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Analytical and experimental evaluation of the effect of knots on rolling shear properties of cross-laminated timber (CLT)

https://research.thinkwood.com/en/permalink/catalogue1942
Year of Publication
2019
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Cao, Yawei
Organization
Mississippi State University
Year of Publication
2019
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Rolling Shear
Southern Pine
Center Point Bending Test
Two-Plate Shear Test
Knots
Strength
Failure Mechanism
Research Status
Complete
Summary
Knots are usually regarded as defects when grading lumber. In order to evaluate a member under out-of-plane loading, shear strength is one of the major mechanical properties, specifically, rolling shear (RS) strength is one of the critical mechanical properties of Cross-Laminated Timber (CLT), which determines the flexural strength of CLT under short-span bending loads. Lower grade lumber with a higher percentage of knots is recommended to be utilized for the cross-layer laminations which are mainly responsible for resisting shear stresses. Firstly, shear tests were performed in order to evaluate the effect of knots on longitudinal shear strength using shear blocks. After that, the effect of knots on the RS strength of 3-ply southern yellow pine CLT were investigated by experimental tests and an analytical model. Center-point bending tests with a span-to-depth ratio of 6 and two-plate shear tests with a loading angle of 14° were conducted on six CLT configurations composed of different types of cross layer laminations: clear flatsawn lumber with/without pith, lumber with sound knots with/without pith, and lumber with decayed knots with/without pith. The shear analogy method was implemented to evaluate the RS strength values from the bending test results, which were also compared against the results from the two-plate shear tests. It was found that: (1) The shear blocks containing sound knots had higher shear strength than matched clear shear blocks, the shear blocks containing unsound knots had lower shear strength than the matched clear shear blocks. (2) CLT specimens with cross-layer laminations with either sound knots or decayed knots had higher RS strength. (3) In general, the shear analogy method underestimated the RS strength of CLT specimens containing knots and pith.
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Bending and Rolling Shear Capacities of Southern Pine Cross Laminated Timber (CLT)

https://research.thinkwood.com/en/permalink/catalogue1596
Year of Publication
2016
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Gu, Mengzhe
Pang, Weichiang
Stoner, Michael
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Southern Pine
US
Manufacturing
Rolling Shear
Bending
Three Point Bending Test
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 1899-1906
Summary
Southern Pine (SP) is one of the fastest growing softwood species in the Southern Forest of United States. With its high strength to weight ratio, SP becomes an ideal candidate for manufacturing engineered wood products such as cross laminated timber (CLT). Two batches of CLT panels were manufactured using visually graded SP lumbers in this study: pilot-scale panels in a laboratory setting and full-size panels in a manufacturing plant environment. The first batch of pilot-scale CLT panels was manufactured at Clemson University. The second batch of full-scale CLT panels (3m x 12.2m) was produced and CNC-sized by Structurlam in Penticton, Canada and shipped to Clemson University for testing. Four types of structural wood adhesives were selected in the panel production, namely Melamine Formaldehyde (MF), Phenol Resorcinol Formaldehyde (PRF), Polyurethane (PUR) and Emulsion Polymer Isocyanate (EPI). This paper presents the manufacturing process of SP CLT in a laboratory setting as well as structural performance verification of 3- ply SP CLT in terms of rolling shear and bending properties. The obtained performance data of 3-ply CLT in both major and minor strength directions is verified against PRG-320 Standard for Performance Rated Cross Laminated Timber. Tested results are presented and discussed.
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Bending Properties of Cross Laminated Timber with Layer Arrangement Using Different Species

https://research.thinkwood.com/en/permalink/catalogue1599
Year of Publication
2016
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Park, Sun-Hyang
Kim, Keon-Ho
Lee, Sang-Joon
Pang, Sung-Jun
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Delamination Test
Bending Test
Japanese Larch
Korean Red Pine
Shear Strength
MOE
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 1931-1938
Summary
To evaluate the mechanical performance of the cross laminated timber (CLT) as the structural board materials using domestic species, the delamination test and the transverse bending test were conducted. The CLT used in the tests consisted of 3 layers of laminated timber made of Japanese larch and Korean red pine. The combinations for lamination were then divided on species of layer and grades of laminae. In the bending test, the loading directions were shown to be parallel and perpendicular to width direction of specimens, which is considered as the applicable direction in wooden building. The result of test showed that the bending strength of larix CLT was higher than that of pine CLT in combination of single species. In case of combination of mixed species, the bending properties CLT using larix major layer was higher than those of pine surface layer. It means that the surface layer has a more influence on bending properties of CLT, than the core layer does.
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Comparison of Bonding Performance Between Plywood and Laminated Veneer Lumber Induced by High Voltage Electrostatic Field

https://research.thinkwood.com/en/permalink/catalogue2487
Year of Publication
2019
Topic
Mechanical Properties
Design and Systems
Material
LVL (Laminated Veneer Lumber)
Other Materials
Application
Wood Building Systems

Comparison of Bonding Performance Between Plywood and Laminated Veneer Lumber Induced by High Voltage Electrostatic Field

https://research.thinkwood.com/en/permalink/catalogue2501
Year of Publication
2019
Topic
Mechanical Properties
Design and Systems
Material
LVL (Laminated Veneer Lumber)
Application
Wood Building Systems

Comparison of Various Glulam in Physical Properties and Flexural Behaviors

https://research.thinkwood.com/en/permalink/catalogue642
Year of Publication
2013
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Qiu, Jing
Tong, Jianhong
Hui Chen, Li
Publisher
Scientific.net
Year of Publication
2013
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Mechanical Properties
Keywords
Douglas-Fir
Flexural Behavior
Physical Properties
Larch
Modulus of Rupture
Pine
Poplar
Research Status
Complete
Series
Applied Mechanics and Materials
Summary
The glulam is determined by, and therefore a representation of, a new kind of ecological structural materials. The aim of this study was to summarize the mechanical performance especially the flexural behavior of various kinds of glulam and the physical properties of their relevant original timbers including pseudotsuga menziesii, larch, Yi poplar, poplar, China fir, mongolian scotch pine and camphor. And then it established and analyzed the relationship between the two to contrast those timber species so as to provide engineers with some reference in selecting timber glulam.
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Cyclic Testing and Simulation of Hold Down Connections in Radiata Pine CLT Shear Walls

https://research.thinkwood.com/en/permalink/catalogue1605
Year of Publication
2016
Topic
Connections
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Benedetti, Franco
Rosales, Víctor
Opazo, Alexander
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Connections
Mechanical Properties
Keywords
Pine
Hold-Down
Hysteretic Model
Cyclic Loading
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 2041-2050
Summary
Structures built with cross laminated timber (CLT) are an attractive alternative to traditional construction materials in terms of environmental performance and habitability, but its structural behavior is not well understood for each timber specie. This work provides a comprehensive study of the structural behavior of radiata pine CLT shear walls, by means of laboratory testing and numerical analysis of hold down connections. The observed test response of connections is replicated by calibrating two hysteretic models on OpenSees, and its fidelity is revised through the analysis of a full scale wall test and simulation. Main outcomes suggest that advanced modelling tools can accurately reproduce the hysteretic behaviour of the connections of timber panels. In terms of connections behaviour, it is observed that hold downs on radiata pine CLT elements reach less load capacity than hold downs on other wood specie, and no significant difference with the parallel to grain capacity of angle brackets connections is noticed. Besides, it is found that radiata pine CLT walls can achieve suitable cyclic loading performance and reach high levels of displacement ductility. Furthermore, the importance of friction on the load capacity of the wall is showed.
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Design Methods for Load-Bearing Elements from Cross Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue1116
Year of Publication
2015
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Author
Vilguts, Aivars
Serdjuks, Dmitrijs
Goremikins, Vadims
Publisher
IOP Publishing Ltd
Year of Publication
2015
Format
Report
Material
CLT (Cross-Laminated Timber)
Topic
Design and Systems
Keywords
FEM
Bending
Compression
Static Load
Pine
Uniformly Distributed Load
Strength
Stiffness
Conference
International Conference on Innovative Materials, Structures and Technologies
Research Status
Complete
Notes
September 30-October 2 2015, Riga, Latvia
Summary
Cross-laminated timber is an environmentally friendly material, which possesses a decreased level of anisotropy in comparison with the solid and glued timber. Cross-laminated timber could be used for load-bearing walls and slabs of multi-storey timber buildings as well as decking structures of pedestrian and road bridges. Design methods of cross-laminated timber elements subjected to bending and compression with bending were considered. The presented methods were experimentally validated and verified by FEM. Two cross-laminated timber slabs were tested at the action of static load. Pine wood was chosen as a board's material. Freely supported beam with the span equal to 1.9 m, which was loaded by the uniformly distributed load, was a design scheme of the considered plates. The width of the plates was equal to 1 m. The considered cross-laminated timber plates were analysed by FEM method. The comparison of stresses acting in the edge fibres of the plate and the maximum vertical displacements shows that both considered methods can be used for engineering calculations. The difference between the results obtained experimentally and analytically is within the limits from 2 to 31%. The difference in results obtained by effective strength and stiffness and transformed sections methods was not significant.
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Development of Modular System in Midrise to Tall Wood Buildings Phase II

https://research.thinkwood.com/en/permalink/catalogue2530
Year of Publication
2020
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Author
Zhang, Chao
Organization
Timber Engineering and Applied Mechanics (TEAM) Laboratory
Year of Publication
2020
Format
Report
Material
CLT (Cross-Laminated Timber)
Topic
Design and Systems
Keywords
Openings
Lateral Performance
Shear Walls
SPF
Spruce-Pine-Fir
Loading Tests
Research Status
Complete
Summary
This project studied the effect of openings on the lateral performance of CLT shear walls and the system behavior of the walls in a module. Three-layer Cross Laminated Timber (CLT) was used for manufacturing the wall and module specimens. The laminar was Spruce-Pine-Fir (SPF) #2&Better for both the major and minor layers. Each layer was 35 mm thick. The panel size was 2.44 m × 2.44 m. Four configurations of walls were investigated: no opening, 25% opening, 37.5% opening, and 50% opening. The opening was at the center of the wall and in the shape of a square. A CLT module was made from two walls with 50% openings, with an overall thickness of 660 mm. The specimens were tested under monotonic loading and reverse-cyclic loading, in accordance with ASTM E564-06 (2018) and ASTM E2126-19. The wall without opening had an average peak load of 111.8 kN. It had little internal deformation and the failure occurred at the connections. With a 25% opening, deformation within the wall was observed but the failure remained at the connections. It had the same peak load as the full wall. When the opening was increased to 37.5%, the peak load decreased by 6% to 104.9 kN and the specimens failed in wood at the corners of the opening. Further increasing the opening to 50%, the peak load dropped drastically to 63.4 kN, only 57% of the full wall. The load-displacement relationship was approximately linear until the load reached 60% of the peak or more. Compared to the full wall, the wall with 25% opening had 65% of the stiffness. When the opening increased to 37.5% and 50%, the stiffness reduced to 50% and 24% of the full wall, respectively. The relationship between stiffness and opening ratio was approximately linear. The loading protocol had effect on the peak load but not on the stiffness. There was more degradation for larger openings under reverse-cyclic loading. The performance of the module indicated the presence of system effect that improves the ductility of the wall, which is important for the seismic performance of the proposed midrise to tall wood buildings. The test data was compared to previous models found in literature. Simplified analytical models were also developed to estimate the lateral stiffness and strength of CLT wall with openings.
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Development of Southern Pine Cross-Laminated Timber for Building Code Acceptance

https://research.thinkwood.com/en/permalink/catalogue474
Year of Publication
2014
Topic
Acoustics and Vibration
Fire
Mechanical Properties
Market and Adoption
Material
CLT (Cross-Laminated Timber)
Author
Hindman, Daniel
Bouldin, John
Year of Publication
2014
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Acoustics and Vibration
Fire
Mechanical Properties
Market and Adoption
Keywords
Southern Pine
Fire Performance
Acoustical Performance
International Building Code
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
The current interest and growth of cross laminated timber (CLT) products has spurred interest in the manufacture of CLTs in the United States. The purpose of this paper is to explore the development of CLT materials from southern pine lumber commonly available in Virginia. A 5-layer CLT panel has been constructed using No. 2 southern pine lumber. Evaluation of mechanical properties, fire performance and acoustical performance were conducted. Results of these evaluations can guide the development and acceptance of CLT products in the International Building Code.
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52 records – page 1 of 6.