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Author: Yucel Alp Publisher: ISBN: Category : Languages : en Pages : 170
Book Description
This thesis presents the results of a finite element study of the behavior of the shear links with reduced web sections subjected to cyclic and monotonic loading protocols, for use in seismic-resistant steel Eccentrically Braced Frames (EBFs). The capacity design philosophy for EBFs relies on the principle that the link, where inelastic deformation is intended to occur in an earthquake, must be the weakest element in the frame. One approach to satisfying capacity design requirements of EBFs is to decrease the strength of the links. Removing some portion of the link web is one method to reduce the shear capacity of the link. Twenty-one finite element models were analyzed under cyclic and monotonic loading protocols. Finite element models were based on a W18x40 shear link, without web holes, tested in an actual experiment. Modeling techniques and material definitions were validated using the same experimental findings. The finite element shear link models with various hole patterns, locations, and percent web removal were then analyzed to investigate the effect of removing material from the web on the behavior of the shear link in terms of strength and rotation capacity. This study suggests that shear links with reduced web sections provide a potentially viable method to reduce link shear strength
Author: Yucel Alp Publisher: ISBN: Category : Languages : en Pages : 170
Book Description
This thesis presents the results of a finite element study of the behavior of the shear links with reduced web sections subjected to cyclic and monotonic loading protocols, for use in seismic-resistant steel Eccentrically Braced Frames (EBFs). The capacity design philosophy for EBFs relies on the principle that the link, where inelastic deformation is intended to occur in an earthquake, must be the weakest element in the frame. One approach to satisfying capacity design requirements of EBFs is to decrease the strength of the links. Removing some portion of the link web is one method to reduce the shear capacity of the link. Twenty-one finite element models were analyzed under cyclic and monotonic loading protocols. Finite element models were based on a W18x40 shear link, without web holes, tested in an actual experiment. Modeling techniques and material definitions were validated using the same experimental findings. The finite element shear link models with various hole patterns, locations, and percent web removal were then analyzed to investigate the effect of removing material from the web on the behavior of the shear link in terms of strength and rotation capacity. This study suggests that shear links with reduced web sections provide a potentially viable method to reduce link shear strength
Author: Publisher: ISBN: Category : Earthquake resistant design Languages : en Pages : 221
Book Description
The primary component in eccentrically braced frames (EBF) is the link as its plastic strength controls the design of the frame as well as the entire building within which it is installed. EBFs are the first part of building design and every other component is sized based on the forces developed in the link. Oversized link elements lead to the use of unnecessary materials and can increase construction costs. Additionally, the advantages of using a continuous member of the same depth for both the link and the controller beam (in terms of the cost and the time) motivates researchers to find a way to control the link strength in conventional EBFs. Previous studies on the link-to-column connections in EBF have shown that the links are likely to fail before reaching the required rotation due to fractures at low drift level. Moreover, improving the strength of the links in EBF depends primarily on their ability to achieve target inelastic deformation and to provide high ductility during earthquakes. Therefore, in this study, the concept of tuned link strength properties in EBF, T-EBF, is experimentally introduced as a solution to improve the performance of the link in conventional EBF by cutting out an opening in the link web. Furthermore, a new brace-to-link connection is proposed to bolt the brace member with the link in contrast to the conventional method of welding them. This new idea in continuous beam design was investigated to verify the stability of the tuned eccentrically braced frame, either welded or bolted, with a bracing member. A total of four full-scale cyclic tests were conducted to study the ability of T-EBF to achieve inelastic deformation. The specimens have two different cross sections: W18x76 and W16x67, two different sections where the brace was welded to the link, and two other specimens at different sections where the brace was bolted to the link were examined. The experimental results indicate that the link in T-EBF can achieve high rotation, exceeding 0.15 rad, and an overstrength factor equal to 1.5. Failure involved included web buckling at very high rotation. The T-EBF displayed a very good, non-replaceable ductile link. The experiments were followed by an isotropic kinematic-combined hardening model in the finite element analyses (FEA). The FEA analysis is developed to predict the effect of web opening configuration on the local section stresses and strains and global characteristics of the frame. FEA exhibits good agreement with the experimental results and can capture the inelastic buckling behavior of the sections. The link configuration parameters of the T-EBF were studied extensively on a W18x76 shear link subjected to the 2016 AISC seismic design provisions loading protocol (ANSI/AISC 341-16, 2016). The parametric study also included the performance of a range of wide flange sections. The analysis shows that the reduced web section has effect on the plastic strain in which low plastic strain observed near ends and connections and high at the center of the web. Results also demonstrate that if the shear link is appropriately sized with web opening and intermediate web stiffeners provided, an excellent shear link with high ductility under cyclic loads can be obtained. Changing the configuration of the opening cutout also had a significant effect on reducing the transition zone cracks.
Author: John P. Evans Publisher: ISBN: Category : Languages : en Pages : 76
Book Description
Eccentric braced frames have been a topic of research in seismic design over the past twenty years. The idea of eccentric bracing is a relatively new method used in practice to satisfy seismic design requirements. They have been proven to give reliable results in tests using simulated earthquake events, as well as provide an economical advantage over other framing methods. Two one-story eccentric braced frame models were created using computer generated finite element analysis. The example chosen for this study are discussed further. The maximum shear stress distribution in the link beam of the frame, using finite element analysis, will be investigated herein. The results of the shear stress produced gives insight to shear forces developed in the link beam of eccentric braced frames. The results of shear forces produced are compared with those calculated by structural engineers using commonly used hand calculated equations.
Author: Dmitry Volynkin Publisher: ISBN: Category : Columns, Iron and steel Languages : en Pages : 174
Book Description
Eccentrically Braced Frames (EBFs) are a widely used seismic resisting structural steel system. Since their inception in the late 1970s, they have been a viable option with an available stiffness that is between simple braced systems and moment resisting systems. A similar concept, the linked column frame (LCF), uses shear links between two closely spaced columns. In both cases, the key component is the active link or the shear link, and this component is the objective of this study. The performance of high rise EBF buildings in the 2010 and 2011 Christchurch earthquakes was beyond that which was expected, especially considering the very high accelerations recorded. As the concrete high-rises were torn down, two EBF buildings remained standing and only required some structural repair. These events prompted a renewed interest in bolted shear links, as well as their performance. While some research into replaceable shear links had already been done (Mansour, 2011), the objectives of this study were to improve on the shear link itself, with the consideration that links built in the future are likely to be bolted. The main components of this study were to: 1. Reduce or eliminate the requirements for intermediate web stiffeners, as they were suspected of being detrimental to performance. Furthermore, any reduction in stiffening requirements is a direct fabrication cost saving. Links with low web aspect ratios were found to achieve exceptional ductilities when no stiffeners were included, prompting new design equations. 2. Ensure that the stresses in the ends of links are adequately transferred into the endplates without causing fractures. Although most of the experimental links had web doubler plates included, four had varied lengths of such doubler plates from 0.0 in. to 8.0 in. The link without any doubler plates performed to a similar level to its peers, and thus it is likely that links with quality end details may not need web doubler plates at all. 3. Evaluate the performance of a link with double sided stiffeners without the use of web welds, as opposed to conventional single sided, welded stiffeners. This link performed well, and web-weld-less double sided stiffeners may be an economical alternative to conventional stiffeners for deeper sections of links. 4. Evaluate the performance of a link with thin endplates that are made efficient with the use of gusset plates. This link performed to an acceptable level and provides evidence for a cost effective alternative to thick endplates, especially considering the high overstrength end moments in links, typically requiring 16-bolt connections. 5. Examine the potential use of an alternative EBF arrangement where the collector beam is over sized, and the link section is formed by cutting out parts of the beam's web. After running a series of finite element models each with a unique variation, a number of approximate design rules were derived such that future research could develop this idea further experimentally. 6. Ensure that during testing, the secondary elements (members that are not the shear link), do not yield and are not close to yielding. None of the instrumented elements experienced any unexpected yielding, however the concerns for high stresses in the collector beam panel zone during design were warranted. The use of an existing New Zealand design equation is recommended as an extra check for design codes worldwide. The above objectives were mainly conducted experimentally, except: the data set for item 1 was greatly expanded through the use of a calibrated numerical model which was then used in an extensive parametric study; item 5 was purely finite element based; and, a small parametric study was included for item 3 in an attempt to expand on the trends found there.
Author: Stephen P. Wilkinson Publisher: CRC Press ISBN: 1315647133 Category : Nature Languages : en Pages : 290
Book Description
Sustainable Buildings and Structures collects the contributions presented at the 1st International Conference on Sustainable Buildings and Structures (Suzhou, China, 29 October-1 November 2016). The book aims to share thoughts and ideas on sustainable approaches to urban planning, engineering design and construction. The topics discussed include:-
Author: Sheila Belayutham Publisher: Springer Nature ISBN: 981167924X Category : Technology & Engineering Languages : en Pages : 1515
Book Description
This book compiles papers presented during the 5th International Conference on Sustainable Civil Engineering Structures and Construction Materials (SCESCM) held virtually in December 2020. This is the fifth edition of this conference series; the theme for the 5th SCESCM is “Transforming the World, Foster the Sustainable Development Goals (SDGs),” and it focuses on various issues, novel findings, as well as developments in the area of civil and infrastructure, conforming to the SDGs. This book caters to postgraduate students, researchers, and practitioners involved in advocating and embedding sustainability in various phases of design, construction and maintenance of civil engineering structures and infrastructure facilities.
Author: Yucel Alp
Author: Yucel Alp
Author: 
Author: John P. Evans
Author: Dmitry Volynkin
Author: 
Author: Stephen P. Wilkinson
Author: Keith D. Hjelmstad
Author: Paul William Richards
Author: James O. Malley
Author: Sheila Belayutham