1,720,960 research outputs found
SEISMIC STRENGTHENING OF AN EXISTING RC FRAME BUILDING DESIGNED FOR GRAVITY LOADS
No full textIn Italy, most of the residential buildings were constructed before 1981, when only 25% of the national territory was classified as seismic; the larger proportion of this building stock is Reinforced Concrete (RC) structures. These building designed only to resist to gravity load, shows several structural deficiencies under seismic action related both to the lack local details (e.g. absence of transverse reinforcement in beam-column joints) and poor structural material properties. The vulnerability of existing buildings designed without seismic arrangements was highlighted by recent earthquake that caused damage and several buildings collapse. Nowadays, the rehabilitation of existing structures, taking into account energetic and sustainability requirements, is a newsworthy and challenging task. In this work, the seismic performances of an existing, gravity load designed, RC frame residential building located in Mugnano di Napoli (NA, Italy) were investigated. First, the assessment of the existing structure's performance in a code-based approach was performed; then, a strengthening intervention by means of Orthogonal Steel Exoskeleton system was designed through a detailed step-by-step procedure. The efficiency of the proposed global strengthening intervention were assessed by means of a non-linear static analyses. Designed interventions allows to strongly increase the structural performance of the investigated case study
Orthogonal steel exoskeleton for low impact and rapid execution retrofitting of existing buildings: state-of-the-art and structural concept
No full textThe use of exoskeletons, intended as additive structures applied in a widespread way externally to the building to be protected, constitutes a valid alternative to common intervention techniques for the seismic retrofit of existing buildings. Among many typological solutions present in the literature, in the present work, the orthogonal 2D steel exoskeletons (called EXO 2DA) have been analysed in detail. These systems, made as truss shear walls placed orthogonally to the facade of the building, can be effectively used for the strengthening of low-mid-rise buildings. In the present work, after a thorough state-of-the-art and a critical analysis of recent realizations, a kit-constructive system, suitable for prefabrication, was conceived
In-plane Tests of Cold-Formed Steel Shear Walls Sheathed with Gypsum Sheathing
No full textThe use of Cold-Formed Steel (CFS) sections has gained attention due to their advantages, including lightweight construction and rapid implementation in prefabricated modular systems. Additionally, their utilization in regions with significant seismic hazards should be in compliance with international building codes. Therefore, it is essential to examine how these elements made by CFS sections perform as lateral load-resistant systems under earthquake conditions. One of the types of earthquake-resistant systems in structures constructed with CFS sections is shear walls made from steel frames with CFS sections sheathed with gypsum-based panels. Thesewalls play a crucial role in enhancing the seismic performance of such structures. This study, conducted at the Structural Laboratory of Federico II University, aims to investigate the seismic behaviour of these walls at full scale level through experimental tests. In this campaign of experiments, four wall prototypes were subjected to inplane testing. One test evaluated the behaviour of a shear wall under monotonic loading, while the other three tests examined the behaviour of thewalls under cyclic loading using the CUREE protocol. Various parameters were investigated in order to capture their influence on the seismic behaviour of the shear walls, including the effect of cyclic loading, spacing of fasteners connecting gypsum-based panels to steel profiles, and wall’s aspect ratio. The paper presents the experimental program, as well as the descriptions of wall prototypes, setup, instrumentation, and loading protocols, together with the main results, as load-displacement response curves and collapse mechanisms
Test-Based Assessment of the Seismic Response of Bracing Systems for Concealed Grid Suspended Ceilings
No full textDespite not directly contributing to a structure’s load-bearing capacity, nonstructural elements like partitions, cladding, ceilings, floor finishes, and facades play a pivotal role in the overall building design and occupant safety. Their susceptibility to damage during seismic events, however, can lead to substantial economic losses, business interruptions, and potential risks to occupants. Focusing on concealed grid suspended ceiling systems, this study focuses on enhancing their seismic resilience introducing and experimentally evaluating two innovative bracing systems (Typology N and Typology W) that utilize steel members, already used in non-seismic application, as braces. Unlike prior research using shake tables, this study employs a specially designed set-up on a universal testing machine, offering a cost-effective and efficient approach for cyclic testing and considering the spatial variability of seismic loads. As a complementary task, component-level tests were conducted on the compressed strut to extend the results for suspended ceiling systems having suspension height up to 2 meters. The results show that Typology N performs better than Typology W, with 1.7 times greater resistance and 2.5 times greater stiffness on average, demonstrating the importance of considering different directions of horizontal seismic loading in the performance assessment. The study provides valuable insights, including design resistance values and a step-by-step procedure for determining the maximum ceiling area that a single bracing system can cover, aiding in optimizing bracing system selection and mitigating seismic vulnerability in concealed grid suspended ceilings for seismic-prone regions
Seismic strengthening of isolated RC framed structures through orthogonal steel exoskeleton: Bidirectional non-linear analyses
No full textThe catastrophic effects of recent earthquakes around the world have highlighted the vulnerability of civil buildings; in Europe, most of the existing buildings were built after World War II and since they have largely exceeded their useful life, are characterized by a high vulnerability linked both to the durability of the materials and to the lack of seismic provisions in design. The current trend in constructional field is to design interventions aimed at the seismic and energy improvement of these structures jointly, in order to achieve a sustainable and integrated retrofit intervention. To this aim, the use of 2D orthogonal steel exoskeletons for the seismic strengthening represents a suitable solution, providing at the same time an enhancement in thermal insulation, through a ‘double-skin’ solution. Due to the growing interest in the design of steel exoskeleton interventions, a detailed dynamic characterization of this external strengthening solution is needed. In this framework, the present work, aims to investigate the effectiveness of the investigated strengthening solution by means of bi-directional non-linear dynamic analyses. Extensive numerical analysis was carried out. The selected case-study is an Italian existing pre-1980 s RC frame building located in Mugnano di Napoli (NA, Italy), which is a medium-high seismic hazard site in Italy (peak ground acceleration equal to 0.156 g). Two alternative strengthening solutions were numerically investigated by means of non-linear time-history and incremental dynamic analyses performed applying fifteen bidirectional ground motions on three-dimensional numerical models. The results of the dynamic non-linear analyses allow to quantify more appropriate performance indicators, both in terms of expected demand and overall collapse capacity, useful for the development of optimization strategy and design of exoskeleton system. The results highlighted that both the investigated strengthening scenarios allow to increase the stiffness of the existing building and allow it to meet the current code safety requirements reducing also the residual inter-storey drift. The obtained results are not strictly related to the investigated case study, but can be extended to all the structures retrofitted that follows the presented design procedure
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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