Mass Timber Frame with Mass Timber Buckling Restrained Braces for Seismically Resilient Mass Timber Buildings PDF Download
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Author: Emily Rose Williamson Publisher: ISBN: Category : Buckling (Mechanics) Languages : en Pages : 0
Book Description
As mass timber continues to increase in popularity as a primary structural material, it is desirable to develop efficient, ductile lateral force resisting systems (LFRS). A timber buckling restrained brace (TBRB) is presented as a possible solution for creating seismically resilient timber buildings. Like conventional buckling restrained braces (BRB), the TBRB utilizes a steel yielding core, but the restraining element is mass ply panel (MPP) blocks instead of the conventional concrete-filled steel tube. To understand the failure modes and moment-rotation relationship of the beamcolumn connections, six mass ply lam (MPL) beam-column connections were tested with various dowel layouts under monotonic and cyclic loading protocols. The joints achieved rotations of 0.11 radians (6.3 degrees) without visible external connection damage. Next, two sets of testing series were adopted for testing the TBRB frames (TBRBF). In the first testing series, four TBRBF tests were completed with varying levels of axial force in the columns. Bare frame tests were also completed to observe the stiffness degradation throughout the testing series. The TBRBFs achieved a story drift ratio exceeding 2.8% before TBRB failure. The primary failure mode was splitting of the casing caused by weak-axis bucking of the core near the ends of the yielding zone. In the second TBRBF testing series, three TBRBs were tested. Two of the three TBRBs were enhanced with carbon fiber wrap at the ends of the casing to avoid the premature failure of the casing observed during the first testing series. The carbon fiber wrap allowed the TBRBF to achieve 4.5% drift ratio and changed the failure mode of the TBRB to tensile fracture of the steel core. Finally, the bare timber frame was tested up to 8.0% drift ratio. Finally, numerical models for the TBRB and beam-column connections were developed and combined into a single-story frame model. The model was validated by the TBRBF experimental results. After validation, the model was extrapolated into an eight-story TBRBF. The model was studied under pushover, cyclic, and earthquake loads. Moreover, the results of the model combined with the experimental results present the TBRBF as a feasible LFRS for resilient timber buildings.
Author: Emily Rose Williamson Publisher: ISBN: Category : Buckling (Mechanics) Languages : en Pages : 0
Book Description
As mass timber continues to increase in popularity as a primary structural material, it is desirable to develop efficient, ductile lateral force resisting systems (LFRS). A timber buckling restrained brace (TBRB) is presented as a possible solution for creating seismically resilient timber buildings. Like conventional buckling restrained braces (BRB), the TBRB utilizes a steel yielding core, but the restraining element is mass ply panel (MPP) blocks instead of the conventional concrete-filled steel tube. To understand the failure modes and moment-rotation relationship of the beamcolumn connections, six mass ply lam (MPL) beam-column connections were tested with various dowel layouts under monotonic and cyclic loading protocols. The joints achieved rotations of 0.11 radians (6.3 degrees) without visible external connection damage. Next, two sets of testing series were adopted for testing the TBRB frames (TBRBF). In the first testing series, four TBRBF tests were completed with varying levels of axial force in the columns. Bare frame tests were also completed to observe the stiffness degradation throughout the testing series. The TBRBFs achieved a story drift ratio exceeding 2.8% before TBRB failure. The primary failure mode was splitting of the casing caused by weak-axis bucking of the core near the ends of the yielding zone. In the second TBRBF testing series, three TBRBs were tested. Two of the three TBRBs were enhanced with carbon fiber wrap at the ends of the casing to avoid the premature failure of the casing observed during the first testing series. The carbon fiber wrap allowed the TBRBF to achieve 4.5% drift ratio and changed the failure mode of the TBRB to tensile fracture of the steel core. Finally, the bare timber frame was tested up to 8.0% drift ratio. Finally, numerical models for the TBRB and beam-column connections were developed and combined into a single-story frame model. The model was validated by the TBRBF experimental results. After validation, the model was extrapolated into an eight-story TBRBF. The model was studied under pushover, cyclic, and earthquake loads. Moreover, the results of the model combined with the experimental results present the TBRBF as a feasible LFRS for resilient timber buildings.
Author: Fokruddin Ahmad Publisher: ISBN: Category : Earthquake engineering Languages : en Pages : 0
Book Description
The use of Buckling Restrained Brace Frames (BRBFs) has been increasing in recent decades due to their ability to provide superior seismic performance and enhance the resilience of buildings against earthquakes. However, not many studies have extensively and thoroughly investigated the response and resiliency of prescriptively designed BRBF buildings to varying types of earthquake hazards. This study fills that research gap by investigating the seismic performance of two code-designed BRBFs prototype buildings subjected to far-field, near field with pulse and without pulse, and long-duration ground motion sets. The first phase of the study investigated the seismic resiliency of the prescriptively designed BRBF buildings and compared them to identical prototypes designed with mass timber PT-CLT rocking walls using the FEMA P-58 methodology to compare seismic losses. The seismic loss investigation was part of a larger study evaluating the two types of structural systems using multiple criteria decision analysis across four performance categories of seismic resiliency, global warming potential, superstructure cost, and durability. The global warming potential and superstructure cost estimate was completed by others, but this study completed the seismic resiliency assessment and multiple criteria decision analysis.The second phase of this dissertation work analyzed the structural response of the two BRBF prototype buildings across four sets of ground motions representing different hazard levels in Seattle, WA. The two prototype buildings were modeled in 3D using OpenSeesPy to understand the effect of different ground motion types on the structural responses. The analysis results showed that near-field motions increase the deformation demands, such as inter-story drift and maximum ductility in the pulse direction. Though BRBFs are not a self-centering systems, only the upper two floors of the mid-rise building experienced residual drift higher than 0.2%, which is the threshold for expecting minor repair and structural realignment. None of the stories had residual inter-story drift exceeding 0.5% drift for any motion sets. Overall, the code minimum based BRBF buildings showed excellent performance across all the different hazard types. However, the one caveat of this analysis was that long-duration motions had significantly higher cumulative ductility demand than other motion sets.Therefore, the final phase of this dissertation works further investigated the cumulative deformation demand on BRBF braces under long-duration motions. It is important to verify the ductility of the braces through analysis or testing because they act as the primary structural fuse to dissipate the earthquake energy. The final study compared different loading protocols from different countries to the nonlinear modeling results of long-duration motions. It was determined that the long duration motions had over 80% probability of exceeding the current AISC 341 required testing protocol. To rectify these issues, a new loading protocol appropriate for long-duration earthquakes was proposed that accounts for the increased plastic deformation demand and matches the cyclic content of the nonlinear dynamic analyses.In conclusion, these studies have demonstrated that prescriptively designed BRBFs that meet code minimum requirements are a high performing lateral force resisting system to a range of earthquake hazards. They have excellent seismic resiliency, even when not optimized during design through nonlinear time history analysis, as is common in performance-based earthquake engineering. Additionally, the code-designed BRBF buildings were not predicted to have high residual inter-story drifts, which means they are highly likely to be repairable with minor adjustments and re-alignment. However, it was identified that long-duration earthquakes will increase the ductility demand on the braces significantly compared to far-field and near-field earthquakes and that current minimum testing requirements do not account for this increase. A new protocol was proposed to rectify this one challenge with BRBFs.
Author: Douglas R. Rammer Publisher: ISBN: Category : Buckling (Mechanics) Languages : en Pages : 2
Book Description
Buckling-restrained braced frames (BRBFs) are one of the newer types of seismic-force-resisting systems used in modern building designs. In BRBFs, the primary source of ductility is the axial yielding of the buckling-restrained brace (BRB) cores, and BRBFs have improved ductility in comparison to ordinary or special braced frames. BRBs are incorporated into frame structures to dissipate energy or prevent damage to the surrounding structures. Frame systems employing this type of BRBs have demonstrated improved ductility and are currently an approved seismic-force-resisting system in the ASCE 7-10 code document (ASCE 2010).
Author: Susan Jones Publisher: ISBN: 9781939621955 Category : Building, Wooden Languages : en Pages : 0
Book Description
Mass Timber / Design and Research presents new research and design work with Mass Timber, a new construction technology, well-known in Europe, but relatively unfamiliar in the United States. Leading the Mass Timber design dialogue in the US, the author, Susan Jones, an architect in Seattle, Washington, has been pioneering the new, innovative use of wood over the past six years, since she built her own family's house from cross-laminated timber in 2015 in a neighborhood in Seattle. The book presents her Seattle firm, her family, and her University of Washington students' years of research and design. Opening with the story of three generations of her family's own sustainable forest practices, the book presents research into Pacific Northwest forestry, timber and Cross-Laminated Timber manufacturing practices, to carbon analysis and carbon comparisons between standard building construction assemblies and technologies; and concludes with the design of model buildings both designed and built by her firm, atelierjones and her University of Washington students: including a single-family house, a church, schools, multi-family housing, and a twelve-story Tall Timber Wood Innovation tower on the University of Washington campus in Seattle.
Author: International Code Council Publisher: ISBN: 9781265164348 Category : Construction industry Languages : en Pages : 0
Book Description
"Developed by ICC and American Wood Council, this first edition provides an overview of requirements for mass timber construction as found in the 2021 International Building Code℗ʼ (IBC℗ʼ). The document reviews the 2015 IBC's recognition of cross-laminated timber (CLT), the reorganization of heavy timber provisions in the 2018 IBC, followed by the historic changes in the 2021 IBC and International Fire Code℗ʼ (IFC℗ʼ) for tall mass timber construction. The 2021 IBC and IFC include important changes in material technologies and their expanded use as proposed by the ICC Ad Hoc Committee on Tall Wood Buildings. Three new types of construction (Types IV-A, IV-B and IV-C) defined and included in the 2021 codes allow the use of mass timber for buildings of taller heights, more stories above grade, and greater allowable areas compared to existing provisions for heavy timber buildings." -- Publisher's description.
Author: Joan Ramon Casas Publisher: CRC Press ISBN: 1000798771 Category : Technology & Engineering Languages : en Pages : 5491
Book Description
Bridge Safety, Maintenance, Management, Life-Cycle, Resilience and Sustainability contains lectures and papers presented at the Eleventh International Conference on Bridge Maintenance, Safety and Management (IABMAS 2022, Barcelona, Spain, 11–15 July, 2022). This e-book contains the full papers of 322 contributions presented at IABMAS 2022, including the T.Y. Lin Lecture, 4 Keynote Lectures, and 317 technical papers from 36 countries all around the world. The contributions deal with the state-of-the-art as well as emerging concepts and innovative applications related to the main aspects of safety, maintenance, management, life-cycle, resilience, sustainability and technological innovations of bridges. Major topics include: advanced bridge design, construction and maintenance approaches, safety, reliability and risk evaluation, life-cycle management, life-cycle, resilience, sustainability, standardization, analytical models, bridge management systems, service life prediction, structural health monitoring, non-destructive testing and field testing, robustness and redundancy, durability enhancement, repair and rehabilitation, fatigue and corrosion, extreme loads, needs of bridge owners, whole life costing and investment for the future, financial planning and application of information and computer technology, big data analysis and artificial intelligence for bridges, among others. This volume provides both an up-to-date overview of the field of bridge engineering and significant contributions to the process of making more rational decisions on bridge safety, maintenance, management, life-cycle, resilience and sustainability of bridges for the purpose of enhancing the welfare of society. The volume serves as a valuable reference to all concerned with and/or involved in bridge structure and infrastructure systems, including students, researchers and practitioners from all areas of bridge engineering.
Author: Yue Xiao Publisher: ISBN: Category : Buckling (Mechanics) Languages : en Pages : 213
Book Description
A series of earthquakes occurred in Christchurch that demonstrate the need for developing low damage economic multi-storey structures. Post tensioned timber was proposed to be used on constructing such multi-storey framed structures with additional seismic resisting system to reduce the damage on structure. Buckling Restrained Braces (BRB) as a well-designed, widely used seismic resisting system used on multi-storey steel structures has been modified into a timber steel BRB for artistically fitting into the proposed structure. This research project focuses on designing and testing a feasible Timber Steel BRB that can meet New Zealand design requirements. A detailed design procedure has been developed based on a case study in a 7 story office building located in Christchurch. Based on the case study, the design load and minimum displacement requirement for one full scale BRB is calculated as 668kN and 25mm. After preliminary Finite Element Modelling analysis and required strength calculations on performance of yielding core with different cross-section detail (cruciform, H-section, flat section and I-section). An I-section yielding core with a flange width to web height ratio of 0.42 is selected due to the lower requirement in restraining strength. With further design, the timber outer casing is separated into 4 pieces and glued together to encase the I-section shape. Due to the limitations in the testing machine, three 1:2.5 scale Timber-Steel BRBs are constructed and tested. The experimental tests show stable hysteresis loops which suggest good performance of the proposed Timber-Steel BRB and two test specimens with perpendicular to grain reinforcement are able to deform to the minimum required deformation which indicates this design is feasible to use in New Zealand. The results also indicate the timber reinforcement along the brace in both yielding core axes and the debonding agent for glue bound timber steel BRB are necessary.
Author: Antony Wood Publisher: ISBN: 9780939493814 Category : Languages : en Pages : 0
Book Description
As a natural building material, mass timber provides extraordinary benefits. Through the growth of trees, its production sequesters rather than emits carbon dioxide, and thus helps counteract climate change. Fused into mass timber panels, beams, and columns, its relative light weight and great strength make it a competitive choice for building tall, reducing on-site assembly time, construction personnel, and associated costs, while offering the precision that comes with prefabrication. The aesthetic appeal of exposed timber drives psychological and physiological well-being, which can also translate into lease and sale premiums. There are challenges of course, with many national and local fire codes heavily restricting the use of timber in the structure and façades of high-rise buildings. But as more use cases and test results become available, attitudes and codes are adapting.This publication, the outcome of a grant from the USDA Forest Service and Binational Softwood Lumber Council, is a key step forward in increasing understanding of this exciting material. Through twelve detailed, richly illustrated case studies-as well as key topical considerations contributed by the leading experts in timber construction-Tall Timber is the definitive guide for all practitioners involved in the development, design, and operation of tall buildings. The reader will gain a greater understanding of this ancient, newly-reborn material, with its vast potential to build greener, more sustainable cities. It is a companion to the Tall Timber Center, a comprehensive online resource at talltimbercenter.com.
Author: Emily Rose Williamson
Author: Emily Rose Williamson
Author: Fokruddin Ahmad
Author: Douglas R. Rammer
Author: Susan Jones
Author: Azer Kasimzade
Author: International Code Council
Author: Joan Ramon Casas
Author: J. Cole Schulze
Author: Yue Xiao
Author: Antony Wood