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Achieving Sustainable Urban Buildings with Seismically Resilient Mass Timber Core Wall and Floor System

https://research.thinkwood.com/en/permalink/catalogue2802
Topic
Design and Systems
Seismic
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Cores
Walls
Floors
Wood Building Systems
Organization
Portland State University
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Cores
Walls
Floors
Wood Building Systems
Topic
Design and Systems
Seismic
Keywords
Hold-Down
Seismic Performance
Core Walls
Parametric Analysis
Deformation Capacity
Overstrength
Mid-Rise
High-Rise
Tall Wood Buildings
Research Status
In Progress
Notes
Project contact is Peter Dusicka at Portland State University
Summary
The urgency in increasing growth in densely populated urban areas, reducing the carbon footprint of new buildings, and targeting rapid return to occupancy following disastrous earthquakes has created a need to reexamine the structural systems of mid- to high-rise buildings. To address these sustainability and seismic resiliency needs, the objective of this research is to enable an all-timber material system in a way that will include architectural as well as structural considerations. Utilization of mass timber is societally important in providing buildings that store, instead of generate, carbon and increase the economic opportunity for depressed timber-producing regions of the country. This research will focus on buildings with core walls because those building types are some of the most common for contemporary urban mid- to high-rise construction. The open floor layout will allow for commercial and mixed-use occupancies, but also will contain significant technical knowledge gaps hindering their implementation with mass timber. The research plan has been formulated to fill these gaps by: (1) developing suitable mid- to high-rise archetypes with input from multiple stakeholders, (2) conducting parametric system-level seismic performance investigations, (3) developing new critical components, (4) validating the performance with large-scale experimentation, and (5) bridging the industry information gaps by incorporating teaching modules within an existing educational and outreach framework. Situated in the heart of a timber-producing region, the multi-disciplinary team will utilize the local design professional community with timber experience and Portland State University's recently implemented Green Building Scholars program to deliver technical outcomes that directly impact the surrounding environment. Research outcomes will advance knowledge at the system performance level as well as at the critical component level. The investigated building system will incorporate cross laminated timber cores, floors, and glulam structural members. Using mass timber will present challenges in effectively achieving the goal of desirable seismic performance, especially seismic resiliency. These challenges will be addressed at the system level by a unique combination of core rocking combined with beam and floor interaction to achieve non-linear elastic behavior. This system behavior will eliminate the need for post-tensioning to achieve re-centering, but will introduce new parameters that can directly influence the lateral behavior. This research will study the effects of these parameters on the overall building behavior and will develop a methodology in which designers could use these parameters to strategically control the building seismic response. These key parameters will be investigated using parametric numerical analyses as well as large-scale, sub-system experimentation. One of the critical components of the system will be the hold-down, a device that connects the timber core to the foundation and provides hysteretic energy dissipation. Strength requirements and deformation demands in mid- to high-rise buildings, along with integration with mass timber, will necessitate the advancement of knowledge in developing this low-damage component. The investigated hold-down will have large deformation capability with readily replaceable parts. Moreover, the hold-down will have the potential to reduce strength of the component in a controlled and repeatable way at large deformations, while maintaining original strength at low deformations. This component characteristic can reduce the overall system overstrength, which in turn will have beneficial economic implications. Reducing the carbon footprint of new construction, linking rural and urban economies, and increasing the longevity of buildings in seismic zones are all goals that this mass timber research will advance and will be critical to the sustainable development of cities moving forward.
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An Uplift Friction Damper for Seismically Resilient Mass-Timber Buildings

https://research.thinkwood.com/en/permalink/catalogue2799
Topic
Design and Systems
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Hybrid Building Systems
Organization
Michigan Technological University
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Hybrid Building Systems
Topic
Design and Systems
Seismic
Keywords
Seismic Force Resisting System
Uplift Friction Damper
Energy Dissipation
Self-Centering
Numerical Model
Tall Wood Buildings
National Earthquake Hazards Reduction Program
Research Status
In Progress
Notes
Project contact is Daniel Dowden at Michigan Technological University
Summary
This award will investigate a low-damage solution for cross-laminated timber (CLT) seismic force-resisting systems (SFRSs) using a novel uplift friction damper (UFD) device for seismically resilient mass-timber buildings. The UFD device will embrace the natural rocking wall behavior that is expected in tall CLT buildings, provide stable energy dissipation, and exhibit self-centering characteristics. Structural repair of buildings with these devices is expected to be minimal after a design level earthquake. Although CLT has emerged as a construction material that has revitalized the timber industry, there exists a lack of CLT-specific seismic energy dissipation devices that can integrate holistically with the natural kinematics of CLT-based SFRSs. CLT wall panels themselves do not provide any measurable seismic energy dissipation. As a payload to the large-scale, ten-story CLT building specimen to be tested on the Natural Hazards Engineering Research Infrastructure (NHERI) shake table at the University of California, San Diego, as part of NSF award 1636164, “Collaborative Research: A Resilience-based Seismic Design Methodology for Tall Wood Buildings,” this project will conduct a series of tests with the UFD devices installed on the CLT building specimen. These tests will bridge analytical and numerical models with the high fidelity test data collected with realistic boundary and earthquake loading conditions. The calibrated models will be incorporated in a probabilistic numerical framework to establish a design methodology for seismically resilient tall wood buildings, leading to a more diverse and eco-sustainable urban landscape. This project will provide local elementary school outreach activities, integrate participation of undergraduate minorities and underrepresented groups into the research activities, and foster graduate level curriculum innovations. Project data will be archived and made available publicly in the NSF-supported NHERI Data Depot (https://www.DesignSafe-CI.org). This award contributes to NSF's role in the National Earthquake Hazards Reduction Program (NEHRP). The research objectives of this payload project are to: 1) bridge the fundamental mechanistic UFD models linking analytical and numerical models necessary for seismic response prediction of seismically resilient CLT-based SFRSs, 2) characterize the fundamental dynamic UFD behavior with validation and calibration through large-scale tests with realistic boundary conditions and earthquake loadings, and 3) integrate low-damage, friction-based damping system alternatives within a resilience-based seismic design methodology for tall wood buildings. To achieve these objectives, the test data collected will provide a critical pathway to reliably establish numerical and analytical models that extend the shake table test results to a broad range of archetype buildings. The seismic performance of mass-timber archetype building systems will be established through collapse risk assessment using incremental dynamic analyses. This will provide a first step in the longer term goal of establishing code-based seismic performance factors for CLT-based SFRSs.
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Ascent - Challenges and Advances of Tall Mass Timber Construction

https://research.thinkwood.com/en/permalink/catalogue2751
Year of Publication
2020
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Light Frame (Lumber+Panels)
Application
Wood Building Systems
Author
Fernandez, Alejandro
Komp, Jordan
Peronto, John
Publisher
KoreaScience
Year of Publication
2020
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Light Frame (Lumber+Panels)
Application
Wood Building Systems
Topic
Design and Systems
Keywords
Tall Timber
Tall Timber Buildings
United States
Ascent
Challenges
Structural
Research Status
Complete
Series
International Journal of High-Rise Buildings
Summary
Ascent, a 25 story residential tower located in Milwaukee, WI (USA), will become the tallest timber building in the world upon completion. This paper discusses the project's structural system, permit process, groundbreaking project specific testing, and several of the challenges the team overcame, all of which open the door to future Mass Timber projects; particularly in the United States.
Online Access
Free
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Behaviour of Cross-laminated Timber Wall Systems Under Monotonic Lateral Loading

https://research.thinkwood.com/en/permalink/catalogue2404
Year of Publication
2019
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Walls
Author
McPolin, Daniel
Hughes, C.
McGetrick, P.
McCrum, D.
Publisher
Taylor&Francis Online
Year of Publication
2019
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Walls
Topic
Seismic
Keywords
Tall Timber Buildings
Lateral Load
Earthquake
Research Status
Complete
Series
Journal of Structural Integrity and Maintenance
Online Access
Free
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Behaviour of Multi-Storey Cross-Laminated Timber Buildings Under Lateral Loading

https://research.thinkwood.com/en/permalink/catalogue2715
Year of Publication
2020
Topic
Connections
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Walls
Author
Hughes, Claire
Publisher
Queen's University Belfast
Year of Publication
2020
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Walls
Topic
Connections
Design and Systems
Keywords
Lateral Loading
Tall Wood
Tall Timber Buildings
Connections
Monotonic Loading Tests
Constant Vertical Load
Wall Systems
Experimental Tests
Analytical Approach
Multi-Storey
Research Status
Complete
Summary
In response to the global drive towards sustainable construction, CLT has emerged as a competitive alternative to other construction materials. CLT buildings taller than 10-storeys and CLT buildings in regions of moderate to high seismicity would be subject to higher lateral loads due to wind and earthquakes than CLT buildings which have already been completed. The lack of structural design codes and limited literature regarding the performance of CLT buildings under lateral loading are barriers to the adoption of CLT for buildings which could experience high lateral loading. Previous research into the behaviour of CLT buildings under lateral loading has involved testing of building components. These studies have generally been limited to testing wall systems and connections which replicate configurations at ground floor storeys in buildings no taller than three storeys. Consequently, to develop the understanding of the performance of multi-storey CLT buildings under lateral loading, the performance of wall systems and connections which replicate conditions of those in above ground floor storeys in buildings taller than three storeys were experimentally investigated. The testing of typical CLT connections involved testing eighteen configurations under cyclic loading in shear and tension. The results of this experimental investigation highlighted the need for capacity-based design of CLT connections to prevent brittle failure. It was found that both hold down and angle bracket connections have strength and stiffness in shear and tension and by considering the strength of the connections in both directions, more economical design of CLT buildings could be achieved. The testing of CLT wall systems involved testing three CLT wall systems with identical configurations under monotonic lateral load and constant vertical load, with vertical loads replicating gravity loads at storeys within a 10-storey CLT building. The results show that vertical load has a significant influence on wall system behaviour; varying the vertical load was found to vary the contribution of deformation mechanisms to global behaviour within the elastic region, reinforcing the need to consider connection design at each individual storey. As there are still no structural design codes for CLT buildings, the accuracy of analytical methods presented within the literature for predicting the behaviour of CLT connections and wall systems under lateral loading was assessed. It was found that the analytical methods for both connections and wall systems are highly inaccurate and do not reflect experimentally observed behaviour.
Online Access
Free
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Carbon Impact and Cost of Mass Timber Beam–Column Gravity Systems

https://research.thinkwood.com/en/permalink/catalogue2883
Year of Publication
2021
Topic
Environmental Impact
Application
Frames
Author
Chaggaris, Rachel
Pei, Shiling
Kingsley, Greg
Feitel, Alexis
Organization
Colorado School of Mines
Editor
Ganguly, Indroneil
Publisher
MDPI
Year of Publication
2021
Format
Journal Article
Application
Frames
Topic
Environmental Impact
Keywords
IBC
Tall Wood Buildings
Gravity Framing System
Embodied Carbon
Mass Timber
Biogenic Carbon
Research Status
Complete
Series
Sustainability
Summary
The need to lower the embodied carbon impact of the built environment and sequester carbon over the life of buildings has spurred the growth of mass timber building construction, leading to the introduction of new building types (Types IV-A, B, and C) in the 2021 International Building Code (IBC). The achievement of sustainability goals has been hindered by the perceived first cost assessment of mass timber systems. Optimizing cost is an urgent prerequisite to embodied carbon reduction. Due to a high level of prefabrication and reduction in field labor, the mass timber material volume constitutes a larger portion of total project cost when compared to buildings with traditional materials. In this study, the dollar cost, carbon emitted, and carbon sequestered of mass timber beam–column gravity system solutions with different design configurations was studied. Design parameters studied in this sensitivity analysis included viable building types, column grid dimension, and building height. A scenario study was conducted to estimate the economic viability of tall wood buildings with respect to land costs. It is concluded that, while Type III building designations are the most economical for lower building heights, the newly introduced Type IV subcategories remain competitive for taller structures while providing a potentially significant embodied carbon benefit.
Online Access
Free
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Design and Performance of High-Rise Structure using Ultra-Lightweight Cross Laminated Timber Floor System

https://research.thinkwood.com/en/permalink/catalogue2698
Year of Publication
2020
Topic
Mechanical Properties
Serviceability
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Ahmed, Danish
Ayadat, Tahar
Asiz, Andi
Publisher
ISEC Press
Year of Publication
2020
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Mechanical Properties
Serviceability
Keywords
Tall Timber Buildings
Lateral Load
Lateral Deflections
Floor Diaphragm
Conference
International Structural Engineering and Construction Conference
Research Status
Complete
Series
Proceedings of International Structural Engineering and Construction
Summary
The main objective of this paper is to study the structural performance of a high-rise structure when alternative lightweight material known as cross-laminated timber was used as a slab in floor system in lieu of conventional reinforced concrete slab. A numerical case study was conducted using a highly irregular RC frame building with its two 60-story towers joined at the top. Three major analyses were considered. First, modeling and analyzing the building with an RC slab was conducted to determine the design reference. Second, substituting the RC slab with the CLT slab was performed using the same building skeleton. Third, redesigning and optimizing the building skeleton with that CLT to observe skeleton material saving obtained using the same structural performance criteria. Major lateral loads applicable in the Eastern Province of Saudi Arabia were inputted. Strengths and serviceability requirements for floor diaphragm and lateral load resisting system were checked first before performing a comparative analysis between traditional RC and CLT slabs as floor diaphragm. The structural performance criteria to be used for comparative study between RC and CLT slabs included total drift, inter-story drift due to lateral loads, and base reactions. Structural periods and acceleration responses for each floor were investigated and contrasted with the existing building code. The foundation demand was also investigated based on the structural weight and reactions generated from the RC and CLT floor systems.
Online Access
Free
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Developing a Large Span Timber-based Composite Floor System for Highrise Office Buildings

https://research.thinkwood.com/en/permalink/catalogue2549
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Floors
Hybrid Building Systems
Material
CLT (Cross-Laminated Timber)
Application
Floors
Hybrid Building Systems
Topic
Design and Systems
Keywords
Large Span
Prefabrication
High-Rise
Office Buildings
Tall Timber Buildings
Research Status
In Progress
Notes
Project contact is Frank Lam at the University of British Columbia
Summary
The objective of this project is to develop a large span timber-based composite floor system for the construction of highrise office buildings. This prefabricated floor system could span over 10 m under regular office occupation load, and its use will expedite the construction significantly, converting to multi-million financial savings in a typical 40+ story project, besides the impact on reducing carbon footprint and enhancing living experience.
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Developing a Large Span Timber-based Composite Floor System for Highrise Office Buildings Phase I

https://research.thinkwood.com/en/permalink/catalogue2803
Year of Publication
2021
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
LVL (Laminated Veneer Lumber)
LSL (Laminated Strand Lumber)
Glulam (Glue-Laminated Timber)
Application
Floors
Author
Zhang, Chao
Lee, George
Lam, Frank
Organization
University of British Columbia
Year of Publication
2021
Format
Report
Material
CLT (Cross-Laminated Timber)
LVL (Laminated Veneer Lumber)
LSL (Laminated Strand Lumber)
Glulam (Glue-Laminated Timber)
Application
Floors
Topic
Design and Systems
Keywords
Box Girder
Timber Composite Floor
Span
High-Rise
Tall Wood Buildings
Stiffness
Composite Action
Research Status
Complete
Summary
This project proposes a timber-based composite floor that can span 12 m and be used in the construction of 40+ story office buildings. This floor system integrates timber panels and timber beams to form a continuous box girder structure. The timber panels function as the flanges and the timber beams as the web. The beams are spaced and connected to the flange panels so that sufficient bending stiffness of a 12 m span can be achieved via the development of composite action. The current phase of this project studied the performance of the connections between timber elements in the proposed composite member. Six types of connections using different flange material and connection techniques were tested: Cross Laminated Timber (CLT), Laminated Strand Lumber (LSL), Laminated Veneer Lumber (LVL), and Post Laminated Veneer Lumber (PLVL). Glulam was used as the web. The majority of the connections used self-tapping wood screws except one had notches. The load-carrying capacity, stiffness, and ductility of the connections were measured. The stiffness of CLT, LSL, and PLVL connections was in the same range, 19-20 kN/mm per screw. Amongst the three, LSL had the highest peak load and PLVL had the highest proportional limit. The stiffness of the two LVL screw connections was around 13 kN/mm. The notched LVL connection had significantly higher stiffness than the rest, and its peak load was in the same range as LSL, but the failure was brittle. LVL was used to manufacture the full scale timber composite floor element. With a spacing of 400 mm, the overall stiffness reached 33689 N
mm2×109, which was 2.5 times the combined stiffness of two Glulam beams. The predicted overall stiffness based on Gamma method was within 5% of the tested value, and the estimated degree of composite action was 68%. From both the test results and analytical modeling, the number of screws may be further reduced to 50% or less of the current amount, while maintaining a high level of stiffness. Future work includes testing the composite floor under different screw spacings, investigating the effect of concrete topping, and the connections between floor members and other structural elements.
Online Access
Free
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Developments in Tall Wood and Hybrid Buildings and Environmental Impacts

https://research.thinkwood.com/en/permalink/catalogue3005
Year of Publication
2021
Topic
Environmental Impact
Application
Wood Building Systems
Hybrid Building Systems
Author
Iqbal, Asif
Organization
University of Northern British Columbia
Editor
Gupta, Rishi
Publisher
MDPI
Year of Publication
2021
Format
Journal Article
Application
Wood Building Systems
Hybrid Building Systems
Topic
Environmental Impact
Keywords
Tall Wood Buildings
Hybrid Structures
Sustainable Construction
Research Status
Complete
Series
Sustainability
Summary
Wood has been gaining popularity as a building material over the last few decades. There has been significant progress in technology during this period to push the limits of wood construction. At the same time, it has become more economically competitive to build with wood beyond low-rises. As a result, there has been a noteworthy shift in public perception in terms of acceptance of wood as a material for high-rise buildings. There is a growing list of tall wood buildings that have been constructed in different continents over the last decade. With worldwide population growth and increased urbanization, the trend is expected to continue. Considerable urgency for using sustainable resources to tackle the threat of climate change has resulted in a surge in demand as well as applications in recent decades. This paper reviews the significant technical advances that have contributed to those achievements and are expected to facilitate further developments.
Online Access
Free
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28 records – page 1 of 3.