An exploratory study of composite cross-laminated timber (CCLT) made from bamboo and hemlock-fir mix

BioResources ◽  
2019 ◽  
Vol 14 (1) ◽  
pp. 2160-2170
Author(s):  
Peixing Wei ◽  
Brad Jianhe Wang ◽  
Libin Wang ◽  
Yongqi Wang ◽  
Guangrong Yang ◽  
...  
Keyword(s):  
Exploratory Study ◽  
Mechanical Performance ◽  
Western Hemlock ◽  
Bond Quality ◽  
Full Size ◽  
Cross Laminated Timber ◽  
Block Shear ◽  
Optimization Of Process Parameters ◽  
Dimension Lumber ◽  
Parallel Strand Lumber

This work investigated the feasibility of manufacturing composite cross-laminated timber (CCLT) from bamboo and a western hemlock and amabilis fir mix (hem-fir). Bamboo parallel strand lumber (bamboo PSL) was first fabricated as the surface laminae of CCLT. No. 2 and Btr 2×6 western hem-fir dimension lumber was imported from British Columbia (BC), Canada. The lumber was then sorted and further dried to form the inner laminae of CCLT. Multiple 800 × 800-mm CLT billets were fabricated using a commercial single-component polyurethane (PUR) adhesive. Block shear and delamination tests were conducted to examine the bond quality and durability of bamboo-wood CCLT. The results demonstrated that it is technically feasible to manufacture bamboo-wood CCLT with acceptable bond quality (shear strength, wood failure percentage, etc.) and delamination. Further studies should focus on the optimization of process parameters for manufacturing and surface treatment to improve the bond quality and durability and quantify the mechanical performance of bamboo-wood CCLT with a full-size production trial.

Evaluation of bond strength of cross-laminated LSL specimens under short-span bending

Holzforschung ◽  
2019 ◽  
Vol 73 (8) ◽  
pp. 789-795
Author(s):  
Meng Gong ◽  
Ling Li ◽  
Ying-Hei Chui
Keyword(s):  
Bond Strength ◽  
Test Procedure ◽  
Practical Interest ◽  
Adhesive Bond ◽  
Bond Quality ◽  
Block Shear ◽  
The Face ◽  
Great Practical Interest ◽  
Short Span ◽  
Mass Timber

AbstractMass timber panels (MTPs) have a great potential in the construction of mid- and high-rise buildings. Evaluation of the face-bond strength of MTPs is of great practical interest for this kind of products. This study aimed at developing an appropriate test procedure for evaluating the adhesive bond strength of cross-laminated laminated strand lumber (CL-LSL). Three-point short-span bending tests were conducted on two-layer asymmetric CL-LSL specimens (2LasymCL-LSL), which were adhesively bonded by two-component resins of the type polyurethane (PUR) or polyvinyl acetate (PVAc). For comparison, block shear specimens were tested as well. It was found that the 2LasymCL-LSL assembly was better suitable under the short-span bending for differentiating between good and poor bond quality of MTPs.

scholarly journals The influence of the opening size on the shear performance of the cross-laminated timber (CLT) walls

BioResources ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. 7071-7085
Author(s):  
Daiyuan Zhang ◽  
Liming Shen ◽  
Xudong Zhu ◽  
Sujun Zhang ◽  
Meng Gong
Keyword(s):  
Shear Strength ◽  
Mechanical Performance ◽  
Shear Stiffness ◽  
High Strength ◽  
Load Test ◽  
Static Load Test ◽  
Cross Laminated Timber ◽  
Wall Panels ◽  
Shear Performance ◽  
The Cross

Cross-laminated timber is a wood product with excellent fire resistance and mechanical performance that is often used in tiny houses. Using the ASTM standard E564, the shear performance of cross-laminated timber wall panels, with and without openings, were investigated in this study. The specimens were made of spruce-pine-fir IIc lumber and installed on a test platform using high-strength bolts passing through them. This connection mode limited the displacements obtained in the test, primarily the shear displacements and rocking displacements. By comparing the static load test data of the three specimens with openings and the one without an opening, it was found that openings reduced the shear strength and shear stiffness. For the same sized rectangular opening, the shear stiffness of the cross-laminated timber panel was less when the wider side was horizontal (normal to the direction of the applied force). The shear stiffness of the cross-laminated timber wall panels can be effectively improved by reinforcing the areas near the openings with metal sheets. With reinforcement, the shear strength did not change drastically, but the damage to the cross-laminated timber wall panels was significantly reduced.

Effect of Knots and Related Grain Deviation on the Rolling Shear in Dimension Lumber Used in Cross-Laminated Timber Transverse Core Layers

2019 ◽  
Vol 69 (1) ◽  
pp. 81-86
Author(s):  
Thibault Grandvuinet ◽  
Lech Muszyński
Keyword(s):  
Core Layer ◽  
Shear Capacity ◽  
Measurable Effect ◽  
Rolling Shear ◽  
Cross Laminated Timber ◽  
Three Point Bending ◽  
The Core ◽  
Loading Direction ◽  
Dimension Lumber ◽  
Product Standard

Abstract Cross-laminated timber (CLT) technology has the potential for utilization of lower grades and underused species of lumber, because the core layers perpendicular to the principal loading direction transfer loads through shear, which is not correlated to the grade of lumber. Currently the product standard specifies the minimum grade requirements for all lumber to be used as CLT laminations. In this study, the effect of the presence of knots in the transverse core layer of CLT billets was examined in matched CLT samples where the heavy presence of knots and the related grain disturbance in the transverse core layer were the only variables compared with knot-free reference. All samples were tested as short beams in three-point bending and all failed in rolling shear in the transverse core layer. The presence of knots had no measurable effect on the shear capacity or stiffness of the tested CLT beam samples.

Improvement of shear strength, wood failure percentage and wet delamination of cross-laminated timber (CLT) panels made with superheated steam treated (SHST) layers of larch wood

Holzforschung ◽  
2017 ◽  
Vol 71 (11) ◽  
pp. 873-879 ◽  
Author(s):  
Yeonjung Han ◽  
Yonggun Park ◽  
Yoon-Seong Chang ◽  
Hyunwoo Chung ◽  
Chang-Deuk Eom ◽  
...  
Keyword(s):  
Shear Strength ◽  
Dimensional Stability ◽  
Superheated Steam ◽  
Optimal Parameter ◽  
Wood Failure ◽  
Cross Laminated Timber ◽  
Pressing Time ◽  
Block Shear ◽  
Polyurethane Resin ◽  
The One

AbstractCross-laminated timber (CLT) panels – consisting of several cross-wise stacked layers of glued boards – have a high dimensional stability. However, the outer surfaces of CTL are exposed to environmental humidity changes and thus to swelling and shrinking. To improve CLT’s dimensional stability further, the layers of kiln dried (KD) CLT were substituted partly (on the surfaces) and entirely with superheated steam treated (SHST) wood. The effects of SHST wood and the performance of the one-component polyurethane resin (PUR) were tested by block shear and delamination tests after water soaking. Under various conditions, the shear strength ranged from 1.3 MPa to 4.7 MPa and the wood failure percentage (WFP) from 76% to 92%. The optimal parameter were ascertained as pressing time (30–45 min), pressure (0.98 MPa) and adhesive amount (175–200 g m−2). The water soaked delamination of CLT manufactured with SHST wood was approximately 50% lower than that of CLT made of KD wood.

scholarly journals Mechanical Properties of Innovative Multi-layer Composite Laminated Panels

2018 ◽  
Author(s):  
Jan Niederwestberg ◽  
Jianhui Zhou ◽  
Ying-Hei Chui
Keyword(s):  
Mechanical Properties ◽  
Failure Modes ◽  
Shear Failure ◽  
Mechanical Performance ◽  
Bottom Layer ◽  
Rolling Shear ◽  
Analogy Method ◽  
Aesthetic Appearance ◽  
Layer Composite ◽  
Dimension Lumber

Cross-laminated timber (CLT) possesses both good shape stability and the possible two-way force transfer ability due to its crosswise lamination. However, the transverse layers in CLT are prone to rolling shear failure under an out-of-plane load. An innovative multi-layer composite laminated panel (CLP) was developed by combining structural composite lumber (SCL) and dimension lumber to overcome the rolling shear failure while maintaining high mechanical performance and aesthetic appearance of natural wood. The mechanical properties of 5-layer CLP consisted of laminated strand lumber (LSL) and dimension lumber with different layups were evaluated by both static and modal tests. The results showed that the shear resistance, bending stiffness and moment resistance of CLP were up to 143%, 43% and 87% higher than their counterparts of regular CLT, respectively. The failure modes observed in both shear and bending tests indicated that the use of LSL in transverse layers could eliminate the potential rolling shear failure in CLT. With the lamination properties from components tests as inputs, the validity of shear analogy method was assessed by test results. The mechanical properties can be well predicted by shear analogy method except for the bending moment resistance of CLP and CLT with either rolling failure in the cross layer or tension failure in the bottom layer.

Mechanical performance of pre-fabricated metal dovetail connections for Cross-Laminated Timber (CLT) structures

2021 ◽  
Vol 303 ◽  
pp. 124468
Author(s):  
Zheng Li ◽  
Xijun Wang ◽  
Minjuan He ◽  
Zhan Shu ◽  
Yi Huang ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Cross Laminated Timber ◽  
Fabricated Metal
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