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When oil palm lumber is considered for load-bearing products such as glued laminated timber (GLT), defined strength and stiffness values are required. In this investigation, combined GLT from oil palm wood is tested in compression parallel and perpendicular and glulam lamellas in tension parallel to the vascular bundles. Strength and Young´s modulus in compression and tension parallel increase with the density by power law relationship. In contrast to dicotyle-dons, the strength in construction size exceeds that of small, defect-free test specimens (compression strength perpendicular), are in the same range (tensile and bending strength parallel) or only a little below (compression strength parallel). The specimen size does not influence the strength. The ratio of fc,0 : fm : ft,0 is 1.2 : 0.8 ... 1.7 ... 2.6 : 1 and fc,0 : fc,90 = 2.7 ... 13.0 ... 32.6 : 1 for ρ = 200 ... 400 ... 600 kg/m³; the ratio of Ec,0 : Em : Et,0 is 1.2 : 1.3 : 1 for ρ = 400 kg/m³. Ashby´s performance indices for minimum weight design rise with the density; the strength-density performance indices are comparable or only slightly lower than that for structural size softwood, whereas the modulus-density performance indices are much lower. The challenge in use of oil palm wood for load-bearing construction products is the low stiffness. [ABSTRACT FROM AUTHOR]

Deformation and surface-checking defects in wood are closely related to the drying stress caused by shrinkage and moisture content (MC) gradients throughout the drying process. In this study, 50-mm-thick Masson pine (Pinus massoniana Lamb.) lumber was used as the research object. The drying stress caused by shrinkage behavior and MC changes was monitored, and the development of surface checks was observed during the drying process. Results showed that when the average MC was 60%, the free water in the surface layer of lumber evaporated completely, causing the MC to decrease below the fiber saturation point (FSP). The surface layer was subjected to tension stresses, resulting in surface checks which primarily distributed in the latewood area and propagated longitudinally. When the average MC was between 30% and 40%, the combined effects of the high MC gradient and anisotropic shrinkage of the wood resulted in further expansion of the checks. As the average MC decreased to less than 20%, the MC of the core layer lumber decreased below the FSP, resulting in the closure or even disappearance of most surface checks. The critical point (average MC of 60%) of drying stress was obtained, which can benefit the fine-tuning of kiln-drying schedules and improve the drying quality of Masson pine wood. [ABSTRACT FROM AUTHOR]

Metal-plate-connected joints (MPC) are widely used in light timber buildings, while there are fewer studies on the joints under dynamic loads. For purpose of exploring a new possibility of application in bamboo structures, laminated bamboo lumber (LBL) and MPC have been incorporated in the current test. Four groups of metal-plate-connected tension joints using laminated bamboo lumber (LBL-MPC) are considered to be loaded by static and cyclic loading. Test specimens AA and AE refer to pairs of LBL member connected end-to-end in parallel, loaded in tension, connected with a rectangular shaped MPC oriented longitudinally (AA) or with the MPC oriented transversely (AE). Test specimens EA and EE refer to pairs of LBL members connected perpendicular, with a tension load on one of the members that imparts a perpendicular-to-grain loading on the other member. Both static and cyclic tests were performed using a displacement-controlled loading method with a loading rate of 1 mm/min. Under cyclic loading, the ultimate load of AA, AE, and EA joints was 7.6%, 10.4%, and 5.8% higher than that under static load, while EE joints were reduced by 6.4%. Two categories of skeleton curve models adapted to tensile joints of LBL-MPCs under cyclic loading were proposed. [ABSTRACT FROM AUTHOR]

Lumber recovery is an important parameter in determining the production efficiency and viability of mobile sawmilling operations. In this study, lumber recoveries for mobile sawmilling machines operating in four different locations in Tanzania were estimated. A total of 11 mobile sawmilling operations were studied. On each piece of mobile sawmilling machinery, data on log sizes, including bottom, mid and top diameter, and log lengths were recorded. Results showed that the number of logs per machine ranged from 5 to 40 with an average of 28 logs. The middle diameter of the logs ranged from 8 to 44.60 cm, with an average value of 20.58 cm. The number of lumbers produced for each log varied from 1 to 9 pieces, with an average of 3 pieces across all the sites. The lumber recovery (%), varied depending on the individual machine, machine type, source of logs and geographical site within Tanzania. For all the machines, the average lumber recovery (%) per machinery ranged from 16.15 to 62.79%. Among the three types of mobile sawmilling machinery, Wood-Mizer had relatively higher lumber recovery (56.2%) than Ameck and Ding-Dong. The overall average lumber recovery value for all the machines, irrespective of log sizes, site and source of lumber was 43.34%. Analysis of variance (ANOVA) indicated that site, source of lumber, machine type and size of logs had a statistically significant effect (p < 0.05) on lumber recovery (%). The study concluded that mobile sawmilling in Tanzania produces sawn timber with reasonable lumber recovery. However, further studies are recommended to examine technical aspects, such as productivity and taper, as well as cost of the mobile sawmilling operations. [ABSTRACT FROM AUTHOR]

Wood is a commonly used building material with numerous advantages over other construction products. However, in engineered wood products such as cross-laminated-timber and laminated veneer lumber moisture absorption can lead to decay, swelling, deformation, and glue line failures, diminishing their properties. Understanding moisture intrusion processes in these materials can aid manufacturers, engineers, and architects in developing effective moisture management strategies during and after construction. The porosity of CLT 3P sections was 56.5%, higher than CLT 2P sections at 36.8%. True density varied among species, with radiata pine, southern pine, and shining gum measuring 1358, 1411, and 1031 kg/m3, respectively. True density values for CLT 3P, CLT 2P, and LVL were 1202, 837, and 1406 kg/m3, respectively. The species and sample type significantly influenced porosity and density values, crucial for future moisture modelling and predicting moisture gain/loss during wetting and drying processes. Moisture sorption and desorption properties were examined for Australian timber species, CLT, and LVL at different temperatures. LVL samples exhibited higher moisture content and dimensional changes, possibly due to improved moisture transfer facilitated by lathe checks. CLT samples demonstrated greater anisotropic behaviours than those of LVL samples. The product type and sample type had significant effects on equilibrium moisture content values. [ABSTRACT FROM AUTHOR]

Ebony wood is often defective, showing severe cracks and deformations during manufacturing processes, and requires ample times for drying. The continuous drying has been proved to result in enormous collapses during the entire drying stage. In order to control the extent of collapses and further prevent these defects, a low temperature pre-freezing procedure was projected and followed by a cyclic drying program. This cyclic (intermittent) drying schedule was proposed based upon a so-called "mechano-sorptive creep gradient" (MSCG) strategy and elaborated by a "corresponding temperature differentia" (CTD) concept. The MSCG and CTD variables provided the theoretical explanation and the operational instruction to the cyclic drying test, respectively. The overall evolutions of collapse and transversal shrinkage of the ebony lumber boards were quantitatively investigated during the entire period of a cyclic drying process. Furthermore, the relationships between collapse and moisture content as well as cross section orientation were determined quantitatively. Under this specified pre-freezing plus cyclic drying method, the averaged collapse deformations were significantly decreased, with the maximum collapse variables accounting for 20 ∼ 30% of those under continuous cases, fully achieving the collapse controlling objective. [ABSTRACT FROM AUTHOR]

This study investigates the influence of different machining processes on the tensile shear strength of glued lumber, focusing on optimizing the tool geometry of face milling. The data obtained were analyzed using statistical methods. The roughness of the surface produced by the machining process and the damage to the microstructure under the cutting edge are identified as important factors influencing the quality of the bond. The results show that the optimized process (low roughness and microstructure damage) leads to more effective gluing. [ABSTRACT FROM AUTHOR]

The efficacy of bifenthrin-propiconazole preservative treatment of Dendrocalamus brandisii strips-based laminated bamboo lumber (LBL) was evaluated against fungal decay. The effect of preservative treatment on a few important physico-mechnical properties of LBL was also studied. The changes in chemical structure, microstructure and crystallinity of bamboo after exposure to fungi were studied using Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction analytical techniques. The treatment of bamboo strips with bifenthrin alone did not improve the decay resistance of LBL. A gradual reduction in percent weight loss was observed as the propiconazole concentration was increased indicating increased treatment efficacy. The mechanical properties namely MOR, MOE compressive strength parallel to fiber direction and glue shear strength were not much affected. The LBL prepared from 1.2% propiconazole and 3% bifenthrin-treated strips showed relatively lower changes in different functional groups and crystalline structure compared to untreated LBL after exposure to rotting fungi. The propiconazole-treated LBL did not show evidences of deep penetration of hyphae after exposure to both fungi. Hence, propiconazole-based formulations may be used to improve the decay resistance of LBL against fungal attack to class 1 without detrimental effects on physico-mechanical properties. [ABSTRACT FROM AUTHOR]

The effects of laminate configuration on mechanical properties were investigated for model glued-laminated timber (GLT) composed of single and mixed fast-growing tree species (Acacia mangium Willd., Maesopsis eminii Engl., and Melia azedarach L.), which were grown in community forests in Indonesia. The simulation of lamina yield was decreased in graded GLT compared with that in GLT with randomly designed, while the mean values of simulated dynamic Young's modulus (DMOE) in graded GLT were higher than those of GLT with randomly designed in each species. Graded GLT with mixed species should be produced to effectively utilize wood resources from fast-growing tree species. All mechanical properties showed higher values in single-species GLT especially for graded GLT, compared with solid lumber, suggesting that laminate configuration was effective for increasing mechanical properties. However, the factors that increase mechanical properties in single-species GLT differed among species. These factors can be evaluated by load-deflection curves. In GLT composed of single and mixed species produced with the same DMOE, almost all other mechanical properties were similar among laminate configurations. It is concluded that laminate configurations with different species and grades are useful for efficiently producing GLT with higher mechanical properties from multiple fast-growing tree species. [ABSTRACT FROM AUTHOR]

When assessing the strength of sawn lumber for use in engineering applications, the sizes and locations of knots are an important consideration. Knots are the most common visual characteristics of lumber, that result from the growth of tree branches. Large individual knots, as well as clusters of distinct knots, are known to have strength-reducing effects. However, industry grading rules that govern knots are informed by subjective judgment to some extent, particularly the spatial interaction of knots and their relationship with lumber strength. This case study reports the results of an experiment that investigated and modeled the strength-reducing effects of knots on a sample of Douglas Fir lumber. Experimental data were obtained by taking scans of lumber surfaces and applying tensile strength testing. The modeling approach presented incorporates all relevant knot information in a Bayesian framework, thereby contributing a more refined way of managing the quality of manufactured lumber. [ABSTRACT FROM AUTHOR]

Poplar laminated veneer lumber (LVL) offers many advantages such as high strength and small variability. This study explored the application of poplar LVL for making light timber trusses in China. A total of 12 poplar LVL truss joint specimens were designed and constructed, including truss support joints and ridge joints connected by bolts and tooth plates. The mechanical properties of the poplar LVL truss joints were experimentally tested and theoretically calculated. It was found that (1) the average bearing capacity of 10-mm bolted joints was 12.98%–22.62% higher than that of 8- or 12-mm bolted ones; (2) the average bearing capacity of ridge joints with 133 mm × 75 mm tooth plates was 23.03% and 28.22% higher than those with 152 mm × 75 mm and 152 mm × 50 mm tooth-plate connected ones; (3) the average bearing capacity of the bolted joints was higher than that of the tooth-plate connected ones when the shape of both joints were the same; (4) The damage of LVL dowel grooves and pull-out of tooth-plates from LVL were observed in the bolted and tooth-plate connected joints, respectively; and (5) The calculated values were, in comparation with the experimental results, were conservative for bolted joints and were in good agreement with the tooth-plate connected ones. [ABSTRACT FROM AUTHOR]

Localized damage may occur due to the fact that laminated bamboo lumber (LBL) has a lower compressive strength perpendicular to the grain direction than it does parallel to the grain. In this study, the transverse compressive performance of LBL under entire-surface compression and local-surface compression is investigated. Load–displacement curves, stress–strain relationship, detailed failure modes, and basic mechanical properties are obtained. The results show that despite the compressive strength and elastic modulus being nearly the same in the two transverse orientations, the failure patterns are distinct due to the layer structure. Ramberg-Osgood relation is utilized to fit the stress–strain curves. Proportional limit strength is determined indicating that specimens compressed locally have a greater load-bearing capability. Based on the finite element analysis and theoretical study, the mechanism of the enhancement in proportional limit strength is revealed. Equations for determining the bearing load of a specimen under local compression in the elastic stage are derived from the simulation data and logit model, considering the contact length and geometric size of the specimen. Additionally, parametric tests are conducted to determine the effect of bearing shape, bearing area, and loading mode on the stress distribution and bearing capacity. [ABSTRACT FROM AUTHOR]

Wood structure is becoming more prevalent than ever for the sustainability of civil engineering due to its green and renewable characteristics. The mortise-tenon joint is a traditional wooden connection but emerges with prominent advantages over that using metal connectors in the recycling process. This paper proposed a novel double-dovetail mortise-tenon joint, made of laminated veneer lumber, to connect cross-laminated timber (CLT) wall panels. The out-of-plane shear performance was investigated by monotonic and cyclic loading tests with a total of nine specimens in three groups. The failure modes, stiffness, strength and stiffness degradations, ductility and equivalent viscous damping ratios were discussed and analyzed. It was found that the dominant damage would transfer from the double-dovetail tenons to the CLT panels, when the ratio of the tenon head width to the panel thickness increased. In particular, the stiffness, maximum load and ductility of the joints decreased firstly and then showed an increase when the ratio increased from 0.6 to 0.67 and 0.75, respectively. The strength and stiffness degradations generally decreased when the ratio increased. In addition, the equivalent viscous damping ratio showed a transient fluctuation at the beginning, and increased with the damage accumulation, indicating more energy dissipation under seismic conditions. [ABSTRACT FROM AUTHOR]

This paper presents experimental results of the mechanical behaviour of LVL (Laminated Veneer Lumber) made of poplar reinforced with fiber reinforced polymer (FRP) subjected to shear and compressive stresses. Through mechanical properties such as strength, stiffness, maximum displacement and non-destructive measurements of elastic moduli in compression and shear, the influence of different variables was analysed: 1) Type of FRP (carbon or basalt); 2) Fiber direction; 3) Quality of veneer. The influence of veneer quality under compressive stresses and the difference between carbon and basalt under shear stresses have been verified. In addition, for the unidirectional carbon reinforcement, improvements up to 21% in compressive and shear stiffness and elastic modulus was achieved, respectively. [ABSTRACT FROM AUTHOR]

China's ban on commercial logging of natural forests coupled with increased, demand for log imports has caused the import prices of logs to fluctuate. It is important to explore the influence of the changing trend of imported log prices on the market price of wood products under the logging ban policy. Based on the data of 2013–2020, this paper uses breakpoint regression analysis to explore the market effect of import log price fluctuations under the natural forest logging ban in China. The results show that the change of log import price under the logging ban policy has led to the increase in market prices for wood products. Finally, based on the conclusion of the study, some suggestions are put forward from three aspects: broaden log import channels, adjust the management mode of resource reserves and optimize government subsidy policy. [ABSTRACT FROM AUTHOR]

This study demonstrates acetylation with acetic anhydride, one of the few industrial wood modification techniques on the market, to increase the dimensional stability and durability of laminated veneer lumber (LVL) made from beech wood (Fagus sylvatica L.). After being acetylated, veneers were hot-bonded to LVL using phenol-formaldehyde resin (PF) or phenol-resorcinol-formaldehyde resin (PRF). The bonding performance (bonding shear strength (BSS) and wood failure (WF)) was tested under the following three conditions: 20°C and 65% RH, water immersion, and rigorous boiling-drying-boiling cycle. Additionally, using the same specimen sizes on a second sample set, the moisture content (MC) and dimensional stability were determined. Results indicate that the PRF resin provided the strongest bonding performance on acetylated LVL and references. Acetylated LVL had higher BSS in wet conditions than untreated controls, especially after boiling in water, which could be attributed to less wood-water interaction at the cell wall level after acetylation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

While sawing logs along the pith to produce lumber, warps would occur in lumber due to the release of residual stress. Correction sawing should be performed to correct warps, so warps decrease the yield of lumber. Therefore, it is crucial to find a way to produce straight lumber without correction sawing. The present study focused on a series of high temperature drying with load, and it was confirmed that residual stress was eliminated, and warp was corrected after a series of high temperature drying with load. Besides, the optimal schedule conditions of high temperature drying were determined. After 6 months of storage, the treated lumber remained straight and residual stress in lumber did not recover. By applying high temperature drying with load to warped lumber, it is possible to dry lumber and correct the warps at the same time. [ABSTRACT FROM AUTHOR]

To study the feasibility and applicability of air energy assisted solar drying under low radiation value conditions in sub frigid zone regions, an intermittent air energy assisted solar heating (IAEASH) process was developed using the 100 Degrees Celsius Test Method and the controlled variable method. Experiments were conducted on two drying processes, namely, continuous air energy assisted solar heating (CAEASH) and IAEASH, using an air energy assisted solar drying system. Poplar sawn lumbers were used in the experiments. The drying processes of both CAEASH and IAEASH methods were compared and analyzed. Results showed that the effective heating time for IAEASH was reduced by 21 h compared to CAEASH, with an average of 23.9%/h increase in drying rate during effective heating. The average radial and tangential dry shrinkage strains of IAEASH during drying ranged from −0.011 to 0.048 and from 0.004 to 0.039 respectively, which were better than the experimental results of CAEASH, and reduced the shrinking of poplar lumber. The IAEASH dried lumber showed neater arrangement between cells. The power consumption of IAEASH was 314.5 kWh, which represented a 50.7% improvement in energy efficiency compared to CAEASH. In summary, the developed IAEASH process is feasible for application in sub frigid zone regions. [ABSTRACT FROM AUTHOR]

The relaxation of growth stress in trees from plantation forests of tropical areas is manifested in the quality of wood after the sawing and the relaxation of drying stress is expressed during the drying process, producing low wood quality. The present study aims to evaluate the lumber quality in logs by heating and steaming application before sawing as pretreatment to reduce growth stress and the application of steaming step during drying of Dipteryx panamensis (almendro) and Hieronyma alchorneoides (pilón) wood. The results showed that the variation of moisture content and drying rate concerning drying time in wood from logs steamed before or during drying led to a quick increase in the drying rate and a decrease in the moisture content. The steaming application to the logs or during drying decreased the incidence and magnitude of drying defects and increased the quality of dried lumber, especially bow, split, crook, and check defects. [ABSTRACT FROM AUTHOR]

The aim of this paper was to provide a better understanding of the mechanical behaviour of laminated-bamboo lumber nailed connection loaded monotonically. The specimens varied in nail diameter, edge distance of nail and loading angle to the grain. For edge distance less than six times the nail diameter (6d), the specimens failed prematurely at a lower load and exhibited moderate ductility behaviour. Two plastic hinges formed inside the side and core members, with crushing of the laminated bamboo lumber fibres, if the minimum construction requirements of nail edge distance were satisfied. It is found that the load increases significantly with the increase of nail diameter. Reductions in load-carrying capacity are witnessed with the increase in loading angle to grain, but the influence is small. The experimental results, such as stiffness and yield load, are compared against those predictions obtained from the existing design standards. A two-parameter theoretical model, related to the initial stiffness and yield load, is suggested to characterise the load-slip relationship of LBL nailed connections loaded monotonically, with the aim of deriving a mathematical relationship to represent this behaviour. There is a good agreement between the curves predicted by the theoretical model and the experimental results. [ABSTRACT FROM AUTHOR]

A timber bridge constructed in 1815 was renovated in 2018, wherein the load-bearing system was reinforced with beech laminated veneer lumber (LVL) elements. Beech LVL is primarily found in dry and heated structures (Service Class 1). Although the material of this bridge would not be directly exposed to weather, it would be exposed to outdoor relative humidity ranging between 50% in spring and 90% or higher in autumn (Service Class 2). Thus, the moisture content development in the reinforcements was monitored to observe the response of the material under such conditions. The moisture content was measured using both sorptive and electrical resistance methods. The relationship between the electrical resistance of the material to moisture content and sorption isotherms was determined through laboratory experiments. Thereafter, the derived relationships were used to determine the moisture content measured on the bridge over a period of two years. Consequently, the two measurement methods resulted in overlapping of moisture content values, which remained within safe levels and are expected to be maintained in future. The overlapping moisture content measurements validated that either of the monitoring methods could be independently deployed to obtain reliable results. [ABSTRACT FROM AUTHOR]

Partially threaded screws are essential fasteners in timber structures, and their use in combination with hardwoods is promising in order to obtain high-performance connections. Depending on the used wood species, the load-displacement behaviour and failure mechanisms of connections change, and, in particular for high-density species, brittle failures may occur more frequently with rather low ductility of the connection. Consequently, a good understanding of the mechanical behaviour of connections at different displacement levels helps to assess where previous rules reach their limits for hardwoods. The determination of all input parameters serves as a basis for a subsequent test programme on single-shear timber-to-timber connections using beech laminated veneer lumber, birch, spruce glulam and predrilled and non-predrilled partially threaded screws. Tests on connections with one screw and groups of screws are conducted, stopped at predefined displacement stages of 5, 10 and 25 mm, and opened. A comparison of the screw deformation at the different displacement stages reveals that non-linear connection behaviour is quite different in softwood and hardwood. Essential aspects of the analysis are particularities of the load-displacement behaviour, fastener spacing, ductility of connections and the progressive plasticising of the fasteners. [ABSTRACT FROM AUTHOR]

This paper presents a model for the efficiency evaluation of decision-making units comprising a network structure with undesirable intermediate measures. This model is then generalised to evaluate the efficiency of network decision-making units with triangular fuzzy data and undesirable intermediate measures. In this study, data envelopment analysis (DEA) models with fuzzy network structures and undesirable intermediate measures are considered and solved as linear triangular fuzzy planning problems. With numerical results, the application of the proposed model in the chipboard industry of wood lumber has been shown. [ABSTRACT FROM AUTHOR]

Wood properties, including Young's modulus, differ among clones in Larix kaempferi; however, available information is still limited on among-clonal variations of lumber qualities in L. kaempferi. The objectives of this study were to clarify the clonal variations in lumber quality and to identify the effects of juvenile wood on lumber quality in L. kaempferi. A total of 21 logs of 2.5 m in length were obtained from the trees of nine different plus clones of 57-year-old L. kaempferi trees. The logs were sawn into lumber, and the lumber was kiln-dried and planed into 38 × 89 mm in a cross-section. Lumber quality, such as bending properties, was determined. Significant differences were found in wood density, dynamic Young's modulus, modulus of elasticity, and modulus of rupture of the lumber among the nine clones. The highest repeatability was recorded in wood density. The lumber consisting of juvenile wood showed a lower lumber quality compared to the lumber consisting of mature wood. To produce lumber with a high quality from L. kaempferi, the clonal variation of lumber quality and the existence of juvenile wood should be considered. [ABSTRACT FROM AUTHOR]

Finger-joint is a technological process that uses small-dimension and low-quality lumber to obtain high-quality structural wood products. Curing time of an adhesive consists one of the most important factors on the final performance of finger-jointed wood. In this study, finger-jointed black pine (Pinus nigra L.) specimens were prepared to investigate the effect of finger length and adhesive type on the curing time of these assemblies, as specified by their static flexural properties. Two adhesive types (an emulsion polymer isocyanate and melamine-urea-formaldehyde adhesives), two finger lengths (12.5 and 20.0 mm) and four curing times (2.5, 7, 24 and 168 h) were used for this purpose. Statistical analysis results showed that finger length and curing time had a statistically influence on the bending behaviour of single finger-joint specimens. The necessary handling strength was attained between 7 and 24 h for the 12.5 mm specimens, while the 20.0 mm length finger-joints could be further processed after 2.5 h. [ABSTRACT FROM AUTHOR]

This paper positions three projects as intertwined extensions of the greater lifecycle of wood in construction. We consider each piece of wood we engage part of an ecosystem, and our use and application of those pieces a fleeting sequestration of a material. Whether repurposed lumber on a selected site, material deposited in a particular area, or a sacrificial matrix for future growth, the wood we use is borrowed for architectural construction, fabrication, and production temporarily, with an understanding that it emerged from our biological ecosystem, and it will ultimately return to it, serving as a nutrient that feeds future resources. [ABSTRACT FROM AUTHOR]

Certain important quality parameters of red maple (Acer rubrum) laminated veneer lumber (LVL) impregnated with three waterborne formulations: copper azole (CA-B), micronized copper azole (MicroCA or MCA) and alkaline copper quaternary (ACQ-D) bonded with phenol formaldehyde or cross-linked polyvinyl acetate (XPVAc) adhesives were evaluated. Pre-dipping of veneers before LVL production and two post-manufacturing procedures, viz., vacuum-pressure and post-dipping of LVL, were applied. Maximum copper retention in pre-dip-treated, vacuum-pressure and post-dip-treated LVL was 1.4, 9.7 and 1.7 kg/m3, respectively. Copper retention in MCA-treated LVL was relatively lower than soluble formulations. Various physical, mechanical and bonding properties of treated LVL such as density, water absorption, swelling, flexural properties, hardness, tensile shear strength, delamination and wood failure (%) were studied and compared with untreated LVL. Little to negligible deleterious effect was observed on properties of LVL due to these chemical treatments. Analysis of variance results showed that most of properties of red maple LVL were not significantly different compared with those of untreated LVL. Therefore, vacuum-pressure impregnation process can be used to treat the red maple LVL with novel micronized copper formulations for increasing the service life of such products against biodegradation without affecting techno-mechanical quality parameters. [ABSTRACT FROM AUTHOR]

Volumetric yield analysis is critical to optimizing performance in the timber industry. In the Amazon and in the Amapá state, this information is still little known and scarce, and therefore this study was developed to obtain and analyze the volumetric yield coefficient of ten commercial tree species and to test the variation by diameter class. We collect data of volumetric yield from for ten commercial species. For each species, the yields in different diameter classes were analyzed, as well as the yield difference between the species. The overall yield obtained for the sawmills (43.95%) and the yield of each species are within the established standards for operations in the industry according to the legal requirements. There were no differences (p ≥ 0.05) in diameter classes for species with the exception of Dinizia excelsa and Handroanthus albus. However, there was no linear increase (p ≥ 0.05) between the diameter and yield of lumber for all species. The species Dinizia excelsa, Hymenolobium petraeum, Ocotea rubra and Vochysia guianensis show a significant difference in yield for the other species due to the higher obtained values, however, they are statistically similar when compared to each other. [ABSTRACT FROM AUTHOR]

The knowledge of moisture content (MC) and drying stress are crucial parameters to control the drying process and maintain the quality of dried wood. Herein, we investigated the pattern of moisture transfer and stress development in Chinese fir during the high-temperature drying process. The MC in each layer of lumber was separated into bound water and free water via nuclear magnetic resonance (NMR), and the drying and residual stress were measured using prong test method. There was different MC in each layer along the thickness, resulting in an MC gradient that initially increased and then decreased, which is consistent with the trend of drying stress. The T21 peak indicating bound water shifted to the left especially when MC was below the fiber saturation point, signifying that the discharge of moisture became difficult with prolonged drying time. The ratio of bound water to free water was different in each layer, indicating that the moisture transfer was different along the thickness. Furthermore, the residual stress was greater than the corresponding drying stress though the disparity reduced gradually, which suggests that the MC gradient was the largest affecting factor for drying stress at high MC stages but decreased to some extent as the drying process continued. [ABSTRACT FROM AUTHOR]

The paper presents a truss concept characterised by structural simplicity and economic efficiency. The intended materials are spruce glulam for chords as well as posts and beech LVL (laminated veneer lumber) for diagonals, which are stressed in tension. Connections between the truss members are preferably be realised using self-tapping screws. The main focus of the paper is on a newly developed diagonal connection where the diagonals are screwed on to both outsides of the chords with countersunk screws and special washers. For this diagonal connection, a calculation model of the load-bearing capacity and the connection stiffness is presented. Tests were performed which encompass local and global stiffness examinations between screwed-on beech LVL diagonals and chords even for technically different screw connections. The corresponding test results agree with analytical values according to the proposed calculation model. A corresponding small-scale truss prototype was designed and tested. Computer-aided analyses of the truss deformations give first evidence for the actual feasibility of the truss concept employing the newly developed connection. [ABSTRACT FROM AUTHOR]

The aims and objectives of this study were to investigate the potential to predict laminated veneer lumber (LVL) stiffness from wood properties measured on trees and logs, and determine variation in log, wood and veneer properties as a function of tree height and age. Log selections were made from trees in three stands that were planned for harvesting at 14, 20 and 21 years of age. Rotary peeled veneer recovery from the logs was on average 65%. After drying, Metriguard testing showed over 50% of the veneer had an estimated dynamic modulus of elasticity (MOEdyn) above 12 GPa, with 20% above 14 GPa, and that veneer from the second log by tree height had higher MOEdyn values. In visual assessment to the AS/NZS 2269.0:2012 Standard, no veneer could be utilised in a panels face or subface positions and the older-age stand provided almost four times the volume of usable veneer. Standing-tree acoustic wave velocity (AWV) explained a moderate amount of variance in log MOEdyn and Pearson correlation coefficients between the (Metriguard) veneer MOEdyn, log AWV, log MOEdyn and disc basic density were significant, positive and strong, with log AWV explaining most of the observed variance in log stiffness. A moderately strong and positive linear regression existed between log AWV and veneer MOEdyn, supporting the use of log AWV tools for the ranking of stiffness in fibre-grown plantation E. nitens logs. Mechanical strength testing of LVL studs extracted from panels manufactured from the trial's veneer indicated they equalled, and for some tested parameters exceeded, the characteristic design strength values previously published by commercial LVL manufacturers for equivalent size pine products. [ABSTRACT FROM AUTHOR]

Innovative beech laminated veneer lumber (LVL) circular hollow sections for the use as temporary geotechnical soil nailing systems are currently being developed. Due to the permanent subsoil cement embedment, combined with high water saturation and permanent loading, the timber sections will lose strength and stiffness over time to a degree currently unknown. This paper presents the tensile and bending material properties of flat and curved beech LVL under various periods of immersion in a water–cement grout solution aiming at inducing both water saturation and long-term alkaline attack of the timber. In total, 824 and 279 samples were tested in tension and bending, respectively. Results show that samples manufactured from 3 mm thick veneers result in tensile strength and stiffness 17% and 24% higher, respectively, than samples manufactured from 2 mm thick veneers. A reduction in the initial bending and tensile strength of up to 70% was found after 90 days of water saturation and cement contact. Taking into account a duration of load factor for permanent loading of two years, it is recommended to reduce the short-term tensile and bending strength of beech circular hollow sections to be used as geotechnical anchors by 80%. [ABSTRACT FROM AUTHOR]

Wood products that are subjected to sustained stress over a period of long duration may weaken, and this effect must be considered in models for the long-term reliability of lumber. The damage accumulation approach has been widely used for this purpose to set engineering standards. In this article, we revisit an accumulated damage model and propose a Bayesian framework for analysis. For parameter estimation and uncertainty quantification, we adopt approximation Bayesian computation (ABC) techniques to handle the complexities of the model. We demonstrate the effectiveness of our approach using both simulated and real data, and apply our fitted model to analyze long-term lumber reliability under a stochastic live loading scenario. Code is available at . [ABSTRACT FROM AUTHOR]

Most research regarding revenue management in manufacturing has considered only a short-term planning horizon, assuming supply and production data exogenously given. Motivated by the case of the Canadian softwood lumber industry, this paper offers additionally a medium-term visibility for firms with limited capacity and faced with seasonal markets. We propose a demand management process for Make-To-Stock environments, integrating sales and operations planning (S&OP) and order promising based on revenue management concepts. Given heterogeneous customers, divergent product structure and multiple sourcing locations in a multi-period context, we first define a multi-level decision framework in order to support medium-term, short-term and real-time sales decisions in a way to maximize profits and to enhance the service level offered to high-priority customers. We further propose a mathematical formulation integrating an S&OP network model in the Canadian softwood lumber industry and an order promising model using nested booking limits. This new formulation allows reviewing previous order promising decisions while respecting sales commitments. A rolling horizon simulation is used to evaluate the performance of the proposed process in various demand scenarios and provides evidence that better performances can be achieved compared to common demand management practices by integrating S&OP and revenue management concepts. [ABSTRACT FROM AUTHOR]

Accurate estimates of lumber volume become an important indicator of production and monetary value for a sawmill. However, such estimates are only obtained directly after logging, and no accurate predictions are made for the Amazonian commercial species. In this sense, the objective was to generate equations of lumber volume for commercial species in Amapá (a state in northern Brazil) by adjusting and selecting regression models. The data of 50 logs processed from 10 commercial species were collected, as well as the quantity and volume of sawn products. Sixteen (16) statistical models were adjusted and statistical weights were performed to evaluate the quality of the estimates and to select the best equation by species. In summary, precise estimates of lumber volume can be obtained by the nº16 model for Carapa guianensis, while the models nº13 and nº15 are the most recommended for Dinizia excelsa and Hymenolobium petraeum, respectively. Model 7 presented the best adjustments for Hymenaea courbaril and Vochysia guianensis. Equations using only the log diameter variable suggest less precise estimates. Also, the log volume should be considered as an important predictor variable to obtain the serrated/lumber volume for the different Amazonian commercial species. [ABSTRACT FROM AUTHOR]

Wave propagation techniques based on ultrasound for timber grading are influenced by the moisture content (MC) of wood. The ultrasound velocities at an equilibrium MC (V12) and above saturation point (Vsat) were used to calculate moisture-related adjustment factors (kH). Tests were conducted using plantation hardwoods (Corymbia citriodora, Eucalyptus grandis and Eucalyptus pellita) grown in Brazil. Below the fiber saturation point (FSP), kH values were between 0.66% and 0.83%, which concurred with intervals proposed in existing literature for softwoods. However, the kH inferred from the velocities obtained at MCs above the FSP increased (from 10% to 30%) with increasing density. The sound velocity under saturated conditions (Vsat) obtained by adjustment equations was 2-9% lower than the actual Vsat obtained from the tests. The obtained adjustment factors may be useful for the standardization of nondestructive timber grading based on ultrasound propagation. [ABSTRACT FROM AUTHOR]

The drying kinetics of poplar lumber was experimentally investigated as a function of drying temperature (115, 135, 160, 185 and 205°C) during a periodic hot-press-drying process. Poplar lumber was dried under contact (compression ratio of 10%) and high-press states (compression ratio of 44%). Compared with the contact-state, the high-press-state showed higher drying rate and higher efficiency of removing free water than bound water in wood. Eight mathematical models from the literature were established to analyze the drying behavior. The Weibull model, with an average determination coefficient R2 of 0.9958, fitted well for all applied drying conditions. The scale parameter decreased with increasing drying temperature and was lower for high-press-state drying compared with that for contact-state drying. Moisture diffusivity and activation energy were calculated according to the Weibull model. Diffusivity increased with increasing drying temperature, with the average value of 1.734 × 10-6 and 3.313 × 10-6 m2/s and activation energy of 34.79 and 32.85 kJ/mol for contact-state drying and high-press-state drying, respectively. Hot-press drying created an M-shaped curve of density distribution, with high density at the two surface regions gradually decreasing toward the core region. The contact state-dried wood showed increased density near the wood surface. Both average density and peak density improved in the case of high-press-state-dried wood. Furthermore, the hydrophilic index of wood for high-press-state drying was lower than that of the contact-state drying, and the opposite was true regarding crystallinity index. The hygroscopicity of high-press-dried poplar decreased with lower equilibrium moisture content and higher moisture excluding efficiency, compared with contact-state-dried poplar. The rapid, high-quality drying of poplar lumber through periodic hot-press was more potentially achieved by the high-press-state compared with contact-state drying. [ABSTRACT FROM AUTHOR]

Faster growth and reduced harvesting ages are causing a reduction in the stiffness of lumber from South African grown pine plantations. The objective of this study was to determine whether increased planting densities of Pinus elliottii would result in improved stiffness of its sawn lumber and whether it would affect other relevant lumber properties. Four planting density treatments (403, 1 097, 1 808, and 2 981 stems ha−1) of a 12-year-old experimental spacing trial were processed into lumber. The static modulus of elasticity (MOEstat), modulus of rupture (MOR), warp, knot properties and density of the lumber were measured for 172 boards. Results showed that the planting density had a significant effect on the MOEstat of the lumber. The higher mean MOEstat (up to 27% increases) of lumber from densely planted trees seems to be the result of the higher slenderness and the slower diameter growth of these trees. Planting density also had a significant effect on the twist, knot area ratio and the number of knots per board. The magnitude of the effect on each of these properties, however, was relatively low. [ABSTRACT FROM AUTHOR]

To protect against decay and fungal invasion into thewood, the micronized copper, copper carbonate particles, has been applied in the wood treatment in recent years; however, there is little information on the health risk associated with sanding micronized copper-treated lumber. In this study,wood dust from the sanding of micronized copper azole-treated lumber (MCA) was compared to sanding dust from solubilized copper azole-treated wood (CA-C) and untreated yellow pine (UYP). The test found that sanding MCA released a much higher concentration of nanoparticles than sanding CA-C and UYP, and the particles between about 0.4-2 μm from sanding MCA had the highest percentage of copper. The percentage of copper in the airborne dust fromsanding CA-C had aweak dependency on particle size and was lower than that from sanding MCA. Nanoparticles were seen in the MCA PM2.5particles, while nonewere detected in theUYP or CA-C. Inductively coupled plasma mass spectrometry (ICP-MS) analysis found that the bulk lumber for MCA and CA-C had relatively equal copper content; however, the PM2.5 particles from sanding the MCA had a higher copper concentration when compared to the PM2.5 particles from sanding UYP or CA-C. The cellular toxicity assays showthat exposure of RAW264.7 macrophages (RAW) to MCA and CA-C wood dust suspensions did not induce cellular toxicity even at the concentration of 200 μg PM2.5 wood dust/mL. Since the copper from the treated wood dust can leach into the wood dust supernatant, the supernatants of MCA, CA-C and UYP wood dusts were subjected to the cellular toxicity assays. The data showed that at the higher concentrations of copper (≥5 μg/ml), bothMCA and CA-C supernatants induced cellular toxicity. This study suggests that sanding MCA-treated lumber releases copper nanoparticles and both the MCA and CA-C-treated lumber can release copper, which are potentially related to the observed in vitro toxicity. [ABSTRACT FROM AUTHOR]

Twelve-year-old Japanese larch (Larix kaempferi[Lamb.]Carr.) trees of 20 different progenies and/or provenances were sampled at one site in the Mauricie region of Quebec. Two standard samples were obtained at breast height and closer to the bark from each tree. Partial and total radial, tangential, and volumetric shrinkages, and tangential/radial (T/R) shrinkage ratios were assessed. All of these variables were significantly affected by the progeny/provenance. Drying defects are one of the main reasons for downgrading larch lumber; thus,T/Rshrinkage ratio was considered for the selection of progenies/provenances for lumber production purposes. Lowest partial and totalT/Rshrinkage ratios were obtained with progenies/provenances 8964, 8904, 8962, 8957, 8907, 8927, 7283, and 7795. Among them, lowest partial and total tangential, radial, and volumetric shrinkages were found in progenies/provenances 8964, 8962, and 8907 as well. Other physico-chemical (mechanical properties, density, extractive content) and silvicultural (growth rate) attributes should also be taken into consideration for an adequate selection of progenies/provenances according to the specific final utilization. [ABSTRACT FROM AUTHOR]

The pacific coast hemlock or “hem-fir” is a dominant species mix in British Columbia that is difficult to kiln-dry; hence, many mills are quite conservative with their drying schedules. Furthermore, mills tend to dry hem-fir with no green moisture content presorting, thus promoting high moisture differences within and between dried timbers. In this study, application of green chain moisture-based sorting, coupled with a modified drying schedule, was considered to be a potential way to improve drying times, moisture content spreads, and lumber quality. Modified schedules coupled to three-group green moisture content presorting, i.e., mixed, low, and high, were compared to a standard industrial one. To evaluate the process and product quality, final moisture content variation between and within lumbers, drying rates, warp, surface and internal checks, shrinkage, and casehardening were assessed. Data analysis revealed that there was no significant difference between the drying runs in terms of final moisture content variation, except in the high initial moisture content group. In regard to the sorting, high initial moisture content sorting helped to reduce the final moisture content variation. In particular, the modified schedule, when there was a high initial moisture content sorting, did improve the uniformity of final moisture content in comparison to the industrial one. [ABSTRACT FROM PUBLISHER]

Laminated strand lumber (LSL) and laminated veneer lumber (LVL) were thermally modified as a posttreatment at 140°C, 150°C, 160°C, 170°C, and 180°C. The tension modulus of elasticity (MOE) of LSL was not significantly impacted by the treatments, with the 180°C treatment group exhibiting the highest tension MOE (11.8 GPa). The LVL also experienced minimal impacts, with the 150°C treatment group having the highest tension MOE (19.4 GPa) and the 160°C treatment group exhibiting the lowest (17.1 GPa). The maximum tensile strength (MTS) of the LSL and LVL significantly decreased with increasing temperatures, with the control and 180°C treatment groups experiencing the highest and lowest MTS, respectively. The lowest MTS for LSL was 10.8 MPa (180°C treatment), which was 70% lower than the controls. The lowest MTS of the LVL was 24.4 MPa (also at the 180°C treatment), which was a 49% decrease compared to the controls. These results suggest that thermal-modification posttreatments minimally impact tension MOE, but can significantly reduce MTS at higher treatment temperatures. Combined with previous work improving the moisture properties and equilibrium moisture content of thermally modified LSL and LVL, it may be possible to optimize the treatment technique(s) to yield products with desirable properties. [ABSTRACT FROM AUTHOR]

Estimation of lumber yield from a forest inventory is important in determining the optimal utilization of available regional wood supply. In this study, we review existing approaches of lumber yield estimation, including knowledge-based empirical board-foot log rules used in the United States and some regions of Canada, survey-based wood conversion factors, and optimization technology-based computer simulations. Lumber yields estimated from different approaches are then compared using six datasets from a white spruce commercial thinning experiment in Alberta, Canada. Our results indicated that (1) estimated lumber yield can be significantly different when different methods are employed; (2) board-foot log rules often underestimate lumber yield; (3) wood conversion factors represent regional average of lumber yield as a constant and thus are unsuitable for forest inventory-based lumber yield estimation; and (4) optimization technology-based computer simulations can provide the best estimate of lumber yield for a given forest inventory as long as the mill conditions and lumber dimensions from market demand are specified. Forestry investment in applying computer simulation methods should be encouraged in sawmill operations to improve lumber yield and enhance environmental protection, because, for a given amount of lumber, improving lumber yield means reduced demand for harvest operations. [ABSTRACT FROM AUTHOR]

Profit-driven order promising mechanisms have been receiving increasing attention from academia and practitioners in recent years. In spite of the recent advances in the field, its application in practice still remains a challenge. One of the most interesting approaches currently discussed is called aATP (allocated available-to-promise). In this paper, we propose some advances for current state-of-the-art aATP constructions in make-to-stock environments, mainly adapting it to commodity products sold through spot markets. Practical situations are tested through simulations supported by real data obtained from a major softwood manufacturer in Canada. Examples show that the proposed approach can increase the profitability of the producer. [ABSTRACT FROM AUTHOR]

Although sustainable forest management is accepted worldwide in concept, challenges in the methods of implementation remain. Using local data sets from Alberta, Canada, we show that a simulation approach can assist the implementation of sustainable forest management by improved understanding of product potential and other forest ecosystem goods and services that forests can provide for a given forest inventory. This will assist facilitating trade-offs among them for an optimal wood utilization strategy to achieve sustainable forest management. In this example, effects of wood utilization standard on merchantable volume, lumber volume, and number of trees that can produce at least one piece of lumber are quantified, and a conversion method for wood volumes under different wood utilization standards is presented. Wood utilization standard is the combination of stump height and diameter inside bark at merchantable height, which considerably influences available volume quantity of forest resource. However, such influences have not been quantified for sustainable forest management implementation. Our results not only confirmed that merchantable and lumber volumes increased with decreasing stump height and diameter inside bark at merchantable height, but also revealed that this trend will not hold when diameter inside bark at merchantable height is less than 7 cm. [ABSTRACT FROM AUTHOR]

This article presents a joint distribution for the strength of a randomly selected piece of structural lumber and its observable characteristics. In the process of lumber strength testing, these characteristics are ascertained under strict grading protocols, as they have the potential to be strength reducing. However, for practical reasons, only a few such selected characteristics among the many present, are recorded. We present a data-generating mechanism that reflects the uncertainties resulting from the grading protocol. A Bayesian approach is then adopted for model fitting and construction of a predictive distribution for strength that accounts for the unrecorded characteristics. The method is validated on simulated examples, and then applied on a sample of specimens tested for bending and tensile strength. Use of the predictive distribution is demonstrated, and insights gained into the grading process are described. Details of the lumber testing experiments can be found in the online supplementary materials. [ABSTRACT FROM AUTHOR]

The objective was to study the effect of the drying time and moisture content variations on the drying rate during kiln drying. The moisture content is a good predictor of the variation in drying rate; to determine the drying rate, the model DR =a * t + b (where DR is the drying rate, t is the drying time, and a and b are constants) was used. Cordia alliodora, Dipterix panamensis, Hieronyma alchorneoides, and Vochysia ferruginea show a unique tendency, whereas Enterololium cyclocarpum and Samanea saman showed two tendencies. Drying rate in relation to time showed that it is possible to define the various stages during drying and the inflexion points in time where a change in the drying rate occurs. Two types of tendencies are shown in the drying rate vs. time relation in C. alliodora, E. cyclocarpum, and S. saman, whereas three tendencies appear in D. panamensis, H. alchorneoides, V. ferruginea. C. alliodora, E. cyclocarpum, and S. saman presented only one inflexion in the drying rate, which can be maintained at an average of 24.5, 11.64, and 7.83%/day, respectively, for those species. On the other hand, D. panamensis, H. alchorneoides, and V. ferruginea showed two inflexions. [ABSTRACT FROM AUTHOR]

When wooden supports of panel paintings have been severely altered or damaged and the original cross beams are missing, new cross beams or other types of auxiliary supports are connected to the panel's back-face in order to achieve desired effects including panel strengthening and control of deformations. Some conservation laboratories use small wooden blocks, each glued on the back face of the panel and holding freely the head of a screw connected (often by means of springs) to the auxiliary support; such blocks being called in Italian 'piedini' or 'bottoni', the English term 'buttons' is proposed here. This paper reports research aiming to characterize the mechanical behavior of three types of 'buttons' having different geometries and made of various wood types (oak, walnut, lime, beech, and a medium density fiberboard). Short-term mechanical tests (∼1 minute duration) were performed with a universal testing machine by axially pulling out the 4 mm diameter steel screw from the button, glued onto a dummy board. Load and deformation were recorded, and the load-deformation curves were analyzed. The results show that the deformability and the load-carrying capacity of the buttons were influenced primarily by the manufacturing geometry and secondarily by the wood density. [ABSTRACT FROM AUTHOR]