The process of bamboo-oriented strand lumber (BOSL) represents one of the best opportunities for automation, property control and consistency, and high utilization of material from abundant, fast-growing, and sustainable bamboo. In this study, BOSLs were prepared, with reference to the preparation process of bamboo scrimber, by compressing and densifying constituent units under the action of moisture-heat-force and resin polymerization, and then the effects of density variation on their physical and mechanical properties were investigated. The results revealed that the modulus of rupture, modulus of elasticity, compressive strength and shear strength of BOSL with density of 0.78–1.3 g/cm3 ranged from 124.42 to 163.2 MPa, 15,455 to 21,849 MPa, 65.02 to 111.63 MPa, and 9.88 to 18.35 MPa, respectively. The preparation of BOSL with bamboo as raw material could retain the good mechanical properties of natural bamboo, and produce bamboo-based structural products with different properties by controlling the density. The high strength of BOSL with high density was primarily due to the increased volume fraction of elementary fibers, the reduced porosity, and the enhanced gluing interface. The performance of BOSL can be comparable to, or surpass that of, wood or bamboo products. This study provided necessary basic research for the engineering design and application of BOSL.
The influence of selected technological aspects was studied relative to characteristics of oriented strand lumber (OSL) boards manufactured from pine strands. Six types of boards were prepared, differing in the strand fraction size, density (700 kg/m3 and 800 kg/m3), and adhesive used to glue the strands in the core layer. The adhesives compared were melamine-urea-formaldehyde (MUF) and polymeric diphenylmethane diisocyanate (pMDI). The results showed that the OSL boards had good physical and mechanical properties, even though pine strands of diverse characteristics, particularly in terms of their length and width, were used for their production. The influence of strand size was clear in the results of the bending and elongation tests. Both for the bending test and tensile strength in a direction parallel to the wood grain, the properties were on average 20% greater for boards made of larger strands compared to those made of smaller strands. However, the latter demonstrated greater internal bonding strength (IB). The weakness of OSL boards made from small strands was their low modulus of elasticity, particularly when the board density was simultaneously reduced.
The aim of this work is to investigate the effect of the fortification level of nanowollastonite on urea-formaldehyde resin (UF) and its effect on mechanical and physical properties of oriented strand lumbers (OSL). Two resin contents are applied, namely, 8% and 10%. Nanowollastonite is mixed with the resin at two levels (10% and 20%). It is found that the fortification of UF resin with 10% nanowollastonite can be considered as an optimum level. When nanowollastonite content is higher (that is, 20%), higher volume of UF resin is left over from the process of sticking the strips together, and therefore is absorbed by wollastonite nanofibers. The mechanism involved in the fortification of UF resin with nanowollastonite, which results in an improvement of thickness swelling values, can be attributed to the following two main factors: (i) nanowollastonite compounds making active bonds with the cellulose hydroxyl groups, putting them out of reach for bonding with the water molecules and (ii) high thermal conductivity coefficient of wollastonite improving the transfer of heat to different layers of the OSL mat, facilitating better and more complete resin curing. Since nanowollastonite contributes to making bonds between the wood strips, which consequently improves physical and mechanical properties, its use can be safely recommended in the OSL production process to improve the physical and mechanical properties of the panel.
Comprehensive guide to engineered wood construction systems for both residential and commercial/industrial buildings. Includes information on plywood and oriented strand board (wood structural panels), glulam, I-joists, structural composite lumber, typical specifications and design recommendations for floor, wall and roof systems, diaphragms, shear walls, fire-rated systems and methods of finishing.
An innovative multi-layer (3 and 5) composite laminated panel (CLP) with various layups were developed using sawn lumber and structural composite lumber (SCL) to address the rolling shear and gap issues of cross laminated timber (CLT). The bending properties including apparent and effective bending stiffness, shear stiffness, moment capacities and failure modes of CLPs were evaluated by a combination of modal tests and third-point bending tests of beam specimens cut from the panels. The static bending test results showed that the apparent bending stiffness values of 3-layer and 5-layer CLPs were up to 20% and 43% higher than the corresponding values of 3-layer and 5-layer generic CLT, respectively. The bending moment capacity values of 3-layer and 5-layer CLPs were up to 37% and 87% higher than the corresponding values of 3-layer and 5-layer generic CLT, respectively. The use of SCL in transverse layers eliminated the potential rolling shear failure in CLT and increased the stiffness properties. The apparent and effective bending stiffness predicted by shear analogy method had a good agreement with corresponding values measured by bending tests and/or modal tests. The prediction of bending moment capacity using shear analogy method cannot be validated due to the rolling shear failure and tension failure modes observed in certain groups.
Fifteen structural composite lumber (SCL) products including laminated-veneer lumber (LVL), laminated strand lumber (LSL), oriented strand lumber (OSL), and parallel strand lumber (PSL) provided by Boise Cascade, LP, West Fraser, and Weyerhaeuser were tested for moisture-related properties in this study, also covering four reference materials: 16-mm Oriented Strand Board (OSB), 19-mm Canadian Softwood Plywood (plywood), 38-mm Douglas-fir and lodgepole pine solid wood. Water absorption, vabour permeance, vapour sorption, and dimensional stability were measured with limited replication by following relevant standards for a purpose of assisting in improving building design and construction, such as hygrothermal modelling of building envelope assemblies, design for vertical differential movement, and on-site moisture management.
Overall moisture management during construction has become increasingly important due to the increase in building height and area, which potentially prolongs the exposure to inclement weather, and the overall increase in speed of construction, which may not allow adequate time for drying to occur. This report provides guidelines and relevant information about on-site moisture management practices that can be adapted to suit a range of wood construction projects. It aims to help designers and construction companies and builders assess the potential for moisture-related issues arising during the construction phase of a wood-building project and identify the appropriate actions to mitigate such risk.
In-plane shear and planar shear due to out-of-plane bending are important properties for the design of CLT-type floor systems. Properties of CLT-type panels are influenced by the orientation of the layer’s major stiffness directions and the properties of their layers. The layers are influenced by their characteristics, laminate aspect ratio, growth ring orientation and edge-gluing. In order to utilize the mechanical potential of CLT-type panels, it is necessary to understand the effects of layer and laminate properties on CLT performance. CLT and CLT-hybrid panels were tested in planar and in-plane shear tests. The shear properties were evaluated using static and modal test procedures, the accuracy of non-destructive test methods was evaluated. Relationships between specimen properties and the characteristics of laminates and layers, such as aspect ratio, growth ring orientation and edge-gluing, were established.
This guide provides the directives needed for designers of tall wood buildings to produce their designs, plans and specifications. It has been developed to give them the information and general concepts required, based on the selected system. The elements and details required to comply with the guidelines in this document must be incorporated from a project’s initial design phase.
Part 1 – Guidelines contains several sections, including one that deals with basic conditions and describes the minimum general conditions applicable to any project for the construction of a wood building exceeding 6 storeys. The following sections contain special provisions that specify and complete the basic conditions.
Acoustic emission (AE) characteristics of full-hole bolt-bearing testing on structural compositelumbers (SCL) including laminated veneer lumber (LVL) and oriented strand lumber (OSL) were investigated. The main conclusion is that AE cumulative counts vs time curves of the tested SCL in this study can be characterized with three distinct regions in terms of AE count rates: Region I with a lower constant count rate, Region II with varied and increased count rates, and Region III with a higher constant count rate. Differences in AE count rates of these three regions occurred between LVL and OSL. Also, within each tested SCL, differences in AE count rates were observed among the three regions. These differences in terms of AE count rates between two tested SCL indicate that different types of wood-based composites might have different AE characteristics in terms of the count rate changes when they are subjected to increased bolt compression load. In other words, these differences in AE characteristics between the two tested materials suggest AE “signatures” do exist for SCL bolt connections.
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