Laminated Veneer Lumber Research Articles

Lateral loading behavior of the poplar LVL light wood shear wall

Poplar laminated veneer lumber (poplar LVL) is made of fast-growing poplar veneer and structural adhesive, which can well meet the developing requirement of the modern wood structures. This paper mainly focuses on the lateral loading behavior of the poplar LVL shear wall. For this purpose, six shear wall specimens with different opening types were fabricated and tested under the action of monotonic and cyclic loading. Performances were analyzed on the failure pattern, the load-displacement curve, the shear strength, the ultimate displacement, the elastic lateral stiffness, and the energy dissipation. To strengthen the corner joint, an innovative custom-designed hold-down was adopted, and the mechanical performance was also considered. The results showed that the failure of the specimen was mainly due to the yield of the nails and the separation between the stud and the base plate, while the hold-down can greatly improve the shear strength, the ultimate displacement, and the energy dissipation performance of the poplar LVL shear wall without openings. At last, the evaluation formula of the bearing capacity for the light wood shear wall is proposed so as to promote the theoretical basis for the application of poplar LVL in the light wood frame construction.

Effect of web openings on timber composite beams: Testing and analytical modelling

This study aims at evaluating effect of the web openings on the structural behaviour of the timber-timber-composite (TTC) beams. In total, twenty-two TTC beams (in eleven groups with two replicates of each group) were fabricated by connecting the CLT slab to laminated veneer lumber (LVL) or glued laminated timber (GLT) beams (webs) with or without openings. Effect of shape (square or circular) and size of the openings in the web, timber beam type (LVL or GLT), size of shear connectors (8- or 12 mm coach screws), continuity/discontinuity of the CLT slabs on the service stiffness, load carrying capacity and failure modes of the TTC beams were evaluated experimentally. Results of the tests were compared with additional bending tests performed on bare timber beams (without slab) to demonstrate effect of the slabs and coach screw shear connectors on the failure mode and peak load of the TTC beams with web openings. Lastly, an analytical solution to a Timoshenko composite beam was utilised to determine the distribution of shear force and bending moment between the timber slab and joist (web) and accordingly develop a mechanistic model for predicting the load carrying capacity of the TTC beams with web opening (and reinforcing effect of the screw shear connectors).

Bending Behaviour of Different Types of Timber I-Joist

Engineered wood I-joist is a structural system that comprises of flanges and web elements, and utilised as beams in buildings. Both elements must work together as a structural system to fit and meet the strength behaviour of a solid wood beam. The main objective of the study was to determine the bending strength behaviour of I-joist which produced from three types of jointed technique (finger, L-butt and nail plate) of oriented strand board (OSB) web element with two types of flange element (Keruing solid wood and laminated veneer lumber (LVL)). A total of 18 specimens of I-joist were tested to determine the bending behaviour, especially the modulus of elasticity (E) and modulus of rupture (MR). From the result of testing, LVL flanges specimen were obtained almost as strong as the specimens with solid wood flanges. Additionally, either solid wood or LVL flange was shown non-significant variances in bending strength behaviour because the MR values of the I-joist were insignificantly affected by flange element material. The I-joist specimen with finger jointed web was observed to be the strongest specimen when compared with other joints. Furthermore, the weakest joint among the three types of joints were fabricated with nail plate jointed web. The failures mode of the I-joist specimens were observed to fail due to tension or compression.

Withdrawal strength of hexagon head wood screws in laminated veneer lumber

Withdrawal strength of hexagon head wood screws in laminated veneer lumber

Development of a modified standard termite test for mass timber products

U.S. manufacturers are looking to expand the use of cross laminated timber panels (CLT) into the North American market, including states located in the southeast. However, there is no current assessment method for determining CLT vulnerability to the highly destructive native termites found throughout the U.S. The impact of these termites is particularly high in areas with suitable climate to their proliferation, such as the southeastern U.S. This study aimed to evaluate durability of CLT panels and to develop a laboratory assay to test susceptibility of this product to termites. Untreated CLT suffered mass loss of up to 43.8% in testing with an average visual rating of 7.2, indicating a moderate to severe attack with 10 to 30% of the cross-section of the product affected by termite intrusion.  Recommendations were developed for inclusion in standardized testing protocols and will be presented to standards organizations as appropriate. The proposed method can also be applied to evaluate termite resistance of other mass lumber products such as parallel strand lumber, laminated veneer lumber, and Glulam.

Ductility and Stiffness of Laminated Veneer Lumber Beams Strengthened with Fibrous Composites

The paper presents the results of experimental research on unstrengthened and strengthened laminated veneer beams subjected to 4-point bending. Aramid, glass and carbon sheets with high tensile strength (HS) and ultra-high modulus of elasticity (UHM) glued to external surfaces with an epoxy resin adhesive were used as reinforcement. Two reinforcement layouts were used: (1) sheets glued along the bottom surface and (2) sheets glued to the bottom and side surfaces. Based on the test results, the flexural strength, flexural ductility and stiffness were estimated. Compared to the reference beams, the maximum bending moment was higher by 15%, 20%, 30% and by 16%, 22% and 35% for the Aramid Fiber Reinforced Polymers (AFRP), Glass Fiber Reinforced Polymers (GFRP) and Carbon Fiber Reinforced Polymers (CFRP) HS sheets, respectively. There was no significant increase in the flexural bending capacity for beams reinforced with UHM CFRP sheets. Similar values of bending ductility indices based on deflection and energy absorption were obtained. Higher increases in ductility were observed for AFRP, GFRP and CFRP HS sheets in “U” reinforcement layout. The average increase in bending stiffness coefficient ranged from 8% for AFRP sheets to 33% for UHM CFRP sheets compared to the reference beams.

Bond behaviour between flax-glass hybrid fibre reinforced epoxy composite and laminated veneer lumber joints

In this paper, single-lap shear tests were performed to investigate the bond behaviour between flax-glass hybrid fibre reinforced polymer composite (HFRP) and laminated veneer lumber (LVL) joints. Epoxy was used as polymer matrix of the HFRP and adhesive to bond LVL and HFRP to be joints. Digital image correlation (DIC) technique was used to measure the strain distribution of the LVL-HFRP joints for determining their bond-slip relationship. The effects of fibre fabric sequence of the HFRP and bond length on average shear strength, maximum shear stress, bond-slip relationship and fracture energy of the LVL-HFRP joints were evaluated. The test results showed that the bond length had a significant influence on the average shear strength, i.e., as the bond length increased, the average shear strength of the joints decreased. The fibre fabric stacking sequence of HFRP also affected the bond behaviour of the joints significantly at a bond length of 200 mm. It was found that the specimens of LVL bonded with flax fabric layer of HFRP had higher average shear strength, maximum shear stress and interfacial fracture energy than the LVL joints bonded with the glass fabric layer of HFRP.

Engineering Wood Products from Eucalyptus spp.

Forest covers 4.06 billion hectares (ha) or 31% of the total land area worldwide, where 93% (3.75 billion ha) are natural regenerating forests and the remaining 7% (294 million ha) are planted forests. Eucalyptus spp., being one of the most important plantation species, has been planted in 95 countries around the world, and the area of plantation has exceeded 22.57 million ha. In the southern hemisphere, it is a significant industrial fast-growing tree species. These plantations serve as a valuable resource for the timber and fibre-based industries. Eucalyptus is the main fibre resource for the pulp and paper industries in developed countries. Timber extracted from the planted eucalyptus trees has long been used for solid wood and its fibres were used for manufacturing medium-density fibreboard. In comparison to most softwood species, Eucalyptus timber is reported to have a higher rigidity, making it ideal for manufacturing structural products. Therefore, this paper presents a review and analysis of the recent state of research on the utilisation of planted eucalyptus for engineered wood products (EWPs) manufacturing. This study investigated Eucalyptus-based EWPs such as particleboard, fibreboard, oriented strand board, laminated veneer lumber, plywood, glue laminated lumber, and cross-laminated lumber. The feasibility of using planted Eucalyptus in the production of EWPs, as well as the challenges encountered, was also discussed.

Integrative structural design of a timber-fibre hybrid building system fabricated through coreless filament winding: Maison Fibre

Coreless filament winding is a robotic fabrication technique in which conventional filament winding is modified to reduce the core material to its minimum. This method was showcased and developed through a series of pavilions demonstrating its potential to create lightweight structures. The latest project, Maison Fibre, goes one step further and adapts the fabrication into a hybrid structure combining fibre-polymer composites (FPC) with laminated veneer lumber (LVL) to allow for walkability. The result is the first multi-storey building system fabricated with this novel technique. During the integrative design process of the slab system, the optimum fibre layup was negotiated between the timber support span, load induction, boundary conditions, and material amount required. A total of four iterations of the hybrid component were load tested and compared with the maximum enveloped forces resulting from the global structural simulation. The full-scale load tests were used to calibrate the refined structural simulation of the slab components. The experimental process allowed for material reduction and validated the structural system's capability to withstand the design forces. In addition, the fibre layup was tailored and load adapted for the non-tested wall and slab components of the installation using the test results and achieving further material optimization. This publication describes the integrative design process of the hybrid slab system from initial concepts to the iterative optimization of the structural system, demonstrating its potential for future applications.

Timber-concrete composite structural flooring system

An integrated solution is presented for the execution of building structures using timber-concrete composite (TCC) sections that make efficient use of the mechanical properties of both materials. The system integrates flooring and shaped prefabricated beams composed of a lower flange of glued laminated timber (GLT) glued to one or more plywood or laminated veneer lumber (LVL) ribs and linked to an upper concrete slab poured in situ. The parts may be prefabricated in T shape (only one rib), in π shape (two ribs), or with multiple ribs to create wider pieces, thereby reducing installation operations.The basis of the system is the timber-concrete shear connection in the form of holes through the ribs, which are filled by the in situ-poured concrete. The connection is complemented with the arrangement of reinforcement bars through the holes.Three test campaigns were undertaken. Shear tests of the timber-concrete connection in 12 test pieces. Shear test along the wood-wood glue line (72 planes tested) and wood -plywood (24 planes tested). Delamination test of the glued planes (24 wood-wood planes and 8 wood-plywood planes). The results indicate a high strength joint, with ductile failure and high composite effect. Likewise, the shear test results along the glue line and the delamination tests show section integrity under demanding hygrothermal conditions.Preliminary sizing curves were developed considering the Gamma Method to evaluate the performance of the system. The results show the possibilities of the system, as pouring the upper slab concrete in situ makes it possible to create continuous semi-rigid joints between the elements. This gives rise to slender flooring structures, light and with high stiffness plane against horizontal forces.

Timber-timber composite (TTC) beams subjected to hogging moment

This study aims to investigate the structural behaviour of timber-timber composite (TTC) systems subject to hogging moment. A total of thirty-one TTC and six bare timber beam-to-column subassemblies (including fourteen replicates) were fabricated and tested to failure under hogging moment. The TTC beams were fabricated by connecting a cross laminated timber (CLT) slab to the top edge of a pair of laminated veneer lumber (LVL) or glued laminated timber (GLT) beams/joists. The effect of the CLT slab thickness, width, and orientation (i.e., loaded lengthwise or crosswise), column penetration in the CLT slab, bending moment to shear force ratio (span length), degree of shear interaction between the slabs and beams (controlled by the size of the shear connectors), and type of beams (LVL or GLT) on the structural performance of the TTC subassemblies were investigated experimentally. In addition, an analytical model was adopted for composite Timoshenko beams and modified to predict the stiffness and load carrying capacity of the TTC beams under hogging moment. The width of the CLT slab and column penetration in the slab (resulting in the reduction of the slab area of up to 20%) had minor (less than 9%) influence on the stiffness and peak load. However, the CLT slab thickness (in the range of 60–100 mm) had a major (up to 48%) influence on the peak load and stiffness of the TTC beam subject to hogging moment. The size of shear connectors (degree of shear connection provided by 8–12 mm screws) and orientation of the CLT slab had a moderate (max. 18–23%) influence on the load carrying capacity and stiffness of the samples.

Engineered Wood/Bamboo Laminated Composites for Outdoor Hydrophilic Platforms: Structural Design and Performance

Landscape designers increasingly prefer to use wood/bamboo-based composites for outdoor hydrophilic platforms owing to their natural surface texture, high performance, and sustainability to facilitate extensive interaction between people and water and enable the full range of ecological functions of water resources. In this study, four laminated composite (LC) structures were designed and manufactured using fluffed bamboo and wood veneers. Their surface textures, profile densities, water resistances, and mechanical properties were then evaluated. The type of fluffed veneer of the surface layer determined the texture of the LC surface. The specific structures of fluffed bamboo and wood veneer laminations were found to affect the LC profile density variability, water resistance, and mechanical properties owing to the differences in the strength and interfacial properties of bamboo and wood fibers. Finally, the water resistance and mechanical properties of all four LCs were found to be much higher than the highest level specified in GB/T 20241-2006 for ‘‘laminated veneer lumber’’ and GB/T 30364-2013 for “bamboo scrimber flooring”, indicating that they are promising materials for structures and flooring, particularly for outdoor hydrophilic platforms.

Investigation on Durability of Japanese Cedar (Cryptomeria japonica) Laminated Veneer Lumber

Investigation on Durability of Japanese Cedar (Cryptomeria japonica) Laminated Veneer Lumber

Особенности малоэтажного строительства Восточной Сибири

In this work, the issues arising during the construction of low-rise buildings in Eastern Siberia in 2021–2022 were addressed, including the changes associated with the special military operation and West-ern and the USA sanctions against Russia. Attention was paid to the characterisation of the main tech-nologies used in the construction of low-rise buildings. The necessity of using novel approaches to solving the problems associated with the implementation of engineering infrastructure facilities, in-tended as components of new low-rise construction projects, was substantiated. 90% of low-rise build-ings comprise private suburban wooden houses, most suitable for living in an area characterised by a harsh climate. Among the used construction materials, rounded logs, laminated veneer lumber, bricks, cellular concrete, and aerated concrete should be mentioned. Naturalness, environmental friendliness and low thermal conductivity are among the advantages of wooden constructions. Due to certain limita-tions of the regulatory framework in the construction industry associated with low-rise buildings, it is necessary to improve legislation in this area, as well as strengthen control over the quality of work. The main issues were addressed, including rising prices for construction materials, a reduction in incomes, a delay in obtaining a building permit, weak competition and a small number of modern equipment. The main trends in the development of low-rise construction, the potential of the modern construction in-dustry in Eastern Siberia, its prospects and modernisation were determined.

Feasibility of Mass Production of Laminated Veneer Lumber (LVL) from Japanese Cedar (Cryptomeria japonica) in Taiwan

Feasibility of Mass Production of Laminated Veneer Lumber (LVL) from Japanese Cedar (Cryptomeria japonica) in Taiwan

О работе составных двутавровых балок со стенкой из профилированного стального листа и поясами из однонаправленного клееного шпона

The article presents theoretical analysis of the performance of composite metal and timber I-beams with a wall of corrugated steel sheet and belts of laminated veneer lumber (LVL). Based on the classical theory of composite timber beams with compliance joints developed by P. F. Pleshkov and A. R. Rzhanitsyn, there has been derived the linear inhomogeneous differential equation of bending of composite beam made of corrugated steel, timber and timber-based materials. There are indicated the modules requiring of experimental determination of their values for this type of structures (namely, the joint stiffness coefficient, the reduced modulus of solid beam elasticity).

Evaluasi Perilaku Lentur Balok Tinggi LVL Sengon dengan Pengekang Lateral pada kedua Tumpuan

Slender beams (beams having a large section height to width ratio ( )) are commonly used in a structure that needs a large bending moment capacity. However, the use of slender beams in a structure is susceptible to overturning and torsion occurrence. Therefore, lateral bracing is usually placed in several points of the beam to prevent lateral-torsional buckling. In this study, a three-point bending test was conducted to evaluate the capacity of 250 mm x 50 mm x 2500 mm Laminated Veneer Lumber (LVL) beams made from Sengon. Two lateral supports were placed at both ends to prevent the beam's lateral displacement. The bending test result shows that the ultimate load of the LVL beam reach 27.88 kN before failure. Furthermore, the LVL beams' bending capacity was calculated using the mechanical properties provided by several previous studies. The LVL beam's capacity was predicted using manual calculation (based on SNI 7973: 2013) and numerical analysis. Numerical analysis was performed using ABAQUS software, and the results were evaluated using the Tsai-Hill and maximum strain failure criterion. The results showed that the maximum strain criterion provides a better prediction of the LVL beam's capacity than Tsai-Hill failure criterion.

Mechanical Behaviour of Aluminium-Timber Composite Connections with Screws and Toothed Plates.

This paper presents an investigation of the load-slip behaviour of aluminium-timber composite connections. Toothed plates with bolts are often used for connecting timber structural members with steel structural members. In this paper, toothed plates (C2-50/M10G, C2-50/M12G or C11-50/M12) have been used as reinforcement in aluminium-timber screwed connections for the first time. The push-out test specimens consisted of laminated veneer lumber slabs, aluminium alloy beams, and hexagon head wood screws (10 mm × 80 mm and 12 mm × 80 mm). Of the specimens, 12 additionally had toothed plates as reinforcement, while 8 had no reinforcement. The load carrying-capacity, the mode of failure and the load-slip response of the strengthened and non-strengthened screwed connections were investigated. The use of toothed plate connectors was found to be effective in increasing the strength of aluminium-timber composite connections and ineffective in improving their stiffness. The examined stiffness and strength of the connections can be used in the design and numerical modelling of aluminium-timber composite beams with reinforced screwed connections.

A nacre-inspired strong and flame retardant laminated veneer lumber bonded with magnesium oxychloride cement

ABSTRACT Laminated veneer lumber (LVL) is a novel artificial wood board that can make full use of small-diameter logs, however, problems such as low strength and inflammable property have limited its applications in architecture. Inspired by the “brick and mortar” structure of nacre, a new type of LVL was developed, in which magnesium oxychloride cement (MOC) was used as the substitute of traditional adhesives and D-gluconic acid sodium salt was employed as a water-resistant modifier. The resulting LVL displayed a higher strength and improved flame retardance, presenting modulus of rupture about 101 MPa, which was comparable to that of LVLs made by currently commercial adhesives. Simultaneously, these LVL boards remarkably suppressed the production of smoke and reduced the production of combustion heat, showing great potential in the application of the green architecture industry.

A Comparative Study on the Temperature Effect of Solid Birch Wood and Solid Beech Wood under Impact Loading.

In order to use wood for structural and load-bearing purposes in mechanical engineering, basic information on the impact behaviour of the material over a wide temperature range is needed. Diffuse porous hardwoods such as solid birch wood (Betula pendula) and solid beech wood (Fagus sylvatica) are particularly suited for the production of engineered wood products (EWPs) such as laminated veneer lumber (LVL) or plywood due to their processability in a veneer peeling process. In the frame of this study, solid birch wood and solid beech wood samples (300 × 20 × 20 mm3) were characterised by means of an impact pendulum test setup (working capacity of 150 J) at five temperature levels, ranging from −30 °C to +90 °C. The pendulum hammer (mass = 15 kg) was equipped with an acceleration sensor in order to obtain the acceleration pulse and deceleration force besides the impact bending energy. In both solid birch wood and solid beech wood, the deceleration forces were highest at temperatures at and below zero. While the average impact bending energy for solid birch wood remained almost constant over the whole considered temperature range, it was far less stable and prone to higher scattering for solid beech wood.