. The actual mechanical behaviour of the proposed structural solution is investigated through an experimental program with prototypes.
Furthermore, a finite element model is realized in order to replicate the structural features of the strengthened masonry wall. The finite element model can be also used for further validation of the
panels performances
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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