1,721,010 research outputs found
Residual out-of-plane capacity of infills damaged by in-plane cyclic loads
No full textDuring earthquakes, infills are subjected to In-Plane (IP) and Out-Of-Plane (OOP) actions. In the case of strong earthquakes, infills may progressively change their mechanical behavior resulting in a reduction of IP and OOP stiffness and strength. Recent earthquakes have proved that the OOP collapse of infills is a diffused mechanism also for buildings designed to resist seismic events in agreement to the most modern codes. This is potentially a very dangerous event with risk for human health. The strong interaction between IP and OOP behavior of infills traduces in a progressive reduction of the OOP strength. The IP damaging loads may cause a loss of the OOP capacity not predicted during the design process or during the safety assessment. Unfortunately, a very low number of experimental tests is available in the literature that does not allow definitively reliable prediction laws for the degrading of the OOP mechanical properties. Further, only in few cases codes suggest adequate strategies to face this question. For what above, in this paper the reduction of OOP stiffness and strength because of the IP damage is studied by an extended numerical experimental campaign based on FE models to be considered as complementary of the few laboratory experimental tests available in the literature. On the base of the numerical results, a proposal for the prediction of the variation of the mechanical characteristics of infills with respect to OOP actions is presented after an extended discussion on the existing strategies. The nonlinear behavior of infills and the arch effect between infill and the surrounding frame, where effective, have been replicated by the FE models here discussed, trying to simulate the real case of unreinforced masonry (URM) infills
Seismic risk scenario for the historical centre of castelpoto in Southern Italy
No full textThe study proposed a seismic vulnerability methodology applied to the historical centre of Castelpoto, located in the province of Benevento (Southern Italy). The seismic vulnerability of the examined aggregates was examined using an index-based procedure specifically developed for structural masonry compounds. The structural details and specific characteristics of building aggregates are crucial in determining the seismic vulnerability of buildings in urban environments. Parameters such as the plan configuration, size, and layout of buildings, including the thickness, height of the masonry walls and the connections among different components of the construction, were appropriately considered, since all might have an impact on their seismic performance. Furthermore, the type of masonry, the strength and composition of the mortar, as well as the quality of constructions, can also contribute to the global seismic performance of buildings. These structural parameters, collected in the used form, were correlated to the Masonry Quality Index (MQI) to provide an exhaustive assessment of the capacity (in-plane and out-of-plane mechanisms) of the bearing elements towards seismic loads. Secondly, the susceptibility to damage of the existing building stock was evaluated by applying a parametric simulation of damage scenarios adopting an appropriate Intensity Prediction Equation (IPE). To this purpose, fault models were acquired from the Database of Individual Seismogenic Sources (DISS) and the considered IPE was validated according to the Italian Macroseismic Database (DBMI). Thus, the proposed research aims to highlight how an accurate assessment of masonry strength is crucial during the inspection phase to optimise the prediction of the expected damage scenario allowing for effective risk mitigation in urbanised contexts
Numerical modelling of out-of-plane response of infilled frames: State of the art and future challenges for the equivalent strut macromodels
No full textInfill-frame interaction constitutes a still open question both in research and in practicing engineering. Computational models used to predict this interaction are, in most cases, addressing the estimation of the response of the infilled frames when subjected to actions parallel to their plane. However, the observation of the post-earthquake damage has demonstrated that infills, weakened by the in-plane actions, may fail out-of-plane increasing the risks associated to the earthquake scenarios. In spite of this, different studies have shown that infills, if properly designed and supported by the frame, exhibit a significant strength and displacement capacity when called to resist to out-of-plane actions, offering the possibility to develop an arching mechanism in their deformed configuration. The prediction of the combined inplane out-of-plane response prefigures the new goal of the seismic assessment of masonry infilled frames. This paper presents an in-depth literature review of the capacity models developed for the prediction of the out-of-plane response of infilled frames, from the first flexural based computational models to the models implementing the arching action theory in their formulation. A comparison between the results obtainable is provided in order to compare the models reliability against the results of different experimental tests. A final discussion is devoted to the effectiveness the recent integrated in-plane/out-of-plane macromodels used in 3D structural models. A new promising approach, based on the use nonlinear fibersection elements, is also outlined providing a numerical testing of the capacity of such elements to naturally account for the out-of-plane arching mechanism
Seismic analysis and risk mitigation of existing constructions
Full text linkFollowing a thorough and lengthy procedure, we would like to thank all contributors for their highest calibre papers,
which comprise the Special Issue on “Seismic analysis and risk mitigation of existing constructions” 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
Fundamental period of infilled reinforced concrete frame structures
No full textThe fundamental period of vibration appears to be one of the most critical parameters for the seismic design and assessment of structures. In the present paper, the results of a large-scale analytical investigation on the parameters that affect the fundamental period of reinforced concrete structures are presented. The influence of the number of storeys, the number of spans, the span length, the infill wall panel stiffness and the percentage of openings within the infill panel on the fundamental period of infilled RC frames was investigated. Based on these results, a regression analysis is applied in order to propose a new empirical equation for the estimation of the fundamental period. The derived equation is shown to have better predictive power compared with equations available in the literature
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
Iterative Finite Element Analysis of Concrete-Filled Steel Tube Columns Subjected to Axial Compression
Full text linkSince laboratory tests are usually costly, simulating methods using computers are always under the spotlight. This study performed a finite element analysis (FEA) using iterative solutions for simulating circular and square concrete-filled steel tube (CFST) columns infilled with high-strength concrete and reinforced with a cross-shaped plate (comprising two plates along the columns that divide the hollow columns into four equal sections) with and without opening. For this reason and for validation purposes, the columns had length of 900 mm, width/diameter of 150 mm and wall thickness of 3 mm. In this study, unlike in some other studies, the cross-shaped plate was assumed to be fixed at the top and the bottom of a column, and the columns were subjected to axial compression pointed in the center. The outcomes revealed that the cross-shaped plate could improve the axial strength of both circular and square CFST columns; however, the structural performance of the square CFST columns changed: local outward buckling was observed after inserting the cross-shaped plate. By inserting an opening on the cross-shaped plate, the bearing capacity of the circular CFST columns was further improved, while the square CFST columns experienced a decline in their ultimate bearing capacity compared with the corresponding models without the opening. The lateral deflection also improved for the circular CFST columns by adding the reinforcement. However, for the square CFST columns, while it initially improved, increasing the thickness of the cross-shaped plate inversely influenced the lateral deflection of the square CFST columns. The results were also compared with some available codes, and a good agreement was achieved with those outcomes
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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