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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]

South Africa is a water scarce country with minimal natural forests. Plantation forest species such as the Mexican tropical hard pine, Pinus patula Schiede & Deppe ex Schltdl. & Cham., was introduced into the country to satisfy local fibre demand. Today, the majority of pine plantations in South Africa are found in the Mpumalanga province. The province has diverse growing conditions in relation to climate and soil properties. Sample plots were established in even-aged P. patula plantations and stratified according to soil parent material and altitude. Growing conditions of each sample plot were characterised according to climate and soil properties. A total of 540 sample trees were measured for height, diameter, density, and latewood content. The sample trees were harvested to produce 2690 logs. The logs were milled, and the resultant lumber was graded according to density, dynamic modulus of elasticity, and modulus of rupture. Annual maximum temperature had the most significant impact on tree growth, while rainfall correlated with wood density and latewood content of standing trees. However, annual maximum temperature and tree height had a negative relationship with the recovered lumber properties and dimensional stability. Spring rainfall appeared to be the most important factor influencing lumber twist and this was possibly due to the associated larger juvenile core present in the trees. [ABSTRACT FROM AUTHOR]

The effects of periodic hot-press drying on drying behavior and mechanical damage to Chinese fir lumber were investigated by taking the heating platens' temperature (TP) and compression ratio (Rc) as experimental factors. The temperature and pressure inside lumber were analyzed during drying process. The results were as follows. The drying rate of lumber was significantly increased with increasing TP and Rc. Scanning electron microscope (SEM) micrographs showed that bordered pit membranes, cross-field pits, middle lamella between adjacent cells, and tracheid walls were damaged after drying, and the damage became more severe with higher TP and Rc. Detachments between ray parenchyma cells and tracheids were observed at 170 °C. Nitrogen-adsorption measurement results demonstrated that more cell wall pores in the 2.5~6.2 nm pore diameter range were generated at higher TP, resulting in an enlarged specific surface area and pore volume of cell walls. These structural changes contributed to accelerating moisture migration and decreasing the drying time. Furthermore, fluctuating pressure inside lumber was the main driving force leading to moisture migration and cell tissue damage in lumber during drying. The influence of TP on internal temperature (TM) and pressure (PM) was greater than Rc. With the increase in TP from 130 to 170 °C at the Rc of 10%, the maximum TM and PM were increased by 30.90% and 39.84%, respectively. However, TP should not be too high to prevent the formation of macro-cracks caused by high pressure, which may significantly affect wood's mechanical properties. These results provide theoretical support for periodic hot-press drying processes' improvement and high-value utilization of Chinese fir. [ABSTRACT FROM AUTHOR]

Timber architectures have arisen as sustainable solutions for high-rise and long-span buildings, assisting in implementing a circular economy. The creep strain dissipation of laminated veneer lumber (LVL) was investigated in this work to understand the inherent creep behaviors of LVL derived from natural wood. The results demonstrated a significant loading regime dependency of the creep behaviors of LVL. Coupled creep strain dissipation that transits/is parallel to the wood–adhesive interface was proven in the creep deformation of flat-wise and edge-wise bent LVL. In contrast, the creep strain dissipated considerably along the wood–adhesive interface when the LVL was subjected to axial compression creep. Further investigation into the morphologies of LVL after creep revealed that direct contact between the loading plane and wood–adhesive interface could be a plausible trigger for the accelerated deformation and the resultant plastic deformation of the LVL after creep. We believe that this work provides essential insights into the creep strain dissipation of LVL. It is thus beneficial for improving creep resistance and assisting in the long-term safe application of LVL-based engineered wood products in timber architectures. [ABSTRACT FROM AUTHOR]

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This study aims to assess the effect of notches and holes on the structural performance of laminated veneer lumber (LVL) joists using experimental and numerical methods. A total of 40 samples were manufactured with three different notch depths and without notch and tested under a three-point bending load. Subsequently, detailed numerical models were developed and validated with experimental results. The effect of a notch, hole, and location on the load-carrying capacity, shear and flexural stress, and flexural stiffness of the LVL joist were evaluated through the validated numerical model. Results showed that the hole and notch significantly affect the structural performance of the LVL joist. Further, the notch or hole in the middle of the bending span induces a higher load-carrying capacity reduction (i.e., more than 50%) than that of from shear span. Further, the larger hole (i.e., size beyond 33% of the joist' depth) located in the shear and bending span reduced the load-carrying capacity by more than 15% and 50%, respectively. A similar reduction was also observed in the flexural and shear stress of the LVL joist. Moreover, this study proposed a response surface-based model to predict the failure load and flexural stiffness of LVL joists with and without holes and notches. [ABSTRACT FROM AUTHOR]

Thin Spruce-Pine-Fir (SPF) lumber (96x42x2440mm) was conventionally dried aiming to reduce the drying time without affecting lumber quality. The following approaches were tested: (1) lower dry-bulb temperature during the earlier stages of drying combined with higher wet-bulb depression (2) higher wet-bulb depression throughout the entire drying process (3) incremental increases in dry-bulb temperature during the final stages of the drying process. The drying time was reduced from 48 to 38 hours without affecting lumber quality or the standard deviation of final moisture content. In addition to reduced drying times, it is estimated that up to 20% energy reduction and emitted greenhouse gases (reduced CO2 emissions generated by the drying times), can be achieved. [ABSTRACT FROM AUTHOR]

The yield of Eucalyptus regnans logs for lumber production was evaluated. Crack width and length at each log end were measured. Two log-cutting plans were used to obtain sawn lumber. The first plan (PA) considered logs with diameters varying from 28 to 40 cm, and in the second plan (PB), the log diameters ranged from 42 to 56 cm (PB). Lumber yield was determined using two log volume methods: the Japanese Agricultural Standards (JAS) and Smalian's equation. The deformations of E. regnans lumber were measured. The Australian and Chilean standards were used to classify sawn lumber. The results showed that logs had radial cracks at both log ends. Cracks were classified into two groups, considering the crack length. Regarding the lumber deformations, most boards exhibited level B bows and crooks in both cutting plans. Levels A and B twists were prevalent in PA, whereas in PB, level A significantly outnumbered level B. The lumber yield of E. regnans in PB was higher than in PA. The lumber yield determined by Smalian's equation was higher than that determined by the JAS method. This research provides insight into the characterization of E. regnans for lumber production, highlighting its relevance in the forestry industry. [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 paper proposes a modern approach to the automated design of three-dimensional models of wood drying chambers and the study of their operation parameters using the SolidWorks Simulation tool, which makes it possible to create various information models using computer tools. Therefore, in this paper, a three-dimensional model of a wood drying chamber was developed and presented, which includes its main components: walls, ceilings, door, stacks of lumber to be dried, a fresh air supply system, a system for its circulation through fans and heating through heaters. For the automated design of three-dimensional models of all these components, the corresponding algorithms were also developed and programmatically implemented using a specialized SolidWorks application programming interface. At the same time, the developed software application takes into account the parameters entered by the user, including the size, quantity, and type of lumber to be dried. In addition, several thermal calculations were performed across the stack, including with different air velocities. This allows us to analyze the effect of this speed on the distribution of heat transfer across the stack. In general, the obtained results are automatically displayed in one of the windows of the software application. This approach makes it possible to obtain results in the background of SolidWorks with minimal user intervention. Despite the fact that such studies are carried out in SolidWorks Simulation, the graphical results, including the temperature distribution across the stack, are fully automated without user intervention. The software application also makes it possible to automatically change the geometry of a three-dimensional model of a wood drying chamber or stacks within specified limits. In turn, the use of the developed software application in combination with SolidWorks Simulation can effectively speed up the process of creating three-dimensional models of wood drying chambers and studying their operation parameters. In general, this work reflects the trend towards digital transformation in industry, opening up new opportunities for woodworking enterprises and contributing to their market competitiveness and production efficiency.

Spiral grains are one of the most important tree growth defects that can remarkably affect the shape stability of lumber. This growth defect is observed by an oblique arrangement of axially oriented cell elements in the wood. This research focused on identifying and measuring selected shape changes caused by the spiral grains in the log. Hornbeam logs with spiral grain and with no spiral grain aged 60 and 52 years were selected to detect shape changes. Following the research and the norms of STN EN 1309-3 (49 1013), DIN (4074-5), and ASTM D245, it can be stated that spiral grain is an essential factor affecting the shape stability of hornbeam lumber. In the case of lumber with spiral grain, the spiral grain increased by up to 8° within three months. The warp of both types (bow, crook) increased exponentially throughout the study, peaking between the third and fourth week with an increase in warp bow of 26 mm and 17 mm in warp crook.

Trembling aspen (Populus tremuloides) is one of the major species within Populus, a predominant genus of hardwoods in North America. However, its utilization has been limited to pulp and paper or wood-based composite boards. This study aimed at evaluating the major physical and mechanical properties of trembling aspen lumber, with an ultimate objective of using this species to produce engineered wood products (EWPs). The testing materials consisted of 2 × 4 (38 mm × 89 mm) trembling aspen lumber pieces in lengths of 8, 10, and 12 feet (2.44, 3.05, and 3.66 m) with two visual grades, select structural (SS) and No. 2. Machine Stress-Rated (MSR), and longitudinal stress wave (LSW), edgewise third-point bending (EWB), and axial tension tests were conducted on the lumber. It was found that, (1) by increasing the maximum knot size by a half-inch from one-quarter inch, the minimum modulus of elasticity (MOE) measured using the MSR, the mean, and the fifth-percentile ultimate tensile strength (UTS) decreased by about 8.8%, 20.1%, and 29.8%, respectively. (2) Approximately 44% of the trembling aspen lumber met the 1450f-1.3E grade for MSR lumber, and 62% qualified for the 1200f-1.2E grade. (3) There was a great potential for manufacturing cross-laminated timber (CLT) of grade E3, with a rejection rate of about 29%. (4) The mean UTS and MOE values of the SS-grade trembling aspen lumber were 22.88 MPa and 9519 MPa, respectively, being 25.5% and 11.3% lower than that of Spruce–Pine–Fir (S-P-F) lumber. The fifth-percentile UTS and MOE values were 11.57 MPa and 7404 MPa, respectively, marking a decrease of 13.3% and 1.5% compared to the S-P-F lumber. (5) The oven-dried specific gravity (SG) of the trembling aspen wood was 0.40, which was about 3.5% larger than the value provided in the Wood Handbook.

The mechanical properties of materials such as lumber (L), glued laminated timber (GLT), cross-laminated timber (CLT), and Ply-lam CLT (P), which are laminated in cross layers, were compared. As a result, the modulus of elasticity (MOE) was 9.7 to 10.3 GPa, showing no significant difference between the materials. Modulus of rupture (MOR) of L and GLT showed higher strength than that of CLT and P. MOR of CLT and P was at the same level, and there was no difference in strength according to the plywood and lumber arranged alternately. Alternatively, there was a difference in the coefficient of variation of the materials, and CLT and P was 20.2% and 11.8%, respectively; therefore, uniform properties can be secured when using plywood. The compression strength showed the highest compression strength in the order of GLT, L, P, and CLT. P was failure by buckling+delamination, but other materials showed failure by only buckling. The adhesion of P passed the glulam standard (7.0 MPa), and the delamination ratio was very low at 0.41%. It can be used together with CLT. This study is expected to be used as basic data for establishing quality standards.

This study presents a testing campaign aimed at evaluating the strength and stiffness properties of laminated veneer lumber (LVL) specimens. LVL is an engineered wood product composed of thin glued wood veneers whose use in construction for structural applications has increased due to its sustainability and enhanced mechanical performance. Despite LVL's growing popularity, there is a lack of comprehensive information regarding stress–strain responses, failure modes, and the full set of strength and stiffness properties. These are particularly essential when LVL is employed in pure timber structures or composite systems such as steel–timber or timber–concrete load-bearing elements. This research aims to bridge this knowledge gap, focusing on crossbanded LVL panels, known as LVL-C, crafted from Scandinavian spruce wood, which is an LVL product with 20% of crossbanded veneers. The study explores LVL-C mechanical behavior in three primary orthogonal directions: longitudinal, tangential, and radial. A series of mechanical tests, including compression, tension, shear, and bending, was conducted to provide a thorough assessment of the material's performance. In compression tests, different behaviors were observed in the three directions, with the longitudinal direction exhibiting the highest stiffness and strength. Tensile tests revealed unique stress–strain responses in each direction, with gradual tension failures. Shear tests showcased varying shear stress–strain patterns and failure modes, while bending tests exhibited significant strength and stiffness values in flatwise bending parallel to the grain and flatwise bending perpendicular to the grain. This paper summarizes the comprehensive testing results and discusses the obtained strength and stiffness properties of LVL-C panels, providing valuable insights into their mechanical behavior for engineering applications. [ABSTRACT FROM AUTHOR]

This study provides novel insights into the policy effects of timber legality verification methods, specifically Due-diligence (under the European Union Timber Regulation (EUTR)) and Due-care (under the Lacey Act), on coniferous and non-coniferous lumber trade, highlighting their significance in the context of global lumber trade. Timber legality verification plays a pivotal role in the global timber trade. We comprehensively assess the impact of verification methods on coniferous and non-coniferous lumber trade, utilizing two decades of trade data (1997–2017) across approximately 160 countries. We employ the difference-in-differences method based on the gravity model of international trade, utilizing robust export–import data and demographic profiles. Our findings demonstrate that the effect of EUTR on coniferous lumber imports ranged between −0.32% and −0.05%, and that on non-coniferous lumber imports ranged between −0.44% and −0.05%, whereas the effect of the Lacey Act on coniferous lumber imports ranged between −0.93% and −0.09%. Non-coniferous lumber imports remained unaffected. The Voluntary Partnership Agreement (VPA) led to decreased exports to the EU and US. Our findings hold two key implications. First, Due-diligence exhibits more consistent policy effects than Due-care. Second, supporting VPA-participating countries is crucial for facilitating timber trade. These insights inform timber trade policies and sustainable practices. [ABSTRACT FROM AUTHOR]

The creep behavior of fiber-reinforced polymer (FRP) reinforced larch laminar timber was studied with respect to temperature and humidity fluctuations. There was a control group of larch laminated with two smalldiameter timbers with FRP (carbon FRP (CFRP), glass FRP (GFRP)) produced; the laminated lumber had the same cross-sectional area as the two laminated lumber specimens with reinforced tensile parts. A creep test with fluctuating temperature and humidity was conducted by applying a load of 25% of the bending strength of the control specimen. A total of 8 specimens, 2 for each type, were measured for creep deformation at 9:00 am and 6:00 pm daily for approximately 14,000 h. Temperature and humidity fluctuations were measured every hour. The equilibrium moisture content and humidity of the creep test space exhibited a proportional relationship, and the moisture content of each specimen did not show a noticeable correlation with humidity and equilibrium moisture content. The average relative creep was measured as approximately 0.67 for the control, 0.4 for Glulam, and 0.43 for both the CFRP- and GFRP-reinforced specimens. Thus, the creep deformation of all the reinforced pieces was confirmed to be lower than that of the control specimen. [ABSTRACT FROM AUTHOR]

Parallel-strand lumber was manufactured with bamboo (Phyllostachys bambusodies). A polyol compound was added to modify the adhesive (pMDI). Bamboo culms were used to manufacture strands 3 mm thick, 19 mm wide, and 65 cm long. Adhesive was applied to the strands at 200 g/m2 with pressing at 110 °C, 15 kg/cm², and 30 min. Panels were made with width 600 mm, length 600 mm, and thickness 20 mm. Some physical properties (oven-dry density, air-dry density, moisture content, thickness swelling, and water absorption percentage) and mechanical properties (bending resistance, modulus of elasticity, impact resistance, screwholding capacity in tangential, radial, and transverse directions) of parallelstrand lumber for both adhesive types were determined. Both resin types improved some physical and mechanical properties of parallel-strand lumber. Additionally, the modulus of rupture and flexural modulus of elasticity of the test specimens using pMDI+5%MP adhesive were higher than those of the test specimens using pMDI. The average screw-holding capacity values of the test specimens were affected by the fiber aspect of the specimens rather than the adhesive type. Parallel-strand lumber produced from both pMDI and pMDI+5%MP adhesives can be used in structural applications, especially in places exposed to the disturbing effects of weather. [ABSTRACT FROM AUTHOR]

The dynamic loadings can be more harmful than static ones for the human lumbar spine health. Consequently, the prediction of the spine behavior under dynamic and vibration loads is vital and can be achieved by creating a precise finite element model in which the dynamic mechanical properties of the components need to be estimated. For this purpose, noninvasive experimental modal analysis can be applied to evaluate the dynamic mechanical properties of the spine in the numerical simulation by supplying the structural dynamic characteristics (natural frequencies, mode shapes, and damping ratio) of the system. Since the most adequate model for the human lumbar segment is a sheep model, in this paper, a 3D finite element model of a fresh spinal lumber segment of a sheep is generated based on the poroelasticity theory via Abaqus and is updated utilizing particle swarm optimization (PSO) algorithm and experimental modal analysis. In this regard, the frequency response function (FRF) of the specimen is obtained by performing the experimental modal test and the modal parameters are derived by using the rational fraction polynomial method. Afterward, the sensitivity analysis is carried out to determine the appropriate design variables. Finally, the PSO algorithm using experimental data is employed to update the design variables, including the elastic material properties and the structural damping factors of the specimen components, and the stiffness and damping coefficient of the suspension system. According to the results, the error percentage between the numerical FRF and the experimental one decreases remarkably after model updating indicating the high efficiency of the methods used. [ABSTRACT FROM AUTHOR]

Objective: To determine the diagnostic accuracy of FLAIR MRI in identifying acute Subarachnoid Hemorrhage (SAH) using Lumber puncture (LP) as a gold standard. Materials and Methods: This was a validation study conducted from 3rd September 2020 to 3rd February 2021 at the Department of Radiology, Khyber Teaching Hospital, Peshawar. The sample size was 266. A non-probability consecutive sampling technique was used. All alert patients aged 20-70 years with sudden acute headache, other signs of SAH (nausea, vomiting, blurring of vision, sensitivity to light, and neck stiffness), and GCS >13 were included in this study. SAH on FLAIR-MRI was determined based on high signals in the subarachnoid space on FLAIR. Diagnostic accuracy was calculated regarding sensitivity, specificity, and positive and negative predictive values. SPSS version 22 was used to perform statistical analysis of the data. Results: Mean age ranged from 20 to 70 years (46.3 + 14.1 years), with 58.6% male, and 41.4% female subjects. On FLAIRMRI, SAH was observed in 65.4% of patients while SAH was recorded in 57.5% of patients on follow-up LP. Sensitivity of FLAIR-MRI was found to be 91.5% and specificity 69.9%. FLAIR-MRI had 80.5% positive predictive value and 85.8% negative predictive value. Conclusion: FLAIR-MRI is effective in accurately identifying SAH with high sensitivity and fair specificity. As such, it is a useful radiological tool for diagnosis of SAH in adults and further studies are recommended to confirm its usefulness. [ABSTRACT FROM AUTHOR]

Due to the high growth rates of the forests planted in Brazil and the variations of the mechanical properties within a tree, this study aimed to evaluate the strength (MOR) and stiffness (MOE) in static bending according to the juvenile and adult wood, and the grown-rings inclination at the transversal area of clean specimens of Pinus taeda. Subsequently, the woods were classified in its structural gradings. Pinus taeda logs with 30 years old had the growth rings delimited at every six years on the transversal area. The juvenile wood was represented by the zone of 0 to 6 years of growth (marked with red), and 6.1-12 years (blue). The zone of 12.1-18 (orange) was considered as transition wood and from 18.1-24 (green) and 24.1-30 years (yellow), adult wood. After the sawing, 25 boards were selected to the sawing of the specimens (n = 104) for the static bending test. Growthring inclination was measured as a function of the direction of the load applied at the bending test. Statistical tests were performed in a factorial scheme with the MOR and MOE to static bending. Factors were independent (mechanical properties and growth-rings inclination). The 0-6-year-old wood was not indicated for structural use. Woods between 12-30 years old showed a minimum compatible result to be classified for structural use. The inclination did not influence at the modulus of elasticity and strength at bending. [ABSTRACT FROM AUTHOR]

The article considers the design of mobile installations for longitudinal s awing of timber. The patent search method was used. The idea is based on research well known in the field and does not contradict their conclusions. The aim of the work is to find options for reducing physical effort during stacking and loading lumber during longitudinal sawing in a cutting area in the absence of specialized equipment at loading sites and consumer warehouses. The authors describe in detail a new method of work and the design of a mobile installation for longitudinal sawing of timber in a cutting area, which makes it possible to achieve the possibility of producing boards in the form of incompletely sawn logs. It becomes possible to carry out loading and unloading operations using a manipulator equipped with a standard grab without the use of manual labor or specialized machines and mechanisms. The proposed method of longitudinal sawing consists in the fact that on the end parts of the timber there are triangular unsawn wood. The subsequent separation of the sawn timber into boards is carried out at the consumer's warehouse by either transverse sawing and removal of unsawn end parts, or longitudinal sawing of the remaining unsawn cuts. The method of longitudinal sawing of timber can be used in small-scale logging enterprises located near product consumers. The proposed work option is especially relevant in the absence of our own warehouse with stationary equipment for longitudinal sawing of timber, loading and unloading timber trucks. [ABSTRACT FROM AUTHOR]

The inclusion of rubber in concrete has been suggested and used in recent research. However, the reason for the inclusion of rubber into concrete is typically the need to offset the carbon footprint of concrete and other environmental concerns. The research presented here indicates that the inclusion of rubber into concrete allows for the concrete to accept fasteners and withstand withdrawal, or pullout, of the fasteners, similar to the function of wood. We refer to this as making the concrete "nailable", in that the concrete can be nailed together either by hand or with tools designed to be used with wood. While other methods have been used to make concrete nailable, this method is novel as no known research exists indicating that there exists a rubber concrete mix that provides similar withdrawal strength as wood. Testing indicates that the concrete can be produced at a low cost due to the inclusion of the low-cost rubber infill with reinforcement wire. The result is a reinforced concrete with an allowable load that is 13% greater than in spruce and a withdrawal force up to 25% greater than the maximum in spruce. The intended function of this material is replacement of treated lumber. The proposed rubber concrete, which is a reinforced concrete, is anticipated to have a service life of 50–100 years, while treated lumber decks in the Southeastern United States have been surveyed to have an average life of only 10 years due to environmental degradation. This leads us to conclude that if a deck were to be constructed of this nailable rubber concrete, it would last approximately five times longer in a temperate environment, such as the Southeastern United States. This improvement can be provided at a relatively low cost while providing an alternative that both prevents the use of arsenic- and copper-containing compounds used in treated lumber and provides an additional recycling method for tires. [ABSTRACT FROM AUTHOR]

Lumber is one of the most essential forest products in the United States. During the first year of the COVID-19 pandemic, lumber prices almost quadrupled, and fluctuations reached record levels. Although market experts have pointed to various drivers of such high price volatility, no firm conclusions have been drawn yet. Using the generalized autoregressive conditional heteroskedasticity-mixed data sampling (GARCH-MIDAS) framework, this study assesses the potential drivers of lumber price volatility, with predictors including the Google Trends Web Search Index, housing starts, US lumber production quantity, and VIX index, representing public attention, housing demand, lumber supply, and macroeconomic concerns, respectively. We have found that housing demand is the key driver of lumber price volatility, followed by public attention. It is worth noting that US lumber supply and macroeconomic concerns have played a modest role in explaining lumber price volatility. Also, forecasting lumber price by using the housing demand variable substantially outperforms others. Market participants, including lumber mills, wholesalers, and home builders can get valuable information from the housing market to manage lumber price risk. [ABSTRACT FROM AUTHOR]

Turkey oak lumber is difficult to dry, being prone to cracks even at low temperatures. The main objective of the research was to test different drying conditions in order to establish whether air-drying or kiln-drying from a green state was more suitable; if the lumber width had an influence on the drying quality; if prior steaming had a positive effect upon the kiln-drying time and quality; if end cracks could be avoided by protecting the board ends; and what the most appropriate kiln-drying conditions were, with conventional drying. The research results recommend kiln-drying as a better alternative than air-drying in terms of both time and quality, but very mild conditions must be applied. Wide lumber parts cracked both when air-dried and when kiln-dried. All defect-free lumber parts dried accurately, with no deterioration. Steaming had a positive effect upon the drying quality; no steamed part cracked. The end protection of the boards was efficient only in the case of kiln-drying. [ABSTRACT FROM AUTHOR]

In recent years, much attention has been focused on carbon accounting for harvested wood products in national greenhouse gas inventories. The methods used for national accounting, however, are not suited to corporate or value chain accounting. This is largely due to the practical difficulties that companies face in assembling the historical production data and other information required by national accounting methods. In addition, national accounting methods produce results that are heavily influenced by historical data and past practices. As a result, these methods provide little insight into opportunities for improvement. In this paper, options are considered for corporate and value chain accounting of carbon in forest products in use. One method is identified that avoids many of the difficulties associated with national accounting methods. The method estimates the amount of carbon in products expected to remain in use for at least 100 years and, therefore, the method is called the 100-year method. A review of forest product time-in-use distributions being used in several countries to develop national carbon inventories reveals that many of them were not designed to produce realistic estimates of the amount of product remaining in use for 100 years. U.S. housing data are used to demonstrate, however, that the time-in-use information used to develop the U.S. national inventory can be used in the 100-year method without over estimating 100-year carbon sequestration in U.S. housing. [ABSTRACT FROM AUTHOR]

In this study, the tensile mechanical properties of bolted laminated bamboo lumber (LBL) loaded parallel to the grain were investigated under the influence of end distance and bolt spacing according to ASTM D5652-95. A total of 32 specimens were tested and the bearing capacity was calculated based on the 5% D offset method. The test results showed that: end distance and bolt spacing both regularly affected the initial stiffness and bearing capacity of the specimens, while there was no significant effect on the yield stiffness; with the enlargement of end distance and bolt spacing, the ductility ratio gradually increased and tended to stabilize, and the failure mode shifted from brittle failure to ductile failure, resulting in the recommended minimum size requirements for bolted LBL as follows: 8 times the bolt diameter for the end distance and 7 times the bolt diameter for the bolt spacing. The bolted connection bearing capacity of different materials as well as that obtained by different calculation methods were compared with the experimental results, allowing the empirical equations for predicting the yield load of bolted LBL to be put forward. [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]

Climate change is one of the main factors influencing the research of environmentally friendly materials. This is why the use of engineering fibers as a reinforcement technique in wood, in order to increase its mechanical properties, has recently been investigated. This research presents the results obtained from the use of carbon and basalt fiber fabrics as a reinforcement for microlaminated Radiata Pine wood panels at a laboratory scale using the adhesives epoxy resin and polyvinyl acetate. Tests were carried out in comparison to the control boards, relating the physical properties obtained in terms of thickness swelling by 48 h-water immersion with a decrease of 19% for the polyvinyl acetate and carbon fiber matrix reinforcement, about the mechanical properties evaluated, a better performance was obtained for the epoxy resin and carbon fiber matrix reinforcement and in terms of flexural stiffness and strength (in flatwise), tensile strength and Janka hardness, with an increment of 31%, 38%, 56% and 41%, respectively. [ABSTRACT FROM AUTHOR]

This contribution presents the results of analytical and numerical investigations of the ultimate bending resistance of simply supported steel‐timber composite beams with uniformly distributed load, they consist of three main components: (i) the laminated veneer lumber (LVL) slab, (ii) the downstand steel beam (IPE‐profile) connected by means of (iii) demountable shear connectors, which allow for deconstruction and circular reuse of the steel beam as well as the timber slab element. The mechanical properties of the cross‐banded LVL as well as the load‐slip curves of demountable shear connectors, which have been obtained experimentally, were implemented in both the analytical and numerical models. In this paper both solutions have been compared, first the ultimate bending resistance was calculated analytically through a strain‐controlled approach with various degrees of shear connection. Then, numerical simulations were conducted in the finite element software ABAQUS to determine the ultimate bending capacity and the load‐deformation behaviour. Finally, the results of both approaches are presented and compared. [ABSTRACT FROM AUTHOR]

This paper experimentally investigates the influence of the strain rate experienced during earthquake and progressive collapse events on mechanical properties affecting the design of softwood laminated veneer lumber timber connections. The parallel and perpendicular to grain embedment stiffness and strength, tension strength perpendicular to grain, and Mode I and II fracture energies were examined under four levels of strain rates. Results showed that the embedment stiffness and strength increased by up to 35% from the quasi-static to dynamic strain rates, whereas the embedment ductility decreased by up to 17%. The fracture energies and tension strength perpendicular to grain were found to be mostly insensitive to the investigated range of strain rates. Furthermore, the influence of the strain rate on the behavior of timber connections is analyzed and discussed by (1) using the experimental data in the European standard design equations for single and double shear connections; and (2) quasi-statically and dynamically testing one connection type with two different fastener spacings. Results showed that for the connections investigated, the dynamic strength can be up to 30% higher than the quasi-static one, however, the dynamic ductility of the connections can be reduced substantially by up to 32.5%. [ABSTRACT FROM AUTHOR]

Acoustics is a field with significant application in wood science and technology for the classification and grading, through non-destructive tests, of a large variety of products from standing trees to building structural elements and musical instruments. In this review article the following aspects are treated: (1) The theoretical background related to acoustical characterization of wood as an orthotropic material. We refer to the wave propagation in anisotropic media, to the wood anatomic structure and propagation phenomena, to the velocity of ultrasonic waves and the elastic constants of an orthotropic solid. The acoustic methods for the determination of the elastic constants of wood range from the low frequency domain to the ultrasonic domain using direct contact techniques or ultrasonic spectroscopy. (2) The acoustic and ultrasonic methods for quality assessment of trees, logs, lumber and structural timber products. Scattering-based techniques and ultrasonic tomography are used for quality assessment of standing trees and green logs. The methods are based on scanning stress waves using dry-point-contact ultrasound or air-coupled ultrasound and are discussed for quality assessment of structural composite timber products and for delamination detection in wood-based composite boards. (3) The high-power ultrasound as a field with important potential for industrial applications such as wood drying and other applications. (4) The methods for the characterization of acoustical properties of the wood species used for musical instrument manufacturing, wood anisotropy, the quality of wood for musical instruments and the factors of influence related to the environmental conditions, the natural aging of wood and the effects of long-term loading by static or dynamic regimes on wood properties. Today, the acoustics of wood is a branch of wood science with huge applications in industry. [ABSTRACT FROM AUTHOR]