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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
Country of Publication
United States
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.
Resource Link
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Structural Testing for Framework Office Building in Portland, OR

https://research.thinkwood.com/en/permalink/catalogue1829
Year of Publication
2017
Topic
Design and Systems
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Walls
Wood Building Systems
Organization
Oregon State University
Portland State University
Year of Publication
2017
Country of Publication
United States
Format
Report
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Walls
Wood Building Systems
Topic
Design and Systems
Mechanical Properties
Keywords
Crushing Test
In-Plane Shear Test
Beam-Column Connection
Panels
Earthquake
Language
English
Research Status
Complete
Series
Framework: An Urban + Rural Design
Summary
A. Structural Test Results Summary B. Test 1, 2, 3: 1. CLT Crushing Test Report 2. Bare CLT Wall Panel Test Report 3. CLT In-Plane Shear Wall Test Report C. Glulam Beam-Column Connection Test Report
Online Access
Free
Resource Link
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Towards Resilient Mass Timber Systems: Understanding Durability of Cross-Laminated Timber Connections

https://research.thinkwood.com/en/permalink/catalogue2293
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Organization
Oregon State University
Portland State University
Country of Publication
United States
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Keywords
Durability
Mass Timber
Moisture
Ultrasonic
Cyclic Loading Tests
Research Status
In Progress
Notes
Project contact is Arijit Sinha.
Summary
Cross Laminated Timber (CLT) is gaining acceptance in tall building applications in the US. However, there are knowledge gaps concerning long-term performance, particularly effects due to moisture intrusion and biological decay in relation to connection systems. In a risk-averse industry, this knowledge gap impedes acceptance of CLT. The overall goal of the project is to characterize the effects of moisture accumulation in mass timber buildings on properties of building components and connections. The project will assess CLT connectors using small-scale assemblies, then use these data to develop predictive models that will be compared with full-scale tests. Connection assemblies will be constructed with two wood species and exposed to five moisture/biological regimes. Moisture behavior in the assemblies will be characterized using a combination of non-destructive tools, such as ultrasonic, wave propagation, CAT-Scan, and infrared imaging. The data generated from cyclic loading tests will be used to calibrate the SAWS connection model. This will provide a novel way to estimate the effects of moisture and biological degradation on connections. A deliverable for this project is a design guideline for engineers to account for the effects of moisture intrusion and subsequent fungal decay on panel and connection properties.
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