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

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.

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

Buildings ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 146 ◽  
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.

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

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.

Responses and capacity curves of mid- and high-rise wood buildings subjected to seismic excitations

2020 ◽  
Vol 47 (1) ◽  
pp. 63-76 ◽  
Author(s):  
S.C. Yang ◽  
H.P. Hong ◽  
F.M. Bartlett
Keyword(s):  
Pushover Analysis ◽  
Structural Members ◽  
Initial Stiffness ◽  
Seismic Excitations ◽  
Cross Laminated Timber ◽  
High Rise ◽  
Capacity Curves ◽  
Type Construction ◽  
Nonlinear Static ◽  
Gravity System

The design and modelling of 10-, 15-, and 20-storey wood buildings with cross-laminated timber and glulam structural members are presented in the present study. The system is platform-type construction with a cross-laminated timber core, perimeter walls as lateral load resisting system, and glulam columns as the gravity system. The designed buildings satisfy requirements stipulated in applicable design codes in Canada. The hysteretic models and the associated parameters used to model the fasteners for wood members are developed. Assessments of the nonlinear inelastic seismic responses and capacity curves of the designed buildings are carried out using the incremental dynamic analysis (IDA) and nonlinear static pushover analysis (NSPA) methods. The results indicate that the NSPA curve closely approximates the mean capacity curve estimated using the IDA curves for wood buildings. The post-yield stiffness ratio to initial stiffness for the wood buildings ranges from approximately 0.35 to 0.55. The results also show that the effect of the record-to-record variability on the IDA curves is substantial.

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

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.

Identification of the Out-of-Plane Shear Modulus of a 3D Woven Composite

2012 ◽  
Vol 53 (5) ◽  
pp. 719-730 ◽  
Author(s):  
R. Gras ◽  
H. Leclerc ◽  
S. Roux ◽  
S. Otin ◽  
J. Schneider ◽  
...  
Keyword(s):  
Shear Modulus ◽  
Woven Composite ◽  
Plane Shear ◽  
Out Of Plane

scholarly journals Violin varnish induced changes in the vibro-mechanical properties of spruce and maple wood

Holzforschung ◽  
2020 ◽  
Vol 74 (8) ◽  
pp. 765-776 ◽  
Author(s):  
Sarah Louise Lämmlein ◽  
Bart Van Damme ◽  
David Mannes ◽  
Francis Willis Matthew Robert Schwarze ◽  
Ingo Burgert
Keyword(s):  
Shear Modulus ◽  
Mode Shapes ◽  
Rectangular Plates ◽  
Layered Systems ◽  
Plane Shear ◽  
Modal Damping ◽  
Determination Process ◽  
Out Of Plane ◽  
Induced Changes ◽  
Contact Free

AbstractViolin varnishes are known to alter the longitudinal and radial material properties of violin tonewood. Here, the varnish-induced changes in the vibrational and elastic properties of spruce and maple wood were studied by modal analysis of rectangular plates. This contact-free investigation yields the eigenfrequencies and corresponding mode shapes and modal damping ratios of multiple out-of-plane modes. The longitudinal and radial E-modulus and the in-plane shear modulus were determined by an inverse material property determination process. The influence of traditional European varnish materials and different coating build-ups, comprising alcohol-based as well as oil-based varnishes, was studied during their application and for several months during drying and aging of the multi-layered systems. The evolutions of the changes induced by the different varnishes were rather similar and, except for modal damping, less pronounced for maple than for spruce. For the latter, the longitudinal E-modulus was slightly decreased while the shear modulus and radial E-modulus were increased after 18 months. The strong increases in modal damping ratios shortly after applying the coating systems (up to 150%) were reduced over time but remained significant for the time-span studied. However, also small differences between the influence of different coating systems and varnish materials on the amplitude of the induced changes became apparent.

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

BioResources ◽  
2019 ◽  
Vol 14 (3) ◽  
pp. 5559-5572 ◽  
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.

A Computerized Test Setup for the Determination of the In-Plane and Out-of-Plane Shear Modulus in Orthotropic Specimens

1991 ◽  
pp. 149-155
Author(s):  
D. Van Hemelrijck ◽  
L. Schillemans ◽  
F. De Roey ◽  
I. Daerden ◽  
F. Boulpaep ◽  
...  
Keyword(s):  
Shear Modulus ◽  
Plane Shear ◽  
Test Setup ◽  
Out Of Plane

scholarly journals Some of the Latest Active Strengthening Techniques for Masonry Buildings: A Critical Analysis

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1151 ◽  
Author(s):  
Elena Ferretti ◽  
Giovanni Pascale
Keyword(s):  
Stress Field ◽  
Static Analysis ◽  
Dynamic Load ◽  
Critical Analysis ◽  
Masonry Buildings ◽  
Load Bearing Capacity ◽  
Plane Shear ◽  
Out Of Plane ◽  
Active Confinement ◽  
Static Conditions

The present paper deals with the retrofitting of unreinforced masonry (URM) buildings, subjected to in-plane shear and out of-plane loading when struck by an earthquake. After an introductive comparison between some of the latest punctual and continuous active retrofitting methods, the authors focused on the two most effective active continuous techniques, the CAM (Active Confinement of Masonry) system and the Φ system, which also improve the box-type behavior of buildings. These two retrofitting systems allow increasing both the static and dynamic load-bearing capacity of masonry buildings. Nevertheless, information on how they actually modify the stress field in static conditions is lacking and sometimes questionable in the literature. Therefore, the authors performed a static analysis in the plane of Mohr/Coulomb, with the dual intent to clarify which of the two is preferable under static conditions and whether the models currently used to design the retrofitting systems are fully adequate.

Out-of-plane shear property analysis of Nomex honeycomb sandwich structure

2020 ◽  
pp. 073168442094328 ◽  
Author(s):  
Yue Liu ◽  
Wei Liu ◽  
Weicheng Gao
Keyword(s):  
Shear Strength ◽  
Shear Modulus ◽  
Sandwich Structure ◽  
Honeycomb Core ◽  
Plane Shear ◽  
Honeycomb Sandwich ◽  
Out Of Plane ◽  
Nomex Honeycomb ◽  
Analytical Expressions ◽  
Honeycomb Sandwich Structure

Honeycomb sandwich structure finds immense applications in aerospace manufacturing and other similar fields. The Nomex honeycomb sandwich structural material exhibits a complex structure and boundary conditions, making it difficult to obtain exact solutions for the equivalent out-of-plane shear modulus and shear strength of the Nomex honeycomb using current analytical methods. To this end, based on the energy method, the Kelsey model is simplified in this paper. Then, distribution of the shear forces in the longitudinal and transverse directions of the Nomex honeycomb core is analysed using the simplified model. Considering the effect of the wall thickness of the honeycomb core on the ultimate strength, the analytical expressions of the out-of-plane shear modulus and shear strength of the Nomex honeycomb are proposed. The shear properties and failure process of the Nomex honeycomb in two directions are then analysed experimentally. The accuracy of the analytical expressions of the equivalent shear modulus and shear strength is verified experimentally. The equivalent out-of-plane shear modulus and shear strength of the honeycomb was demonstrated to be effectively predicted by the analytical approach.

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