Cyclic performance of in-plane shear cross-laminated timber panel-to-panel surface spline connections

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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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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In-plane shear modulus of cross-laminated timber by diagonal compression test

BioResources ◽

10.15376/biores.14.3.5559-5572 ◽

2019 ◽

Vol 14 (3) ◽

pp. 5559-5572 ◽

Cited By ~ 1

Author(s):

Sven Berg ◽

Jonas Turesson ◽

Mats Ekevad ◽

Anders Björnfot

Keyword(s):

Shear Modulus ◽

Compression Test ◽

Pure Shear ◽

Shear Stiffness ◽

Least Square ◽

Compression Tests ◽

Plane Shear ◽

Cross Laminated Timber ◽

Fe Simulations ◽

Diagonal Compression

Cross-laminated timber (CLT) is an engineered wood material that is used in the construction industry, e.g., for floors, walls, and beams. In cases where CLT-elements are used as shear walls, the in-plane-stiffness is an important property. For non-edge glued CLT, in-plane shear stiffness is lower than for edge-glued CLT. To evaluate the non-edge glued CLT panel’s in-plane shear modulus, the diagonal compression test and finite element (FE) simulation was used. FE-models with both isotropic and orthotropic material models were used to calculate the shear stiffness. The FE models using pure shear loads were used as a reference to determine the correct value of the shear modulus. To verify the FE simulations, diagonal compression tests were conducted on 30 CLT samples. A calibration formula was derived using the least square method for calculation of shear modulus. The formula gave accurate results. The results showed that FE simulations can reproduce the same shear stiffness as tests of non-edge glued 3-layer and 5-layer CLT panels.

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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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