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32 records – page 2 of 4.

Feasibility of Cross-Laminated Timber Cores for the UBC Tall Wood Building

https://research.thinkwood.com/en/permalink/catalogue1905
Year of Publication
2018
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Shafts and Chases
Author
Connolly, Thomas
Moudgil, Manu
Loss, Christiano
Iqbal, Asif
Tannert, Thomas
Year of Publication
2018
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Shafts and Chases
Topic
Design and Systems
Keywords
Brock Commons
Hybrid
Environmental Footprint
Seismic Performance
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 20-23,2018. Seoul, Republic of Korea
Summary
The innovation in tall mass-timber buildings is illustrated by the Brock Commons student residence at the University of British Columbia also known as the UBC Tall Wood Building. It is amongst the world’s tallest timber hybrid building with 18 stories and 53 meters’ height. The building has 17 stories of mass-timber superstructure resting on a concrete podium with two concrete cores that act as a lateral force resisting system for earthquake and wind forces. Construction of the mass-timber superstructure took ten weeks whereas the concrete cores were built in fourteen weeks. There could have been a substantial reduction in the project timeline leading to cost savings, as well as a further reduction of environmental footprint if mass-timber had been used for the cores. The objective of this work was to evaluate the possibility to design the UBC Tall Wood Building using mass-timber cores. A validated numerical model was used to study the feasibility of replacing the concrete cores by cores made of Cross Laminated Timber (CLT). The results presented herein show that, with adjustments in the configuration, the structure can meet the seismic performance criteria as per the Canadian code with CLT cores.
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Fragility-based methodology for evaluating the time-dependent seismic performance of post-tensioned timber frames

https://research.thinkwood.com/en/permalink/catalogue2871
Year of Publication
2020
Topic
Seismic
Application
Frames
Author
Granello, Gabriele
Palermo, Alessandro
Pampanin, Stefano
Organization
University of Canterbury
ETH Zurich
Sapienza University of Rome
Publisher
SAGE Journals
Year of Publication
2020
Format
Journal Article
Application
Frames
Topic
Seismic
Keywords
Pres-Lam
Post-Tensioned Timber
Fragility Analysis
Seismic Performance
Research Status
Complete
Series
Earthquake Spectra
Summary
Since 2010, the construction of post-tensioned wooden buildings (Pres-Lam) has been growing rapidly worldwide. Pres-Lam technology combines unbonded post-tensioning tendons and supplemental damping devices to provide moment capacity to beam–column, wall–foundation, or column–foundation connections. In low seismic areas, designers may choose not to provide additional damping, relying only on the post-tensioning contribution. However, post-tensioning decreases over time due to creep phenomena arising in compressed timber members. As a consequence, there is a reduction of the clamping forces between the elements. This reduction affects the seismic response of Pres-Lam buildings in the case of low- and high-intensity earthquakes. Therefore, understanding and accounting for the post-tensioning losses and their uncertainty are paramount for a robust assessment of the safety of Pres-Lam constructions. So far, however, there have been no comprehensive studies which tackle the overall seismic performance of such systems in the presence of time-varying post-tension losses and the associated uncertainty. This study tackles this research gap by introducing a comprehensive seismic evaluation of Pres-Lam systems based on time-dependent fragility curves. The proposed fragility analysis is specifically designed to account systematically for time-varying post-tension losses and the related uncertainty. The method is applied to two case studies, designed, respectively, with and without supplemental damping devices. In terms of structural performance, results show that the use of additional dissipaters mitigates the effect of post-tensioning loss for earthquakes of high intensity. Conversely, performance under low-intensity earthquakes is strongly dependent on the post-tensioning value, as the reduction of stiffness due to the anticipated rocking motion activation would lead to damage to non-structural elements.
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In-Plane Strength and Stiffness of Cross-Laminated Timber Shear Walls

https://research.thinkwood.com/en/permalink/catalogue2117
Year of Publication
2018
Topic
Design and Systems
Connections
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Walls
Floors
Author
Shahnewaz, Md
Alam, Shahria
Tannert, Thomas
Publisher
MDPI
Year of Publication
2018
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Walls
Floors
Topic
Design and Systems
Connections
Keywords
Finite Element Analysis
Connections
Ductility
Parametric Study
Seismic Performance
Research Status
Complete
Series
Buildings
Summary
The research presented herein investigated the in-plane performance of cross-laminated timber (CLT) shear walls for platform-type buildings under lateral loading. Finite element models of CLT connections (i.e., brackets, hold-downs and self-tapping screws) were developed in OpenSees and calibrated against experimental tests to represent the connections’ hysteresis behaviour under cyclic tension and shear loading. The results were incorporated into models of CLT single and coupled shear walls. The results in terms of peak displacement, peak load and energy dissipation were in good agreement when compared to full-scale shear wall tests. Subsequently, a parametric study of 56 single and 40 coupled CLT shear walls was conducted with varying numbers and types of connectors (wall-to-floor and wall-to-wall) for evaluating their seismic performance. It was found that the strength, stiffness and energy dissipation of the single and coupled CLT shear walls increased with an increase in the number of connectors. Single shear walls with hold-downs and brackets performed better under seismic loading compared to walls with brackets only. Similarly, coupled shear walls with four hold-downs performed better compared to walls with two hold-downs. Finally, ductility of coupled shear walls was found to be 31% higher compared to that of single shear walls. The findings from this research are useful for engineers to efficiently design CLT shear walls in platform-type construction.
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Lateral Load Resistance of Cross-Laminated Wood Panels

https://research.thinkwood.com/en/permalink/catalogue2150
Year of Publication
2010
Topic
Connections
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Walls
Author
Popovski, Marjan
Schneider, Johannes
Schweinsteiger, Matthias
Year of Publication
2010
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Walls
Topic
Connections
Seismic
Keywords
Quasi-Static Tests
Seismic Performance
Screws
Nails
Steel Brackets
Timber Rivets
Conference
World Conference on Timber Engineering
Research Status
Complete
Summary
In this paper, some of the results are presented from a series of quasi-static tests on CLT wall panels conducted at FPInnovation-Forintek in Vancouver, BC. CLT wall panels with various configurations and connection details were tested. Wall configurations included single panel walls with three different aspect ratios, multi-panel walls with step joints and different types of screws to connect them, as well as two-storey wall assemblies. Connections for securing the walls to the foundation included: off-the-shelf steel brackets with annular ring nails, spiral nails, and screws; combination of steel brackets and hold-downs; diagonally placed long screws; and custom made brackets with timber rivets. Results showed that CLT walls can have adequate seismic performance when nails or screws are used with the steel brackets. Use of hold-downs with nails on each end of the wall improves its seismic performance. Use of diagonally placed long screws to connect the CLT walls to the floor below is not recommended in high seismic zones due to less ductile wall behaviour. Use of step joints in longer walls can be an effective solution not only to reduce the wall stiffness and thus reduce the seismic input load, but also to improve the wall deformation capabilities. Timber rivets in smaller groups with custom made brackets were found to be effective connectors for CLT wall panels. Further research in this field is needed to further clarify the use of timber rivets in CLT.
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Nonlinear Static Seismic Response of a Building Equipped with Hybrid Cross-Laminated Timber Floor Diaphragms and Concentric X-Braced Steel Frames

https://research.thinkwood.com/en/permalink/catalogue2761
Year of Publication
2021
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Steel-Timber Composite
Application
Floors
Author
Roncari, Andrea
Gobbi, Filippo
Loss, Cristiano
Organization
University of British Columbia
University of Trento
Publisher
MDPI
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Steel-Timber Composite
Application
Floors
Topic
Seismic
Keywords
Seismic Design
Hybrid Structures
Lateral Resistance
Semi-rigid Diaphragms
Load Distribution
Seismic Performance
Pushover Analysis
Nonlinear Static Analysis
Finite Element Model
Research Status
Complete
Series
Buildings
Summary
Simplified seismic design procedures mostly recommend the adoption of rigid floor diaphragms when forming a building’s lateral force-resisting structural system. While rigid behavior is compatible with many reinforced concrete or composite steel-concrete floor systems, the intrinsic stiffness properties of wood and ductile timber connections of timber floor slabs typically make reaching a such comparable in-plane response difficult. Codes or standards in North America widely cover wood-frame construction, with provisions given for both rigid and flexible floor diaphragms designs. Instead, research is ongoing for emerging cross-laminated-timber (CLT) and hybrid CLT-based technologies, with seismic design codification still currently limited. This paper deals with a steel-CLT-based hybrid structure built by assembling braced steel frames with CLT-steel composite floors. Preliminary investigation on the performance of a 3-story building under seismic loads is presented, with particular attention to the influence of in-plane timber diaphragms flexibility on the force distribution and lateral deformation at each story. The building complies with the Italian Building Code damage limit state and ultimate limit state design requirements by considering a moderate seismic hazard scenario. Nonlinear static analyses are performed adopting a finite-element model calibrated based on experimental data. The CLT-steel composite floor in-plane deformability shows mitigated effects on the load distribution into the bracing systems compared to the ideal rigid behavior. On the other hand, the lateral deformation always rises at least 17% and 21% on average, independently of the story and load distribution along the building’s height.
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North American Research Needs Assesment for Mass Timber

https://research.thinkwood.com/en/permalink/catalogue3222
Year of Publication
2021
Topic
General Information
Material
CLT (Cross-Laminated Timber)
Author
Zelinka, Samuel
Williamson, Tom
Martinson, Karen
Ritter, Michael A.
Organization
Forest Products Laboratory
Year of Publication
2021
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
General Information
Keywords
Mass Timber
North America
Seismic Performance
Fire Performance
Conference
World Conference on Timber Engineering
Research Status
Complete
Summary
The 2nd Mass Timber Research Needs Assessment Workshop was held on November 13-14, 2018 at the US Forest Service, Forest Products Laboratory (FPL). The purpose of the workshop was to convene a group of experts on cross laminated timber and mass timber to develop a list of prioritized research needs for the North American mass timber industry. The workshop had over 100 attendees including design professionals, academics, industry leaders, and government employees. The attendees generated a list of over 117 research needs. After the workshop, the list of 117 research needs was prioritized through the use of an online survey. This paper presents highlights of the top research needs generated at the 2nd Mass Timber Research Needs Assessment Meeting.
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Numerical Study of Alternative Seismic-Resisting Systems for CLT Buildings

https://research.thinkwood.com/en/permalink/catalogue2176
Year of Publication
2018
Topic
Connections
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Walls
Shear Walls
Author
Loss, Cristiano
Pacchioli, Stefano
Polastri, Andrea
Casagrande, Daniele
Pozza, Luca
Smith, Ian
Publisher
MDPI
Year of Publication
2018
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Walls
Shear Walls
Topic
Connections
Design and Systems
Keywords
Seismic Performance
Superstructures
Research Status
Complete
Series
Buildings
Summary
Changes to building codes that enable use of materials such as cross-laminated timber (CLT) in mid- and high-rise construction are facilitating sustainable urban development in various parts of the world. Keys to this are the transition to multi-performance-based design approaches along with fewer limitations on heights or the number of storeys in superstructures constructed from combustible materials. Architects and engineers have increased freedom to apply new design and construction concepts and methods, as well as to combine timber with other structural materials. They also have started to develop wall arrangements that optimise interior space layouts and take advantage of the unique characteristics of CLT. This paper discusses the seismic response of multi-story buildings braced with a CLT core and perimeter shear walls anchored to foundations and floor platforms using modern high-capacity angle brackets and hold-downs, or X-Rad connectors. Linear dynamic finite element (FE) models of seismic responses of superstructures of various heights are presented, based on experimentally determined characteristics of wall anchor connections. Particular attention is given to fundamental vibration periods, base shear and uplift forces on walls, as well as inter-story drift. Discussion of FE model results focuses on structural engineering implications and advantages of using CLT to create shear walls, with emphasis on how choice of wall anchoring connections impacts the possible number of storeys and configurations of superstructures. Employing CLT shear walls with X-Rad or other types of high capacity anchoring connections makes possible the creation of building superstructures having eight and potentially more storeys even in high seismicity regions. However, it is important to emphasise that proper selection of suitable arrangements of shear walls for CLT buildings depends on accurate representation of the semi-rigid behaviors of anchoring connections. The linear dynamic analyses presented here demonstrates the need during engineering seismic design practices to avoid use of FE or other design models which do not explicitly incorporate connection flexibilities while estimating parameters like fundamental periods, base shear and uplift forces, as well as inter-story drift.
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Performance Evaluation of Multi-Storey Cross-Laminated Timber Structures Under Different Earthquake Hazard Levels

https://research.thinkwood.com/en/permalink/catalogue1384
Year of Publication
2018
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Shear Walls
Author
Sun, Xiaofeng
He, Minjuan
Li, Zheng
Shu, Zhan
Publisher
Springer Japan
Year of Publication
2018
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Shear Walls
Topic
Design and Systems
Keywords
Equivalent Static Force Procedure
Multi-Storey
Seismic Performance
Lateral Load Resisting System
Inter-Story Drift
Pinching4 Model
Numerical Model
Probability of Non-Exceedance
Empirical Cumulative Distribution Functions
Research Status
Complete
Series
Journal of Wood Science
Summary
The inter-storey drift limitations are meaningful reference values for structural seismic performance evaluation. This paper presents an analytical investigation into the seismic performance of multi-storey cross-laminated timber (CLT) structures to obtain the drift limitations under different earthquake hazard levels reasonably. The Pinching4 model was used to simulate the nonlinear mechanical behavior of three types of connections used in CLT structures, and a numerical model was further developed to capture the lateral load-resisting properties of CLT shear walls. Moreover, three benchmark multi-storey CLT apartment buildings were designed using the Equivalent Static Force Procedure according to National Building Code of Canada (NBCC), and simplified structural models were developed for these buildings. Depending on the results from numerous time-history dynamic analyses, the empirical cumulative distribution functions (CDFs) of the maximum inter-storey drifts were constructed for the three benchmark buildings. The probability of non-exceedance (PNE) of inter-storey drift thresholds under different earthquake hazard levels was proposed and validated. It is recommended that for low-rise CLT buildings within three stories, values of 0.30%, 0.75%, and 1.40% can be considered as the drift limitations for frequent, medium, and rare seismic hazard levels, respectively. For mid-rise or high-rise buildings without three stories, 0.25%, 0.70%, and 1.30% can be considered as drift limitations.
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Progress on the Development of Strong Seismic Resilient Tall CLT Buildings in the Pacific Northwest

https://research.thinkwood.com/en/permalink/catalogue1881
Year of Publication
2014
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Pei, Shiling
Berman, Jeffrey
Dolan, Daniel
van de Lindt, John
Ricles, James
Sause, Richard
Blomgren, Hans-Erik
Popovski, Marjan
Rammer, Douglas
Year of Publication
2014
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Seismic
Keywords
Tall Wood
Seismic Performance
Resilience-Based Seismic Design
Conference
World Conference on Timber Engineering
Research Status
Complete
Summary
As urban densification occurs in U.S. regions of high seismicity, there is a natural demand for seismically resilient tall buildings that are reliable, economically viable, and can be rapidly constructed. In urban regions on the west coast of the U.S., specifically the Pacific Northwest, there is significant interest in utilizing CLT in 8-20 story residential and commercial buildings due to its appeal as a potential locally sourced, sustainable and economically competitive building material. In this study, results from a multi-disciplinary discussion on the feasibility and challenges in enabling tall CLT building for the U.S. market were summarized. A three-tiered seismic performance expectations that can be implemented for tall CLT buildings was proposed to encourage the adoption of the system at a practical level. A road map for building tall CLT building in the U.S. was developed, together with three innovative conceptual CLT systems that can help reaching resiliency goals. This study is part of an on-going multi-institution research project funded by National Science Foundation.
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Research Needs Assessment for the Mass Timber Industry: Proceedings of the 2nd North American Mass Timber Research Needs Workshop

https://research.thinkwood.com/en/permalink/catalogue2164
Year of Publication
2019
Topic
General Information
Material
CLT (Cross-Laminated Timber)
DLT (Dowel Laminated Timber)
NLT (Nail-Laminated Timber)
Glulam (Glue-Laminated Timber)
Timber-Concrete Composite
Application
Shear Walls
Walls
Wood Building Systems
Floors
Columns
Bridges and Spans
Author
Zelinka, Samuel
Williamson, Tom
Martinson, Karen
Ritter, Michael
Organization
Forest Products Laboratory
Year of Publication
2019
Format
Report
Material
CLT (Cross-Laminated Timber)
DLT (Dowel Laminated Timber)
NLT (Nail-Laminated Timber)
Glulam (Glue-Laminated Timber)
Timber-Concrete Composite
Application
Shear Walls
Walls
Wood Building Systems
Floors
Columns
Bridges and Spans
Topic
General Information
Keywords
Mass Timber
North America
Research Needs
Research Priorities
Seismic Performance
Fire Performance
Research Status
Complete
Summary
The 2nd Mass Timber Research Needs Assessment was held on November 13–14, 2018, at the USDA Forest Service, Forest Products Laboratory (FPL). The workshop was co-sponsored by FPL, WoodWorks, and the U.S. Endowment for Forestry and Communities. The purpose of the workshop was to gather a diverse group of people with expertise in mass timber, in particular cross-laminated timber, to discuss and prioritize research needed to move the mass timber industry forward in North America. The workshop was attended by more than 100 design professionals, researchers, manufacturers, industry leaders, and government employees. The meeting resulted in a list of 117 research needs. Following the meeting, the list of research needs was prioritized through an online survey. This report presents the prioritized research needs of the mass timber industry in North America. Also included in the appendixes are the formal minutes of the workshop, a list of participants, and the original scribe notes.
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32 records – page 2 of 4.