Evaluation of rolling shear modulus and strength of Japanese cedar cross-laminated timber (CLT) laminae

AbstractIn this study, the out-of-plane shear strength of hybrid cross-laminated timber (CLT) with outer layers of hinoki (hinoki cypress, Chamaecyparis obtusa) and inner layers of sugi (Japanese cedar, Cryptomeria japonica) is investigated for four different layer configurations. To investigate the influence from rolling shear properties of cross layers on the shear strength of CLT, stress analysis was conducted using the shear analogy method. The nominal shear strength, the maximum shear force divided by the cross-section of CLT, was in the 1.0–2.1 MPa range. Using the shear analogy method, the rolling shear modulus in the cross layer was determined as 72.9 MPa, which was comparable with the value obtained for laminae in previous study as well as the value confirmed by strain measurements in the present study. The magnitude of rolling shear stress in the cross layer was 0.9–1.1 times the average shear stress, which was negatively correlated with the nominal shear strength. From the regression line between the nominal shear strength and the magnitude of the shear stress in the cross layer, the mean shear strength of the cross layer was estimated to be 1.33 MPa.

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Effects of Grain Pattern on the Rolling Shear Properties of Wood in Cross-Laminated Timber

Forests ◽

10.3390/f12060668 ◽

2021 ◽

Vol 12 (6) ◽

pp. 668

Author(s):

Guofang Wu ◽

Yong Zhong ◽

Haiqing Ren

Keyword(s):

Shear Modulus ◽

Mechanical Performance ◽

Wood Products ◽

Rolling Shear ◽

Shear Moduli ◽

Factors Affecting ◽

Cross Laminated Timber ◽

Aspect Ratios ◽

Shear Property ◽

Pure Rolling

Rolling shear modulus and strength are the key factors affecting the mechanical performance of some wood products such as cross-laminated timber (CLT). As reported, rolling shear property strongly depends on the sawing pattern such as the aspect ratio and grain direction (grain mode). However, the mechanism behind this phenomenon has not yet been clarified. In this work, the rolling shear modulus and strength of spruce-pine-fir (SPF) with different grain modes and aspect ratios were experimentally investigated. In addition, a theoretical investigation was carried out to reveal the mechanism behind this phenomenon. The results exhibited that the rolling shear moduli of 0° and 90° grain-mode wood were the same. This value can be called the pure rolling shear modulus. Rolling shear modulus of wood with angles other than 0° and 90° can be calculated from the pure rolling shear modulus and grain angle. Therefore, this modulus can be called the apparent rolling shear modulus. Thus, using 0° and 90° grain-mode specimens to determine the pure rolling shear modulus and strength of wood is recommended.

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Influence of laminate direction and glue area on in-plane shear modulus of cross-laminated timber

SN Applied Sciences ◽

10.1007/s42452-020-03918-1 ◽

2020 ◽

Vol 2 (12) ◽

Author(s):

Jonas Turesson ◽

Zahra Sharifi ◽

Sven Berg ◽

Mats Ekevad

Keyword(s):

Finite Element ◽

Shear Modulus ◽

Compression Test ◽

Contact Area ◽

Tall Buildings ◽

Shear Stiffness ◽

Finite Element Simulations ◽

Plane Shear ◽

Cross Laminated Timber ◽

Diagonal Compression

AbstractThe use of cross-laminated timber (CLT) in constructing tall buildings has increased. So, it has become crucial to get a higher in-plane stiffness in CLT panels. One way of increasing the shear modulus, G, for CLT panels can be by alternating the layers to other angles than the traditional 0° and 90°. The diagonal compression test can be used to measure the shear stiffness from which G is calculated. A general equation for calculating the G value for the CLT panels tested in the diagonal compression test was established and verified by tests, finite element simulations and external data. The equation was created from finite element simulations of full-scale CLT walls. By this equation, the influence on the G value was a factor of 2.8 and 2.0 by alternating the main laminate direction of the mid layer from the traditional 90° to 45° and 30°, respectively. From practical tests, these increases were measured to 2.9 and 1.8, respectively. Another influence on the G value was studied by the reduction of the glue area between the layers. It was shown that the pattern of the contact area was more important than the size of the contact area.

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Low cycle fatigue tests and damage accumulation models on the rolling shear strength of cross-laminated timber

Journal of Wood Science ◽

10.1007/s10086-016-1547-6 ◽

2016 ◽

Vol 62 (3) ◽

pp. 251-262 ◽

Cited By ~ 9

Author(s):

Yuan Li ◽

Frank Lam

Keyword(s):

Shear Strength ◽

Damage Accumulation ◽

Low Cycle Fatigue ◽

Fatigue Tests ◽

Cycle Fatigue ◽

Rolling Shear ◽

Cross Laminated Timber

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Load Carrying Capacity of Drift Pin Joint of Cross Laminated Timber (CLT) with Steel Insert Plate

Wood Research Journal ◽

10.51850/wrj.2012.3.2.87-93 ◽

2017 ◽

Vol 4 (1) ◽

pp. 87-93

Author(s):

Shoichi Nakashima ◽

Akihisa Kitamori ◽

Kohei Komatsu

Keyword(s):

Japanese Cedar ◽

Longitudinal Direction ◽

Longitudinal Axis ◽

Maximum Load ◽

Tensile Tests ◽

Small Dimension ◽

Initial Stiffness ◽

Cross Laminated Timber ◽

The Difference ◽

Insert Plate

Cross Laminated Timber (CLT) is a structural plate element which is approved in Europe and is intended to be approved in Japan. It consists of small dimension laminae, in which laminae parallel and perpendicular to longitudinal direction are interlaminated. We performed tensile tests for the drift pin joint with steel insert plate. Specimen consisted of CLT was made from Japanese cedar laminae (thickness of laminae t = 30mm, five laminae were layered), with steel drift pin plate. Odd-numbered layers were parallel to the longitudinal axis, and even-numbered layers were perpendicular to the longitudinal axis. The experimental parameters were edge distances (3d, 4d and 7d), end distances (3d, 4d and 7d) and diameters of pin (12 and 16 mm) and the replication were three respectively. Initial stiffness was lower than the results of glulam drift pin joint loaded in parallel to the grain, however second stiffness after the yield of drift pin was higher because the lateral compression occurred at even-numbered layers. Additionally, ductility was higher because split failures around the pin were prevented by the glued effect of interlaminated layers. As the characteristic value of test results, initial stiffness K, yield load Py, maximum load Pmax, indicated the effect of the difference of the diameter of the pin, while deformation capacity indicated the effect of edge distance.

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Comparison of Theoretical and Laboratory Out-of-Plane Shear Stiffness Values of Cross Laminated Timber Panels

Buildings ◽

10.3390/buildings8100146 ◽

2018 ◽

Vol 8 (10) ◽

pp. 146 ◽

Cited By ~ 3

Author(s):

Jan Niederwestberg ◽

Jianhui Zhou ◽

Ying-Hei Chui

Keyword(s):

Shear Modulus ◽

Cross Section ◽

Single Layer ◽

Beam Theory ◽

Shear Stiffness ◽

Plane Shear ◽

Shear Moduli ◽

Cross Laminated Timber ◽

Highly Sensitive ◽

Out Of Plane

The lay-up of cross laminated timber (CLT) leads to significant differences in properties over its cross-section. Particularly the out-of-plane shear behavior of CLT is affected by the changes in shear moduli over the cross-section. Results from laboratory shear tests are used to evaluate the shear stiffness of 3- and 5-layer CLT panels in their major and minor strength direction. The results are compared to calculated shear stiffness values on evaluated single-layer properties as well as commonly used property ratios using the Timoshenko beam theory and the shear analogy method. Differences between the two calculation approaches are pointed out. The shear stiffness is highly sensitive to the ratio of the shear modulus parallel to the grain to the shear modulus perpendicular to the grain. The stiffness values determined from two test measurements are compared with the calculated results. The level of agreement is dependent on the number of layers in CLT and the property axis of the CLT panels.

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