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Cyclic Performance of Connections used in Hybrid Cross-Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue1367
Year of Publication
2017
Topic
Connections
Design and Systems
Material
CLT (Cross-Laminated Timber)
Author
Mahdavifar, Vahid
Organization
Oregon State University
Year of Publication
2017
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Design and Systems
Keywords
North American Market
Density
Low-Grade
High-Grade
Fasteners
Economical
Research Status
Complete
Summary
One of the recent additions to the panoply of engineered wood products is cross-laminated timber (CLT). CLT is a prefabricated, large-scale, solid wood panel that consists of multiple layers of lumbers stacked together, with each layer arranged perpendicular to the next layer, glued with structural grade adhesives, and pressed. The use of massive CLT panels in wood construction provides several advantages over the traditional wood frame systems, making it particularly attractive for tall wood building construction. These main advantages are satisfactory distribution of defects, adequate seismic performance, ability to carry large loads, improved strength and stiffness, adequate acceptable fire performance, acceptable acoustic performance, and improved pre-fabrication.It is expected that as the CLT market will continue to mature, more diversified grades and special CLT products will be introduced into the markets. One special CLT product developed in at Oregon State University has been designated as hybrid CLT. Hybrid CLT refers to CLT panels manufactured with layers of high- and low-grade and low-density species, which aims at improving the economic efficiency and sustainability of the CLT industry with focus on the North America market.One of the potential issues with hybrid CLT panel application is related to the unknown performance of the connection systems which are highly dependent on the density of the wood in which the fasteners embed. Most of the existing models that have been developed for estimation of the fasteners capacities in withdrawal and lateral loading scenarios are developed based on the assumption of uniform density profile across the layers to which fasteners penetrate. In a hybrid CLT panel, there is a possibility of a variation in density profile along the panel thickness so that the fasteners can be driven into wood of different densities and driven in directions parallel and perpendicular to grain. Because of the potential variation in density profile in the hybrid CLT, the connection system performance cannot be predicted using design models used for uniform density profile applications similar to the models in National Design Specification (NDS) [1]. Therefore, there is a need for evaluation of connections performance in hybrid layup.The main objective of this work is to characterize the performance of connection systems for hybrid CLT. This is achieved through testing and modeling of single fastener connections and then testing and modeling of the typical connection systems. So, the specific objectives are: (1) evaluate the single fasteners performance to account for density variation and compare the results to a proposed modified model, (2) perform an experimental program to test different connection systems with different hybrid CLT panel layups, (3) develop a numerical algorithm based on the use of meta-heuristics tools to fit the optimal parameters for constitutive models to match the experimental data for the connection systems, (4) obtain the optimal parameters for constitutive models of the connection systems tested.
Online Access
Free
Resource Link
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Post-Tensioned Timber Frame Structures

https://research.thinkwood.com/en/permalink/catalogue63
Year of Publication
2015
Topic
Connections
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Columns
Author
Wanninger, Flavio
Organization
ETH Zurich
Year of Publication
2015
Format
Thesis
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Columns
Topic
Connections
Keywords
Moment Resistance
Economical
Timber Joints
Moment-Rotation
Bending Test
Pushover Test
Numerical Modeling
Research Status
Complete
Summary
The present research report was written as a PhD thesis (ETH Dissertation Nr. 22815) by Flavio Wanninger and shows the results of a comprehensive experimental and numerical analysis on the structural behaviour of post-tensioned timber frame, in particular with focus on the momentrotation-behaviour of the developed post-tensioned beam-column timber joint using hardwood and the long-term behaviour of the system. The results of the experimental and numerical investigations provide reliable data for the development and validation of calculation models for the design of post-tensioned timber frames with hardwood for vertical and horizontal loads and taking into account the long-term behaviour. The objective of the research project is the development and implementation of post-tensioned timber frame structures into the practice and fits well into the overall research strategy of the institute on the development of innovative solutions for timber structures.
Online Access
Free
Resource Link
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Progress on the Development of Seismic Resilient Tall CLT Buildings in the Pacific Northwest

https://research.thinkwood.com/en/permalink/catalogue178
Year of Publication
2014
Topic
Seismic
Market and Adoption
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
Market and Adoption
Keywords
Commercial
High-Rise
Residential
US Market
Economical
Sustainable
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
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
Online Access
Free
Resource Link
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