Fire Resistance of Cross-Laminated Timber Panels Loaded 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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Effects of knot area ratio on the bending properties of cross-laminated timber made from Korean pine

Wood Science and Technology ◽

10.1007/s00226-020-01255-5 ◽

2021 ◽

Author(s):

Sung-Jun Pang ◽

Kug-Bo Shim ◽

Keon-Ho Kim

Keyword(s):

Reference Value ◽

Major Axis ◽

Area Ratio ◽

Modulus Of Rupture ◽

Pinus Koraiensis ◽

Korean Pine ◽

Bending Properties ◽

Cross Laminated Timber ◽

Out Of Plane ◽

Layer Groups

AbstractThe effect of knot clusters on the bending properties of Korean pine (Pinus koraiensis) cross-laminated timber (CLT) was analyzed to increase the utilization of low-quality lumber. The laminae used to manufacture the CLT were classified into five groups, four major layer groups, and one minor layer group, by mechanical grade and knot area ratio (KAR) of the lamina. Out-of-plane bending tests were conducted on CLT made from each layer group. The modulus of elasticity (MOE) of the manufactured CLT was closely correlated with the MOE of each individual major axis lamina. In the case of the modulus of rupture (MOR) of the CLT, the KAR of the laminae used in the major axis layer was more significantly affected than the MOE. The main finding is that the lower fifth percentile MOR value of the CLT specimens with large knots (KAR > 0.5) was higher than the acceptable reference value of E3 grade CLT (ANSI/APA PRG 320) made from a similar lamina grade. Therefore, the use of low-quality lumber to manufacture CLT can be expanded under the condition of limitation of the greater KAR.

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

10.20944/preprints201809.0443.v1 ◽

2018 ◽

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 effected 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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A Review of the Methods for Predicting the Effective In-Plane Shear Modulus of Cross-Laminated Timber (CLT)

Advances in Civil Engineering ◽

10.1155/2021/6616559 ◽

2021 ◽

Vol 2021 ◽

pp. 1-15

Author(s):

Mehsam Tanzim Khan ◽

Ying Hei Chui ◽

Dongsheng Huang

Keyword(s):

Shear Modulus ◽

Structural Members ◽

Current Standard ◽

Load Bearing Capacity ◽

Plane Shear ◽

Cross Laminated Timber ◽

High Rise ◽

Out Of Plane ◽

Alternative Material ◽

Almost All

Cross-laminated timber (CLT) is a type of engineered wood product that offers both high in-plane and out-of-plane load-bearing capacity. It is slowly becoming an alternative material for building high-rise structures. However, there is no current standard or regulation for determining the shear modulus of CLT under in-plane loading condition, which is a very important property for its use as structural members. Few methods have been proposed over the last decade to determine the in-plane shear modulus of CLT. Almost all of the methods proposed until now have their strengths and weaknesses. In this paper, some of the prominent methods for determining the in-plane shear modulus of CLT are described and analysed. The descriptions along with the critical discussions will facilitate a better understanding and might pave the way to further enhancements of the method(s) to determine the in-plane shear modulus of CLT.

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