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27 records – page 1 of 3.

Ability of Finger-Jointed Lumber to Maintain Load at Elevated Temperatures

https://research.thinkwood.com/en/permalink/catalogue1832
Year of Publication
2018
Topic
Fire
Material
Other Materials
Author
Rammer, Douglas
Zelinka, Samuel
Hasburgh, Laura
Craft, Steven
Publisher
Forest Products Laboratory
Year of Publication
2018
Format
Journal Article
Material
Other Materials
Topic
Fire
Keywords
Small Scale
Full Scale
Bending Test
Melamine Formaldehyde
Phenol-Resorcinol Formaldehyde
Creep
Polyurethane
Polyvinyl Acetate
Temperature
Durability
Research Status
Complete
Series
Wood and Fiber Science. 50(1): 44-54.
Summary
This article presents a test method that was developed to screen adhesive formulations for finger-jointed lumber. The goal was to develop a small-scale test that could be used to predict whether an adhesive would pass a full-scale ASTM E119 wall assembly test. The method involved loading a 38-mm square finger-jointed sample in a four-point bending test inside of an oven with a target sample temperature of 204°C. The deformation (creep) was examined as a function of time. It was found that samples fingerjointed with melamine formaldehyde and phenol resorcinol formaldehyde adhesives had the same creep behavior as solid wood. One-component polyurethane and polyvinyl acetate adhesives could not maintain the load at the target temperature measured middepth of the sample, and several different types of creep behavior were observed before failure. This method showed that the creep performance of the onecomponent adhesives may be quite different than the performance from short-term load deformation curves collected at high temperatures. The importance of creep performance of adhesives in the fire resistance of engineered wood is discussed.
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An Enhanced Beam Model for Glued Laminated Structures that takes Moisture, Mechano-sorption and Time Effects into Account

https://research.thinkwood.com/en/permalink/catalogue44
Year of Publication
2014
Topic
Moisture
Serviceability
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Ormarsson, Sigurdur
Steinnes, Jan
Year of Publication
2014
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Moisture
Serviceability
Keywords
Climate
Creep
Finite Element Model
Hygro-Mechanical
Long-term
Visco-Elastic
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
There is a need of more advanced analysis for studying how the long-term behaviour of glued laminated timber structures is affected by creep and by cyclic variations in climate. A beam theory is presented able to simulate the overall hygro-mechanical and visco-elastic behaviour of (inhomogeneous) glulam structures. Two frame structures subjected to both mechanical and cyclic environmental loading are analysed to illustrate the advantages the model involved can provide. The results indicate clearly both the (discontinuous) inhomogeneity of the glulam products and the variable moisture-load action that occurs to have a significant effect on deformations, section forces and stress distributions within the frame structures that were studied
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Creep and Duration Of Load Characteristics of Cross Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue692
Year of Publication
2014
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Nakajima, Shiro
Miyatake, Atsushi
Shibuwasa, Tatsuya
Araki, Yasuhiro
Yamaguchi, Nobuyoshi
Haramiishi, Takeshi
Ando, Naoto
Yasumura, Motoi
Year of Publication
2014
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Cedar
Creep
Duration of Load
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
Creep and duration of load characteristics of cross laminated timber (CLT) were evaluated from the test results of creep and duration of tests. Japanese Ceder (Cryptomeria japonica) was chosen for the specie for the laminations of the test specimens and API was chosen for the adhesive. The results are summarized as follows: (1) The creep factor [i.e. (Initial deflection + Creep deflection) / Initial deflection] for CLT was evaluated to be 2.0 and was almost equivalent to the creep factor commonly known for solid lumber. (2) The duration of load factor [i.e. Strength for 50 years duration of load / Strength for 10 minutes duration of load] of CLT was evaluated to be 0.66 and was almost equivalent to the duration of load factor measured for solid lumbers.
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Creep Behavior of Laminated Veneer Lumber from Poplar Under Cyclic Humidity Changes

https://research.thinkwood.com/en/permalink/catalogue2480
Year of Publication
2019
Topic
Mechanical Properties
Moisture
Material
LVL (Laminated Veneer Lumber)

Differential Material Movement in Tall Mass Timber Structures

https://research.thinkwood.com/en/permalink/catalogue2982
Year of Publication
2022
Topic
Moisture
Application
Wood Building Systems
Author
Racine, Josephine
Lumpkin, Bryce
McLain, Richard
Organization
Fast + Epp
WoodWorks
Year of Publication
2022
Format
Report
Application
Wood Building Systems
Topic
Moisture
Keywords
Column Movement
Vertical Movement
Creep
Settlement
Shrinkage
Crushing Perpendicular to Grain
Research Status
Complete
Summary
As the height of mass timber buildings continues to grow, a new set of design and detailing challenges arises, creating the need for new engineering solutions to achieve optimal building construction and performance. One necessary detailing consideration is vertical movement, which includes column shrinkage, joint settlement, and creep. The main concerns are the impact of deformations on vertical mechanical systems, exterior enclosures, and interior partitions, as well as differential vertical movement of timber framing systems relative to other building features such as concrete core walls and exterior façades.
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Evaluation and Optimization of the Vibration Behavior of CLT-Concrete Floors

https://research.thinkwood.com/en/permalink/catalogue2673
Topic
Acoustics and Vibration
Material
Timber-Concrete Composite
CLT (Cross-Laminated Timber)
Application
Floors
Organization
Université Laval
Material
Timber-Concrete Composite
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Finite Element Method (FEM)
Vibration Performance
Creep
Displacement
Natural Frequency
Research Status
In Progress
Notes
Project contact is Sylvain Ménard at Université Laval
Summary
Designers of large buildings generally want floor systems with large spans (9 m). These floors are often sized by the requirement of vibratory performance and, correlatively, deflection. The composite wood-concrete floors allow large spans with reduced static height. They are a promising alternative to simple concrete slabs. Objective 1 - Determine the evolution of the natural frequency of the CLT-concrete composite floor as a function of the stiffness of the connector, and correlate the experimental results with the model by the finite element method. Objective 2 - Parametric study of the vibration performance of the CLT-concrete composite floor. The impact of several parameters on the dynamic performance of the floor will be determined, especially the characteristics of the constituent materials, connector and the creep of the floor. Objective 3 - Build the metamodels for the study of multi-objective optimization optimization of a wood-concrete composite floor solution in relation to a regional problem in Aquitaine.
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Experimental Investigation on Long-term Axial Creep Performance of Pine, Spotted Gum and Laminated Veneer Lumber

https://research.thinkwood.com/en/permalink/catalogue2485
Year of Publication
2019
Topic
Design and Systems
Material
LVL (Laminated Veneer Lumber)
Application
Wood Building Systems

Experimental Study on Flexural Performance of the Prestressed Glulam Continuous Beam after Long-Term Loading

https://research.thinkwood.com/en/permalink/catalogue3118
Year of Publication
2022
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Guo, Nan
Zhang, Yunan
Mei, Lidan
Zhao, Yan
Organization
Northeast Forestry University
Wuyi University
Editor
Chang, Wen-Shao
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Creep
Bending Performance
Experimental Study
Continuous Beam
Research Status
Complete
Series
Buildings
Summary
The study of the long-term behavior of the prestressed continuous beam is vital for the design and the appliance of wood structures in engineering. In this study, long-term experiments were first conducted to determine the long-term creep behavior. Afterward, the prestress of the long-term beam was regulated to the initial state, and we carried out short-term flexural experiments to explore the effect of prestressing regulation. The influences of prestressed value and the number of prestressed steel wires on the mechanical properties of the continuous beam were investigated and discussed. The experimental results demonstrate that the creep reduced the stress in the steel wires, weakened the effect of prestressing, and increased the tensile stress at the bottom of the beam, which led to a reduction in the bearing capacity of the beam. The prestressing regulation could increase the moment arm, so the bearing capacity of the beam was improved.
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Fire and Structural Performance of Non-Metallic Timber Connections

https://research.thinkwood.com/en/permalink/catalogue152
Year of Publication
2015
Topic
Connections
Fire
Material
LVL (Laminated Veneer Lumber)
Author
Brandon, Daniel
Organization
University of Bath
Year of Publication
2015
Format
Thesis
Material
LVL (Laminated Veneer Lumber)
Topic
Connections
Fire
Keywords
Creep
Deflection
Dowels
Fiber Reinforced Polymer
Glass Fiber Reinforced Polymer
Model
Densified Veneer Wood
Research Status
Complete
Summary
Recent studies showed the need for timber connections with high fire performance. Connections of members in timber structures commonly comprise steel connectors, such as dowels, screws, nails and toothed plates. However, multiple studies have shown that the presence of exposed metal in timber connections leads to a poor performance under fire conditions. Replacing metallic fasteners with non-metallic fasteners potentially enhances the fire performance of timber connections. Previous studies showed that Glass Fibre Reinforced Polymer (GFRP) dowels can be a viable replacement for steel dowels and that Densified Veneer Wood functions well as a flitch plate material. However, as the resin matrix of GFRP dowels is viscoelastic, connection creep, which is not studied before, can be of concern. Also no research has been carried out on the fire performance of these connections. Therefore, a study of the creep behaviour and the fire performance of non-metallic timber connections comprising GFRP dowels and a Densified Veneer Wood flitch plate was performed, as is discussed in this thesis. Predictive models were proposed to determine the connection slip and load bearing capacity at ambient and elevated temperatures and in a fire. The material properties and heat transfer properties required for these models were determined experimentally and predictions of these models were experimentally validated. Furthermore, an adjustment of the predictive model of connection slip at ambient temperature allowed approximating the creep of the connection. The material properties, required for the creep model, were determined experimentally and predictions of the model were compared to results of longterm connection tests. The study confirmed that timber members jointed with non-metallic connectors have a significantly improved fire performance to timber joints using metallic connections. Models developed and proposed to predict fire performance gave accurate predictions of time to failure. It was concluded that non-metallic connections showed more creep per load per connector, than metallic connections. However, the ratio between initial deflection and creep (relative creep) and the ratio between load level and creep were shown to be similar for metallic and non-metallic connections.
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Long-Term Behavior of Steel-CLT Connections

https://research.thinkwood.com/en/permalink/catalogue2080
Year of Publication
2018
Topic
Connections
Serviceability
Mechanical Properties
Material
Steel-Timber Composite
CLT (Cross-Laminated Timber)
Application
Floors
Author
Chiniforush, Alireza
Akbarnezhad, Ali
Valipour, Hamid
Bradford, Mark
Organization
University of New South Wales
Year of Publication
2018
Format
Conference Paper
Material
Steel-Timber Composite
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Connections
Serviceability
Mechanical Properties
Keywords
Long-term
Load-Slip
Pre-Tension
Bolts
Screws
Creep
Conference
World Conference on Timber Engineering
Research Status
Complete
Summary
Innovative steel - Cross Laminated Timber (CLT) connections are key elements in developing hybrid steel-timber composite floors with desirable strength and serviceability performance. The performance of floors mainly relies on the load-slip behavior of connections for composite action. The long-term behavior of timber is mainly affected by elastic and mechano-sorptive creep, resulting in a different total slip than the initially observed one. In this study, the long-term load-slip behavior of two different types of connections with pre-tensioned high-strength bolts and dog screws are experimentally assessed at two different stress levels. Furthermore, the effect of grain orientation on the results is studied by considering specimens with parallel and perpendicular grain orientations under sustained loads. Load-slip curves show a stable performance of a composite action over time. Furthermore, an analytical model is fitted to the load-slip vs time data which can be used to predict long-term behavior of floors in future.
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27 records – page 1 of 3.