366 research outputs found

    Can a professional development workshop with follow-up alter practitioner behaviour and outcomes for neck pain patients? A randomised controlled trial

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    Background: Continuing professional development (CPD) is a fundamental component of physiotherapy practice. Follow-up sessions provide opportunity for the refinement of skills developed during CPD workshops. However, it is necessary to identify if such opportunity translates to improved physiotherapist performance and patient outcomes

    A PROCEDURE FOR THE PROBABILISTIC ASSESSMENT OF MASONRY STRUCTURES UNDER TSUNAMI

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    Assessment of Tsunami vulnerability of coastal buildings has gained high interest in the last years for the areas characterized by a high Tsunami hazard. A probabilistic representation of vulnerability is performed by fragility curves, fundamental tools to define possible strategies for risk mitigation. Different prediction approaches can be used for obtaining analytical fragility curves. In this paper, a prediction proposal to be used for masonry structures typical of the Mediterranean coasts based on simplified structural analyses and damage indexes is presented. Different damage states are considered and inundation depth is assumed as input intensity measure. The uncertainties in the demand by the definition of the probability distribution of the inundation scenarios are considered. Further, the uncertainties in the structural capacity are included. Monte Carlo simulations are performed for the scope of this work

    Seismic analysis and risk mitigation of existing constructions

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    Following a thorough and lengthy procedure, we would like to thank all contributors for their highest calibre papers, which comprise the Special Issue on \u201cSeismic analysis and risk mitigation of existing constructions\u201d of the Open Construction and Building Technology Journal. The topic of the Special Issue encompasses a large number of issues spanning the design of special interventions for the reduction of the effects of earthquakes on civil structures and infrastructures, to the structural identification and assessment issues. The field of seismic engineering is continuously looking for new strategies and methods, which empower the designers and make them able to obtain more accurate response predictions. Researchers are involved in this process and are called to successfully encounter new challenges emerging from the increasing need for the assessment of existing constructions, especially when assuming strategic roles. As is also reflected by the papers presented in the Special Issue, the continuous advances of the research in this field moves across two basic directions. On the one hand, there is the direction of the robustness and the reliability of the recent nonlinear seismic assessment methods (static, dynamic, incremental dynamic). Several approaches can be followed to predict the response of structures to strong ground motions; however the results coming from each of them are in some cases conflicting and not always amenable to easy interpretation. On the other hand, the reliability of structural models still remains a major task of structural engineering and of seismic engineering in particular. Mathematical models have to reproduce the physics of structures and its evolution during complex damaging processes. Global and local models tend to reflect this by minimizing the loss of information. In the Special Issue, we are proud to present state-of-the-art research findings described in detail in 9 papers authored by 27 researchers of different universities in Italy, California (USA), Greece and United Kingdom. The papers deal with the seismic analysis and risk mitigation aiming to address different purposes by proposing numerical, analytical approaches and experimental tests

    Monte Carlo analysis of masonry structures under tsunami action: Reliability of lognormal fragility curves and overall uncertainty prediction

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    Tsunami vulnerability of coastal buildings has gained more and more interest in recent years, in the consciousness of what losses may be caused. The improvement of the available approaches for the quantitative estimation of the probability of building damage and for defining possible strategies for risk mitigation is an actual goal. In this framework, several authors have provided empirical fragility curves based on field surveys after tsunamis. Nevertheless, a predictive approach based on analytical fragility curves, which can be extended to many classes of buildings, is essential for the scopes of civil protection and risk mitigation. In this paper, an approach for the construction of fragility curves, proposed for masonry structures under tsunami waves, is discussed and refined in the part regarding the assignment of the uncertainties. Further, an assessment of the reliability of the lognormal fragility distribution is carried out based on a Monte Carlo simulation applied to 4 classes of buildings. Here, it is shown that Monte Carlo analysis allows a direct evaluation of the uncertainties without the need to resort to ambiguous regression analyses and rules of combination of the uncertainties of demand and capacity based on the regression analysis results or other uncertainty estimation approaches

    BIAXIAL CURVATURE AND DUCTILITY CAPACITY OF RC COLUMN BASE CROSS SECTIONS

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    The deformation performance of the base cross sections of reinforced concrete buildings is fundamental when large seismic events occur allowing the structure to have large excursions in nonlinear field and guaranteeing an overall ductile behaviour. It is well known that the axial force acting on columns significantly reduces the curvature capacity of the sections and for this reason the technical codes give design criteria stating a limitation in order to preserve the displacement capacity. It is also recognized that when biaxial bending occur the cross section undergo a loss in strength capacity. Starting the study of from Bresler (1960), which provided suitable expression to predict 3D limit interaction surfaces, several numerical and analytical models were developed to take into account the biaxial interaction in strength. Simultaneously it is noteworthy to point out that the presence of biaxial bending also influences the deformation capacity of sections causing in most of the cases a relevant loss of the curvature and ductility available with respect to the one owned along the principal axes. This important issue is not faced by technical codes and not exhaustively treated in scientific literature as it was done for strength. Moreover nonlinear structural models based on lumped plasticity do not take into account these interaction aspects when defining plastic hinge properties in terms of curvature capacity. The paper presents a numerical study in which the deformation capacity of RC cross sections subjected to axial load and biaxial bending is investigated by means of a fiber discretization. A procedure for the numerical definition of biaxial domains of ultimate curvature, yielding curvature and curvature ductility is provided and the sensitivity of the biaxial deformation performance to some geometrical and mechanical parameters (aspect ratio, concrete strength and confinement efficacy) is discussed.The deformation performance of the base cross sections of reinforced concrete buildings is fundamental when large seismic events occur allowing the structure to have large excursions in nonlinear field and guaranteeing an overall ductile behaviour. It is well known that the axial force acting on columns significantly reduces the curvature capacity of the sections and for this reason the technical codes give design criteria stating a limitation in order to preserve the displacement capacity. It is also recognized that when biaxial bending occur the cross section undergo a loss in strength capacity. Starting the study of from Bresler (1960), which provided suitable expression to predict 3D limit interaction surfaces, several numerical and analytical models were developed to take into account the biaxial interaction in strength. Simultaneously it is noteworthy to point out that the presence of biaxial bending also influences the deformation capacity of sections causing in most of the cases a relevant loss of the curvature and ductility available with respect to the one owned along the principal axes. This important issue is not faced by technical codes and not exhaustively treated in scientific literature as it was done for strength. Moreover nonlinear structural models based on lumped plasticity do not take into account these interaction aspects when defining plastic hinge properties in terms of curvature capacity. The paper presents a numerical study in which the deformation capacity of RC cross sections subjected to axial load and biaxial bending is investigated by means of a fiber discretization. A procedure for the numerical definition of biaxial domains of ultimate curvature, yielding curvature and curvature ductility is provided and the sensitivity of the biaxial deformation performance to some geometrical and mechanical parameters (aspect ratio, concrete strength and confinement efficacy) is discussed

    Strategies for Waste Recycling: The Mechanical Performance of Concrete Based on Limestone and Plastic Waste

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    Recycling is among the best management strategies to avoid dispersion of several types of wastes in the environment. Research in recycling strategies is gaining increased importance in view of Circular Economy principles. The exploitation of waste, or byproducts, as alternative aggregate in concrete, results in a reduction in the exploitation of scarce natural resources. On the other hand, a productive use of waste leads to a reduction in the landfilling of waste material through the transformation of waste into a resource. In this frame of reference, the paper discusses how to use concrete as a container of waste focusing on the waste produced in limestone quarries and taking the challenge of introducing plastic waste into ordinary concrete mixes. To prove the possibility of reaching this objective with acceptable loss of performance, the mechanical characteristics of concrete mixed with additional alternative aggregates classified as waste are investigated and dis-cussed in this paper through the presentation of two experimental campaigns. The first experimental investigation refers to concrete made with fine limestone waste used as a replacement for fine aggregate (sand), while the second experimental program refers to the inclusion of three types of plastic wastes in the concrete. Different mixes with different percentages of wastes are investigated to identify possible fields of application. The experimental results indicate that use of limestone quarry waste and use of plastic waste are possible within significant percentage ranges, having recognized a limited reduction of concrete strength that makes concrete itself appropriate for different practical applications

    Tsunami Vulnerability Evaluation for a Small Ancient Village on Eastern Sicily Coast

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    The Ionian sea is prone to tsunamis due to its proximity to the Calabrian subduction zone, which is one of the major tsunamigenic areas of the Mediterranean. The tsunami disaster risk is, nowadays, significantly higher due to the increased exposure of buildings as a result of the economic and touristic growth of the Mediterranean coastal areas. This study focuses on Marzamemi, a small village in the western coast of Sicily, since its morphology and human presence amplify the need to assess its buildings’ vulnerability. The main objective of this research is to quantify the building vulnerability to tsunami hazards using a physical and realistic tsunami scenario. For this purpose, the relative vulnerability index of the buildings in Marzamemi was calculated by means of an improved Papathoma Tsunami Vulnerability Assessment (PTVA) model. The presented approach has three main improvements: (a) a probabilistic tsunami scenario was used; (b) a realistic signal of water surface linked with a specific focal mechanism was adopted; (c) a tsunami wave was propagated from offshore to nearshore using a nonlinear numerical model. The good results of the proposed methodology make it very useful for coastal risk planning conducted by decision makers and stakeholders

    Definition of seismic vulnerability maps for civil protection systems: The case of lampedusa Island

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    The opportunity to locate and quantify the major criticalities associated to natural catastrophic events on a territory allows to plan adequate strategies and interventions by civil protection bodies involved in local and international emergencies. Seismic risk depends, most of all, on the vulnerability of buildings belonging to the urban areas. For this reason, the definition, by a deep analysis of the territory, of instruments identifying and locating vulnerability, largely favours the activities of institutions appointed to safeguard the safety of citizens. This paper proposes a procedure for the definition of vulnerability maps in terms of vulnerability indexes and critical peak ground accelerations for mid-small urban centres belonging to Mediterranean areas. The procedure, tested on the city centre of the Island of Lampedusa, is based on a preliminary historical investigation of the urban area and of the main formal and technological features of buildings involved. Moreover, the vulnerability of the constructions is evaluated by fast assessment methods (filling of evaluation forms). The vulnerability model, allowing the definition of the fragility curves, is calibrated on the basis of the results of an identification process of prototype buildings, selected to be adequately representative. Their characterizations have been provided using the results of an experimental dynamic investigation to develop high representative numerical model. Critical PGA values have been determined by pushover analyses. The results presented provided an unambiguous representation of the major criticalities with respect to seismic vulnerability and risk, of the city centre of the island, being a suitable tool for planning and handling of emergencies
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