1,721,859 research outputs found
The pure sliding collapse mode of non-symmetric masonry arches: a critical review of Monasterio's contribution and an alternative formulation
Full text linkAim of the present paper is to analyze and revisit the first chapter of the Monasterio’s unpublished manuscript where the pure sliding collapse mode of non-symmetric masonry arches is investigated. As it will be shown, the Monasterio approach is of a “kinematical” type, since the collapse mechanisms are “a priori” selected and, then, some criterion is adopted to identify the collapse condition. In the present study, it will be shown that the basic assumptions of the Monasterio’s analysis are fully in agreement with the modern limit analysis. Furthermore, an alternative formulation for the assessment of the equilibrium of non-symmetric arches is given
MICROMECHANICAL ANALYSIS OF UNREINFORCED AND REINFORCED MASONRY ARCHES
No full textThis work analyzes the in-plane response of unreinforced and reinforced masonry
arches by adopting micromechanical finite element (FE) models. These allow to describe onset
and evolution of degrading mechanisms until failure, including the accurate characterization
of the pre- and post-peak behavior. Two different models are adopted: the first considers each
masonry component, brick and mortar, as continuous material discretized with quadrilateral
FEs; the second connects properly resized bricks through interfaces representing both mortar
and mortar-units interaction. Linear elastic behavior is assumed for bricks, whereas a cou-
pled damage-friction constitutive law is adopted for mortar to account for typical arch collapse
mechanisms involving flexural hinges and shear sliding. As concerns the modeling of the rein-
forcements, these are considered as truss elements with bilinear response in tension. In such a
way the debonding and delamination phenomena are accounted in a simplified way.
Results obtained with the proposed models are validated through comparison with exper-
imental data and solutions obtained from other numerical approaches. It emerges that the
response of both the unreinforced and reinforced elements are satisfactorily described, as well
as the positive effect of the introduction of the reinforcement on the collapse load and failure
mechanism
Kinematic Stress Resultants in Inclined Single Piles Subjected to Propagating Seismic Waves: an Analytical Formulation
No full textThis paper presents an analytical model, based on the beam-on-dynamic Winkler foundation approach, for the evaluation of the kinematic stress resultants in single inclined piles subjected to the propagation of seismic waves. The Euler-Bernoulli beam model is adopted for the pile whereas analytical solutions available in literature for viscoelastic layers undergoing harmonic vibrations of a rigid disk are used for the soil. The coupled flexural and axial behaviour of the pile is governed by a system of partial differential equations, with the relevant boundary condi-tions, that is solved analytically in terms of exponential matrices. The solution for piles embed-ded in a homogeneous soil deposit is presented. Some applications, including comparisons of results with those obtained from rigorous boundary element formulations, demonstrate that the model, characterised by a very low computational effort, is able to accurately predict stress re-sultants in inclined piles subjected to seismic loading
DESIGN FOR ROBUSTNESS OF A PILOT BUILDING EQUIPPED WITH DISSIPATIVE FREE FROM DAMAGE STEEL CONNECTIONS
No full textRecent research initiative aimed at reducing the structural damage and its inherent economic consequences in steel and steel-concrete composite structures after severe earthquakes led to the development of FREE from DAMage (FREEDAM) beam-to-column connections. The practical applicability and the benefits of using these connections for structures in seismic areas are currently demonstrated within an ongoing RFCS pilot project to be built on the campus of the University of Salerno. Amongst the different structural requirements, Euro-codes nowadays require providing the structures with an appropriate robustness when subjected to identified or unidentified accidental events by ensuring that the undergone damages are not disproportionate to the initiating cause. This paper presents the design for robustness of the pilot building. The results indicate that the loss of a column at the base floor induces the development of significant catenary action in the beams bridging over the lost column. The structural performance under the column loss scenario is primarily governed by the behaviour of beam-to-column joints subsequently identified as critical zones. The full-range behaviour of the FREEDAM joints was investigated through complex numerical simulations which allowed validating a simplified component-based spring model that can be adopted for the regular design of structures adopting this joint typology
Struct-Stainability assessment of the Columna Capreoli A-Trusses of the San Lorenzo ad septimum monastery aula magna
No full textOriginal methodologies are proposed for formulating and solving optimization design problems concerned with the hazard assessment of a hypothetical solid wood replacement of the restored columna-capreoli A-trusses of the Aula Magna “Alfonso Gambardella” of the ancient monastery complex of San Lorenzo ad Septimum in Aversa, currently hosting the Department of Architecture and Industrial Design of the University of Campania “Luigi Vanvitelli”. The study addresses a twofold struct-stainability performance evaluation contemplating both the structural hazard originated from natural combined gravitational and dynamic actions, and the demand related to dynamics of anthropic/anthropogenic ecosystem consumption/transformation, in a scenario of short wood supply chain within the Piana Campana area. Both the contemplated hazard scenarios appear meaningful since: 1) the complex has suffered significant earthquake damage between 1456-1457, and 2) dedicated environmental studies by ISPRA/ARPAC elucidate a worrying condition of very high fragility for most of the lake, river and coastal ecosystems of the Piana Campana as well as an ‘endemic’ fragility condition for most of its territory. Encompassing both hazard perspectives, the optimization problems considered herein address the optimal choice between open- and closed-node solutions for the kingpost-strut A-trusses of the installation. Performance analyses have been carried out with the aid of an object-oriented in-house-developed multipurpose structural analysis code (MORES), employing finite-element formulations with a transversely isotropic structural model for wood based on a polytope strength criterion which has been calibrated from data made available from the military aeronautic industry and which has been suitably experimentally and numerically validated
Experimental and numerical investigation of a reinforced concrete building designed for gravity loads only
No full text
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
High performance computing applied to the seismic finite element analysis of an historic structure: the Temple of Athena in Paestum
Full text linkHistorical masonry structures constitute an extremely varied and complex set as far as building techniques. The analyses of their structural behaviour, when excited by a seismic event, are often affected by considerable uncertainty arising from the hypothetical definition of the mechanical properties of materials and of the constraint conditions between the elements.
The mechanical modelling of a historic building requires a knowledge of the properties of the various elements that make up the masonry and of the role they play: the masonry material, its use in the various components and, finally, how the connection between different elements are made in order to construct the building. The results of the work of modelling and the results of static and dynamic (seismic) analysis of the Temple of Athena, part of the broader site of monumental historical buildings in the Plain of Paestum, are presented in this paper.
This work is part of the research project "Costruito", carried out within the Istituto di Cibernetica "E. Caianiello" in Naples, which has, among its objectives, the purpose to define the main phases of the procedure that, starting from the identification of a historical building, ends with the determination of its structural behaviour in static and seismic phases.
The entire structure of the Temple of Athena has been modelled through a micro-modelling strategy in order to reproduce as faithfully as possible the whole geometry of the building. This approach has the disadvantage of being computationally expensive, given the large number of finite elements to be generated, but at the same time the merit of allowing, at a later stage, a more thorough validation and verification.
To face the high computational cost, particular attention was paid to the continuous verification in the modelling phase, through an accurate test quality of the meshed finite elements. The control of the characteristic length of each element has allowed a lower limit to the size of time step to be established and to contain within certain limits the duration of simulations.
With respect to this objective it has proved successful the choice of the modelling and pre-processing software, Hypermesh, that provides advanced features for the meshing procedure together with many effective testing tools.
The solver adopted for the simulation phase is Radioss, whose characteristics are well fit for the modelling of the contacts between surfaces (penalty based methods for the contact). A parallel version of this software (four CPUs) was used for the simulation on a vector parallel machine NEC Sx-8.
The results of simulation tests regarding static and seismic analysis are finally presented
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