1,720,996 research outputs found
Codification and research for mass timber buildings in selected seismic regions: An overview
No full textSince the late 2000's, many countries around the world have experienced rising interest in mass timber construction in commercial and mixed-use building applications. Globally, wood design and research communities have invested heavily in research and development (R&D) to make mass timber viable for large scale, multi-story buildings, targeting commercial markets. Due to the difference in historical design/fabrication practices, local regulatory rules, and cultural differences, the status of mass timber codification and research development are not uniform throughout the world. In this paper, an overview of recent trends in manufacture, codification, and research on mass timber systems is provided. Specifically, this overview was divided into five distinct topics, namely mass timber material standards, mandatory building/design requirements, non-mandatory design guidelines, different approaches to lateral design, and notable mass timber research efforts in the recent decades. Due to the limitation of the authors' experience, only selected regions around the world are covered in this review
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
Optimized seismic design and dynamic response analysis of mass timber rocking wall lateral system
No full textIncludes bibliographical references.2023 Spring.As societal expectations for urban development move towards a more resilient and sustainable focus, renewable construction materials are gaining more attention in the past decade and for the foreseeable future. One of the most well-known environmental challenges facing society today is greenhouse gas emissions, specifically carbon dioxide. The building and construction industry is one of the largest contributors to global carbon dioxide emission, which occurs during the construction and occupancy life cycle of buildings. Timber is considered as a sustainable and carbon-friendly solution for building systems due to its renewable nature and the potential ability to store carbon long term.
Mass timber is a family of engineered wood products that are produced from smaller timber components joined together using glue or mechanical connectors. Utilizing mass timber floor system with glulam gravity frame gives the possible solutions to create tall timber buildings with flexible floor plan applications. Mass timber gravity system can be combined with traditional steel and concrete lateral systems. But there are benefits to exploring a lateral system made also out of mass timber products. Firstly, this will enable a more streamlined construction process because the construction will only require a timber construction crew. Secondly, past studies revealed that a new type of lateral resisting system called mass timber rocking walls can potentially improve the resilience of the building during earthquakes. This system utilizes mass timber products as wall panels and unbonded post-tension bars to tie the rocking panel to the foundation. The rocking wall lateral system can achieve a ductile response and assure recentering capability. Energy dissipation devices such as U-shaped flexural plates (UFPs) are used as supplement dampers to dissipate energy and reduce accelerations. The use of replaceable dampers also allows localized damage to specific components that can be replaced after large seismic events.
In this thesis, a simplified numerical model for dynamic response prediction of mass timber building with PT rocking wall system was developed and validated with shake table test data. The concept of the simplified model is to concentrate the nonlinearity of that system into a few nonlinear rotational springs and represent rocking wall panel with elastic lumped mass spring series to reduce the computational cost. The simplified numerical model was first validated using the data from the NHERI TallWood 2-story tests conducted in 2017. Then the author expanded the simplified modeling concept using SAP2000 for the 10-story mass timber building which will be tested in spring 2023. Another 2D analytical model of the 10-story mass timber building is also developed to consider torsional responses.
An optimized performance-based seismic design (PBSD) frame is developed by expanding the existing PBSD framework through an automated procedure to obtain optimized design solutions utilizing Genetic Algorithms (GA). While simplified models are much more computationally efficient than traditional FEM models, a large amount of simulation needed for optimized PBSD using GA still needs hours of simulation to complete. To enable a more reasonable time frame for the proposed PBSD optimization, a generalized artificial neural network (ANN) model was trained using simplified mechanical models and replaced the nonlinear time history simulation process in the GA search for optimized PBSD. A web-based automatic design application as well as a MATLAB program was developed to enable the selection of rocking wall key design parameters based on the tools developed in this study.
The author also actively participated in the collaborative research and development effort that leads to the testing of the NHERI TallWood 10-story building. Relevant research and design work conducted by the author as part of the testing project is also presented here
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
Cost effectiveness of beam-column gravity systems for mass timber buildings
No full textIncludes bibliographical references.2020 FallMass timber construction (MTC) has grown in popularity in recent decades, leading to the adoption of new construction types for MTC to be included in the 2021 International Building Code (IBC). Estimating the cost of mass timber construction is uniquely different and less understood than the cost estimation of concrete, steel, and light-framed wood buildings. This thesis will provide a better understanding of cost estimation of mass timber construction by investigating the cost sensitivity of key design features for a mass timber gravity system. An algorithm consisting of automated design and cost estimation is used. The algorithm implements strength and serviceability limits and the building type requirements defined by the IBC. The major system components and design choices that significantly affect cost are found and discussed
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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