1,721,002 research outputs found
Multi-performance evaluation of traditional and low-damage non-structural components
Get PDFNon-structural components include all the building elements not part of the main loadbearing system of a structure or an industrial facility. These components are designed to provide specific performance, such as controlling the passage of heat or resisting to fire, while the seismic behaviour is typically neglected in the design process. Nevertheless, the response of these elements can significantly affect the building functionality after earthquakes, even for low-intensity events, and their poor performance can result in substantial economic losses and business interruption. Consequently, the non-structural damage has a severe impact on the post-earthquake building recovery in addition to the potential risk to life safety.
As either the earthquake engineering community or the public demand a higher level of earthquake protection, improving the seismic performance of structural systems is not enough and the expectation of advanced seismic behaviour for non-structural components is demanded. The need for reduction of non-structural seismic risk is thus being recognized fundamental in the decision-making process and in the performance-based seismic design the attention is nowadays focusing on both the harmonization of structural/non-structural performance and the development of damage-control or low-damage non-structural systems.
Considering the previous background, this Thesis mainly aims to: 1) provide evidence on the convenience of implementing innovative low-damage technologies for non-structural components, 2) highlight the importance of including the study of the seismic performance of new or retrofitted elements within an integrated multi-performance design approach.
The Thesis initially provides an overview of the damage states/mechanisms evolving during earthquake shakings in different typologies of non-structural elements, i.e. architectural elements, building services and contents. Fragility curves developed from past experimental research are also collected; in fact, determining which parameters mainly influence the failure modes and when a damage condition is achieved can help in the proposal of new solutions.
Then, a literature review can be found on the innovative damage-mitigation technologies developed during the last decades for both structural and non-structural components. These solutions can be combined to define an integrated high-performance earthquake-proof building system. The Thesis also describes the experimental investigations (1D shake-table testing) carried out on a new earthquake-resistant solution proposed with the aim of reducing the
seismic demand on non-structural systems anchored to concrete structures, i.e. supplemental damping is added to post-installed fasteners. The test results confirm the beneficial effects of this solution to seismically protect the non-structural elements for expansion or chemical fasteners in both un-cracked and cracked concrete.
The convenience of implementing low-damage systems is thus investigated through numerical and experimental studies. Cost/performance-based evaluations of multi-storey buildings comprising different traditional vs. low-damage structural systems (frames, walls) and non-structural elements (facades, partitions, ceilings) are performed to highlight that these solutions are able to withstand earthquake shakings with negligible damage, consequently
reducing the expected losses in terms of repair costs and downtime. The high performance of such types of technologies, and particularly of the integrated system, is also proved through 3D shake-table tests of a 1:2 scale two storey-two bay building, consisting of a low-damage timber-concrete structural skeleton and high performance or damage-control non-structural components/envelopes. The experimental campaign is fully described from the design of the
specimen and of its structural/non-structural detailing, to the construction and assembly phases, to the test setup. Preliminary experimental results are provided, focusing on the seismic demand/performance of all the tested non-structural components.
Finally, the importance of implementing a multi-performance design approach for nonstructural components is presented in the last part of the Thesis. An integrated seismic & energy cost/performance investigation of traditional vs. low-energy and/or low-damage façade systems is initially carried out, to highlight that the dynamic behaviour of these systems must be studied to better design the non-structural detailing. Furthermore, a multi-criteria decision analysis, including all the non-structural performance (structural, architectural, long-term) and the initial cost as criteria/sub-criteria, is proposed and developed in order to drive decisions on non-structural systems, i.e. defining the best solution/detailing among alternatives
Seismic assessment and finite element modeling of traditional vs innovative point fixed glass facade systems (PFGFS)
Get PDFIn the last decades, recent earthquakes have further highlighted the high vulnerability of non-structural components. Post-earthquake damage due to building envelope, equipment and building contents can lead to substantial economic losses in terms of repair costs and daily activity interruption (downtime). Moreover, non-structural damage can represent a life-safety threat for both occupants and pedestrians. These considerations confirm the crucial need for developing low-damage systems for either structural or non-structural elements. This paper aims to assess the seismic performance of glazed facade systems, widely adopted in modern buildings, focusing on point fixed glass facade systems (PFGFSs), also referred to as “spider glazing”. In this work, a numerical investigation is developed to study the seismic performance of such systems at both local-connection level through a 3D FEM in ABAQUS as well as at global system level through a simplified lumped plasticity model in SAP 2000 to assess the overall in-plane capacity of the facade. Based on the local connection and global facade system behavior, a novel low-damage connection system is herein proposed, and a parametric study is carried out on the key parameters influencing the facade capacity. The benefits of implementing low-damage connection details are highlighted by an increase of the in-plane capacity of the facade system when compared to a traditional solution. To further investigate the potential of the proposed low-damage details in preserving the integrity of the facade system itself, non-linear time history analyses have been carried out on a case-study building equipped with the innovative PFGFSs.Architectural Technolog
Eco-friendly exoskeletons for enhancing resilience of the built environment.
No full textRecent natural disasters in the form of earthquakes and extremes events associated to climate-change have further confirmed the need for an urgent effort to improve the resilience of the built environment. In parallel, resource-efficient structural design is growing in interest, and major effort has been focusing to the implementation of nearly-zero energy buildings or net zero carbon construction by using low-emission and eco-friendly materials. Despite this ambitious goal for designing new buildings, the renovation of existing ones in a low-carbon manner remains challenging. This is the case when the upgrading must address both energy performance and other resilience requirements, for example buildings featured by high seismic vulnerability and poor energy performance, that pre-date modern codes that regulate seismic design and energy performance. Even though several solutions have been proposed for the integrated renovation of existing buildings, this study identifies the advantages of, and proposed a framework for, a holistic approach based on a novel technology implementing timber-based, low-damage external exoskeletons. The seismic-resistant low-damage technology considered is the Prestressed-Laminated (Pres-Lam) timber technology, proposed at the University of Canterbury, and implemented in several buildings around the world. The exoskeleton allows for the seismic strengthening/retrofitting of the existing building, and provides the support for a “double-skin” system, also allowing for the improvement of the energy efficiency and for architectural renovation, ensuring an holistic and integrated rehabilitation of buildings. All the components used (i.e., structural/non-structural) are based on dry connections, thereby enabling demountablity/reusability at end of life. This study demonstrates the potential of this technology by means of structural/ energy numerical simulations on a case study building. Furthermore, it points out the importance of a careful and efficient use of the resources in terms of materials used, for implementing an integrated approach that ultimately improves the resilience, efficiency, and sustainability of the built environment
Seismic performance of Point Fixed Glass Facade Systems through Finite Element Modelling and proposal of a low-damage connection system
Get PDFAmong glazed curtain walls, the growing interest in Point Fixed Glass Facade Systems (PFGFS), simply known as “Spider Glazing”, is mainly due to their aesthetics, architectural attractiveness and high
transparency they can provide when compared to more traditional framed glass facades. PFGFS are in fact
punctually attached to the structure by using spider arms and bolted fittings. However, some PFGFS
solutions have shown an unexpected moderate seismic vulnerability in recent earthquake events, as a
consequence of inadequate connection detailing. As part of current seismic design philosophy, high
structural and non-structural damage is accepted under a design-level earthquake. This inevitably leads to
high post-earthquake losses in terms of both repair costs and business interruption for the damaged
buildings. Therefore, nowadays the need for research efforts towards the development of low-damage
technologies for the overall building system, including structural and non-structural components, is
increasingly recognized.
This paper aims at investigating the seismic performance of PFGFS through numerical studies at both localconnection level, by advanced non-linear FEM modelling implemented in ABAQUS software, and at globalfacade system level, through a simplified lumped plasticity macro-model developed in SAP2000 program. Non-linear static (PushOver) analyses have been carried out to assess the overall in-plane capacity of the facade. Based on the numerical outcomes obtained for a PFGFS consisting of traditional connections (i.e., available on the market), a novel low-damage system has been proposed. This solution comprises horizontal slotted holes for the bolted connection of the spider arms to the supporting structure. A parametric analysis, involving the variation of the slotted hole length, has been finally performed to study the effectiveness of the proposed solution. Results highlight the improvement of the in-plane capacity of the PFGFS, specifically an increase of the maximum allowable inter-storey drift ratio from 1.17% for the traditional system to 2.49% for the low-damage connection
External timber-based low-damage exoskeletons for enhanced structural safety and energy efficiency.
No full textThe European building stock, mostly built post-World War II with no regard to seismic design and energy efficiency principles, is unsurprisingly facing significant safety and energy efficiency challenges. The structural/seismic vulnerability of existing buildings has been further confirmed by recent earthquake disasters (e.g., L’Aquila 2009, Emilia 2012, Centre Italy 2016, Turkey & Syria 2023), whereas the energy inefficiency is underscored by high energy consumption rates. An unprecedented effort is therefore required to achieve energy savings and decarbonization targets by 2030 and 2050, respectively, to meet the ambitious goals of the European Green Deal. Although several technical solutions are available for improving the energy efficiency, it is advantageous to pursue integrated renovation strategies (i.e., structural and energy efficient), especially when dealing with buildings located in zones with moderate-to-high seismicity.
This work explores the application of exoskeleton-type solutions for integrated building renovation. Specifically, external load bearing systems consisting of low-damage timber-based structural members (i.e., Pres-Lam technology), that upgrade the seismic performance by working in parallel with the existing building. Such solution is attractive, given the potential to execute the intervention entirely from outside the building, limiting occupant disruption and avoiding decanting of inhabitants. This aspect is crucial in motivating owners to choose a combined renovation, rather than just focusing on the energy one. If the system is structurally unsafe, even low-to-moderate earthquakes can easily damage it, making the energy improvements ineffective. Concurrently, the exoskeleton operates as the support for a high-multi-performance “double-skin” facade system, contributing to enhanced energy efficiency and facilitating a holistic renovation.
The main goal of this work is to prove the effectiveness of the proposed integrated renovation strategy through an illustrative case study. The overall performance of both the as-built and the retrofitted structures is assessed by means of seismic and dynamic energy analyses. Building on such results, a loss assessment procedure is implemented to quantify the overall socio/economic/environmental impact in the building lifespan. The findings provide evidence of the efficiency of the proposed strategy to enhance the seismic resilience and the environmental sustainability of the solution
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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