Wood Loads Research Articles

Loading Round Wood in Forestry Trucks and Forestry Platforms: A Case Study for Romania

Wood, as the main product of the forest, must be brought from the forest to various beneficiaries by various vehicles. The choice of a particular type of vehicle should consider the characteristics of the area from which the wood is loaded, the wood-storage yard, and the availability of a certain model. Besides this, the assortments and quantities of wood to be transported influence, to a large extent, the type of vehicle, which has consequences for transport efficiency and productivity. The aim of the paper was to evaluate the wood-loading process in various types of transport vehicles in terms of time consumption for each working phase and the factors that can affect productivity. The research was carried out in four counties of Romania and addressed the loading of wood in different forestry trucks and platforms, with or without trailers. Transport distances were documented in Brasov County based on 200 transport documents. To evaluate the transport distances in the case of wood intended for contractors, field measurements were carried out in three different are as managed by the private Lignum Forest District (Bacău County). The study of the loading process and productivity estimation at loading was carried out in three locations, namely Bacău County, Sibiu County, and Caraș-Sever in County. To observe whether there are differences in the loading of tree lengths from the harvesting area in various types of vehicles (forestry trucks—ATF—and forestry platforms—APF), research was carried out in Caraș-Sever in County. After processing the data, it was found that in the forests managed by the state and in the forests owned by the local public administrations, the fuelwood reaches mainly locals, and the working wood reaches some wood processing companies. For forestry trucks (ATFs), the loading time was somewhat constant, while for forestry platforms (APF), it varied, with differences observed from the first to the last loading. Following the evaluation of the work-element phases specific to the operation of loading round wood into vehicles, it was found that, sometimes, significant importance is given to the working elements as phases of preparation of the wooden material that can be carried out before the loading process, in order to load it. To eliminate delays in the loading process, it is recommended that logs are prepared before loading, which will increase productivity and it will decrease the risk of accidents for workers who perform these tasks during the loading process.

Design of Pedal Bicycle Prototype using the PID Controller as an Alternative Energy Generator

In recent years, electricity consumption in Indonesia rose to 1.109 kWh, as the Ministry of Energy and Mineral Resources reported. An alternate method for generating electrical energy is harvesting the energy produced via exercising on a stationary bike. By employing Arduino Mega 2560pro-powered torque control using the PID (Proportional – Integral – Derivative) technique, we can effectively save the generator's power in the battery and modify the paddle load to match the user's desired settings. The design incorporates a repurposed bicycle that has been rebuilt, along with the addition of a transmission gear, a controller box housing a control circuit, a relay, and an inverter. Additionally, it is equipped with a display and buttons. This system can generate a paddle load ranging from 1 to 17 in normal mode and 1 to 10 in PID mode. The system has a maximum current output of 3.2A and a battery capacity of 24VDC. This DC voltage is then transformed into a 220 VA AC voltage suitable for residential electrical use using an inverter. The PID controller will regulate the current flowing into the battery, ensuring it remains steady even with a consistent wood load. PID control can reach a set point at the settling time, 7 s, with an overshoot and a steady-state error of 0%. Every motor achieved the Pulse Width Modulation (PWM) value set to the ideal current. As the RPM increases, the PWM decreases until it reaches the preset set point with a constant current value.

Impact loading of glued laminated timber beams without finger-joints

Progressive collapse can be triggered by impact loading from vehicles or other objects and propagated by impact loading from falling debris. Therefore, the correct modeling of impact loading is necessary to assess the resistance of a structure against progressive collapse. As the number of timber buildings increases, the importance of adequate considerations of impact loading is growing. Previous research on impact loading of wood or timber was carried out on small clearwood specimens or on single boards. However, modern timber buildings use advanced wood-based composites, such as glued laminated timber and laminated veneer lumber. The characteristics of these materials are widely different from clearwood and single boards. In this paper, energy-based equations are derived for the peak impact force and the dynamic strength increase factor. These are quantified by pendulum impact hammer tests on 95 full-size glued laminated timber beams. The results are applied in a calculation example to demonstrate their potential use in practice.

Snow Avalanches as a Driver of Large Wood Dynamics in Mountain Streams

AbstractSnow avalanches are thought to influence large wood dynamics within mountain streams, but studies that explicitly quantify their impact are minimal. In three headwater catchments of the Frying Pan River, Colorado, USA, we found that wood loads in stream reaches intersected by avalanche pathways ranged from 220 to 8,500 m3/ha and were significantly greater than in non‐avalanched reaches. Inter‐catchment differences in the number of avalanche occurrences were not reflected in control reach wood loads, suggesting that elevated loads may be restricted to the general vicinity of the avalanche pathway. However, the sizable wood volumes in avalanche reaches generated notable geomorphic impacts, indicating that avalanches can create hotspots of in‐stream geomorphic complexity and influence the overall habitat mosaic of the stream ecosystem. Loads in avalanche reaches were moreover significantly greater than literature values for similar streams and recruitment processes, emphasizing the importance of snow avalanches as a wood recruitment mechanism.

Tracing past extreme floods on an alluvial fan using geophysical surveying

SummarySedimentary units in alluvial fans may record gradual transport and deposition during multiple floods or sediment‐laden flows or, conversely, during few catastrophic events. While outcrops are a valuable source of direct information to constrain past geomorphic and hydrologic processes, such exposures are scarce, especially along aggrading rivers or those that have been subject to recent catastrophic sedimentation. In this context, near‐surface geophysical techniques can constrain the dimensions, internal architecture, composition, and petrophysical properties of different sedimentary units. We consider the Grimmbach alluvial fan in the cuesta landscape of southwestern Germany, which was heavily impacted by sediment and wood loads during a flash flood in 2016; published radiocarbon dates indicate that at least three floods similar to the one in 2016 may have occurred since the 17th century. To test whether and to which detail near‐surface geophysics might reveal the sedimentary legacy of these floods, we survey the Grimmbach alluvial fan using detailed topographic data and geophysical imaging based on electromagnetic induction, electrical resistivity tomography (ERT), and ground‐penetrating radar. Our geophysical results indicate former channel courses and two coarse bar deposits up to 3 m below the surface, which are comparable with the more extensive bar deposits of the 2016 flood. From the ERT models, we interpret coarse, up to 5 m thick, gravel lag overlying bedrock at a maximum depth of 10 m. Our geophysical results also highlight patches of finer materials derived from gradual sedimentation and soil development. Overall, our results show that the Grimmbach alluvial fan may have formed and reshaped during catastrophic flows, which likely caused channel avulsions. Our findings point to the need to reconsider flash flood and debris‐flow hazards in similar headwaters and fans of this seemingly quiescent cuesta landscape in southern Germany.

Effect of thermal modification on the ballistic performance of coastal western hemlock Cross-laminated Timber (CLT)

To test and understand the potential for integration of thermally modified coastal western hemlock CLT systems in military applications, 109 ballistic experiments were conducted at the United States Army Engineer Research Development Center's Fragmentation Simulation Facility. For a range of CLT thicknesses, the depth of penetration and residual velocities were recorded for different striking velocities utilizing a 0.50 caliber steel sphere projectile. This information was used to compare and add to the existing ballistics data for CLT, investigate the effects of thermal modification on high strain rate loading of wood, assess physics-based empirical design equations used by the Unified Facilities Criteria, and evaluate energy absorbing behavior at a range of thicknesses and striking velocities.The experimental results showed that thermal modification does not significantly alter the full and partial penetration performance of coastal western hemlock CLT. However, the mechanism of fracture along the path of the projectile differed, which indicates that the model parameters used in the UFC design equation (density, hardness, and projectile properties) may not fully encompass the ballistic failure mechanisms of CLT.

Enhanced Preservative Performance of Pine Wood through Nano-Xylan Treatment Assisted by High-Temperature Steam and Vacuum Impregnation.

This study used environmentally friendly nano-xylan to enhance the drug loading and preservative performance (especially against white-rot fungi) of pine wood (Pinus massoniana Lamb), determine the best pretreatment, nano-xylan modification process, and analyze the antibacterial mechanism of nano-xylan. High-temperature, high-pressure steam pretreatment-assisted vacuum impregnation was applied to enhance the nano-xylan loading. The nano-xylan loading generally increased upon increasing the steam pressure and temperature, heat-treatment time, vacuum degree, and vacuum time. The optimal loading of 14.83% was achieved at a steam pressure and temperature of 0.8 MPa and 170 °C, heat treatment time of 50 min, vacuum degree of 0.08 MPa, and vacuum impregnation time of 50 min. Modification with nano-xylan prohibited the formation of hyphae clusters inside the wood cells. The degradation of integrity and mechanical performance were improved. Compared with the untreated sample, the mass loss rate of the sample treated with 10% nano-xylan decreased from 38 to 22%. The treatment with high-temperature, high-pressure steam significantly enhanced the crystallinity of wood.

Large wood loads in channels and on floodplains after a 500-year flood using UAV imagery in Mark Twain National Forest, Ozark Highlands, Missouri

Anthropogenic climate change has increased the frequency of large floods in rivers draining the Ozark Highlands. This study assesses the effects of a > 500-yr flood in spring 2017 on riparian forests and large wood loads in the North Fork of the White River watershed, Missouri, for six stream reaches with drainage areas from 5 to 124 km2. Standing trees and large wood (LW) were assessed using unmanned aerial vehicle (UAV) imagery and calibrated by field surveys. Scaled flood magnitude (flood stage/bankfull depth) correlated with percent urban and agricultural land above each reach suggesting that land use may have contributed to forest damage. Canopy loss on the valley floor ranged from 7 to 63 % by reach and correlated with mean and cross-sectional stream power (p < 0.01). Standing tree density after the flood ranged from 50 to 243 trees/ha. The density of LW pieces ranged from 25 to 147 trees/ha. Most LW was aligned with stream flow, not in jams, and located on floodplains below riffles or bar heads, along channel bends, or in chutes. Wood loads on the valley floor increased downstream from 12 to 45 m3/ha. Channel loads were < 30 m3/ha while floodplain, terrace, and chute loads were > 30 m3/ha at drainage areas >50 km2. Channel LW loads increased with flood magnitude and in narrow valleys (p < 0.02), but not drainage area. Increased wood storage occurred on floodplains and terraces, but it is not clear if the stored wood will be available for downstream transport by future floods.

Large wood loads in an urban stream: The role of recruitment limitation versus transport dominance

AbstractLarge wood (LW) has important physical and ecological functions in streams. Riparian vegetation is extensively removed during urban expansion, and urban streams may experience enhanced fluvial transport of LW due to flashy hydrology. In this study, LW loads were assessed for three reaches on North Buffalo Creek, an urban stream located in Greensboro, North Carolina, United States. These three reaches have similar hydrology but different riparian vegetation densities. We measured the frequencies and sizes of both in‐channel LW and riparian vegetation across the three reaches. Our results showed that the recently reforested reach had greater LW volume (22.5 m3/km) compared to the unmanaged forested site (16 m3/km) and the site with low riparian vegetation density (4.78 m3/km). The difference in LW frequency among reaches was statistically significant (). However, the difference in the volume of individual pieces was not significantly different across reaches (, indicating that a similar size of wood is recruited across the three sites. Our findings also showed that there is a positive relationship between riparian vegetation frequency and in‐channel LW frequency, which are significantly related as a power function. Spatial lag models (integrating upstream riparian trees) did not show better results compared to a non‐lagged model, suggesting that storage and recruitment were predominantly local and that the LW distribution at our reaches is limited by recruitment rather than dominated by fluvial transport. Our findings suggested that a fully forested watershed is not needed to provide some of the benefits of wood to urban streams.

Monotonic and cyclic load of pine wood under uniaxial compression: experiments and modeling

To analyze the behavior of wood under uniaxial monotonic deformation, we applied an analytical model to separately control of the pre-peak and post-peak branches of the load-displacement curve. Two criteria for the transition of wood into the plastic stage of deformation are considered. To analyze the behavior of wood under cyclic uniaxial deformation, we used the load-displacement curve obtained for monotonic deformation as an envelope. Equations for the plotted of load-displacement curves under cyclic loading with incomplete unloading are proposed. As an experimental and model illustration, the behavior of a pine specimen under cyclic uniaxial compression with incomplete unloading in the range from 8 to 15 kN is considered. Because the highest cyclic load exceeds the load at the point of transition of wood into the plastic stage, the deformation process has already after 54 cycles moved to the downward branch of the load-displacement curve for monotonic deformation. The simulation results are in agreement with experimental and literature data, which suggests the suitability of this method for the study of some wood-based composites.

How does over two decades of active wood reintroduction result in changes to stream channel features and aquatic habitats of a forested river system?

AbstractSince the late 1980s and early 1990s, wood reintroduction has been a commonly assessed stream restoration technique. Many of the efforts have focused on short‐term, localized physical changes and response of salmonids to wood reintroduction. Few have examined how long‐term, spatially extensive increases in wood loadings alter stream channel morphology and the geomorphic processes responsible for these changes. We used before and after photos as well as a wood storage survey with tagged restoration logs in a small, low‐elevation Western Washington watershed to characterize the effects of 23 years of wood additions. In the ~6 km of wood placement we saw an increase in wood loading and channel‐spanning logjams, which contributed to deeper and more frequent pools, a reduction in particle size, increases in sediment storage, reduced stream width, vegetation re‐establishment in the riparian zone, and increased development and maintenance of floodplain channels. The largest geomorphic changes occurred due to restoration wood effectively storing pieces moving downstream. These findings imply that the cumulative habitat restoration actions and associated changes to stream habitat conditions are identifiable through comparison of historical and current photos as well as more quantitative habitat metrics. It also demonstrates that wood placement that simulates the function of large key, stable pieces accelerates habitat recovery within basins subjected to historic logging.

Rediscovering wood‐laden debris flow studies: A perspective from Japan

AbstractDebris flow is one of the dominant processes distributing large wood (LW) within mountainous catchments. However, little has been reviewed on wood‐laden debris flow (WLDF), presumably owing to limited reviewable works. This article, therefore, navigates the international readers through 40 years of WLDF studies, most of which have been published only in Japanese. Firstly, we reviewed the historical development of Japanese WLDF particularly focusing on the 1980s and the 1990s. A series of post‐disaster fieldworks from the July 1982 Nagasaki flood to the July 1990 Kumamoto flood provided 32 catchment‐scale wood budgeting data; empirical relationships among drainage area, dominant tree species, sediment yield, and wood loads associated with single debris flow disasters were illustrated. Secondly, the characteristics of WLDF were summarized based on relevant previous studies on the recruitment, transport, and deposition processes of LW during debris flows. Thirdly, we discussed the connectivity between those Japanese WLDF studies and international LW studies by relating/contrasting their research approaches and spatiotemporal scales. In contrast to global LW research trends, Japanese WLDF studies have almost exclusively regarded LW as hazardous materials (i.e., “driftwood” or “woody debris”) that need to be retained upstream of the inhabited areas. Those practice‐oriented WLDF studies were concentrated on drainage areas of 10−2 to 100 km2, representing 1–6 orders of magnitude smaller spatial scales than those generally covered by existing international LW studies. Strongly motivated by engineering requirements, “dynamic” interactions between debris flows and LW during floods have also been physically presented, mainly based on unique laboratory experiments involving steep flume (&gt; 0.05) and mobile bed conditions. Finally, some future works for WLDF were briefly stated from practical and scientific perspectives. By “rediscovering” those WLDF studies domestically developed in Japanese debris flow channels since the 1980s, a more comprehensive understanding of LW dynamics in the river system may be achieved.

Wood stock in neotropical streams: Quantifying and comparing instream wood among biomes and regions.

Instream wood plays important chemical, physical and ecological functions in aquatic systems, benefiting biota directly and indirectly. However, human activities along river corridors have disrupted wood recruitment and retention, usually leading to reductions in the amount of instream wood. In the tropics, where wood is believed to be more transient, the expansion of agriculture and infrastructure might be reducing instream wood stock even more than in the better studied temperate streams. However, research is needed to augment the small amount of information about wood in different biomes and ecosystems of neotropical streams. Here we present the first extensive assessment of instream wood loads and size distributions in streams of the wet-tropical Amazon and semi-humid-tropical Cerrado (the Brazilian savanna). We also compare neotropical wood stocks with those in temperate streams, first comparing against data from the literature, and then from a comparable dataset from temperate biomes in the USA. Contrary to our expectations, Amazon and Cerrado streams carried similar wood loads, which were lower than the world literature average, but similar to those found in comparable temperate forest and savanna streams in the USA. Our results indicate that the field survey methods and the wood metric adopted are highly important when comparing different datasets. But when properly compared, we found that most of the wood in temperate streams is made-up of a small number of large pieces, whereas wood in neotropical streams is made up of a larger number of small pieces that produce similar total volumes. The character of wood volumes among biomes is linked more to the delivery, transport and decomposition mechanisms than to the total number of pieces. Future studies should further investigate the potential instream wood drivers in neotropical catchments in order to better understand the differences and similarities here detected between biomes and climatic regions.

Methods of Wood Volume Determining and Its Implications for Forest Transport.

Proper measurements are extremely significant for the forest owner, the harvesting company, the hauler, the final buyer, and the wood processing company. The accuracy of round wood volume determination is of fundamental importance in planning and accounting for individual processes related to the wood trade. It is the basis for determining the maximum quantity in single load of wood that allows for using the permissible total gross vehicle weight. The determination of wood load in cubic meters does not allow unequivocally determining its weight, which often leads to overloading of vehicles. This paper presents a comparison of the photo-optical method for determining the volume of wood to be transported with the real measurement and determination of the weight of a load and the total gross vehicle weight (GVW) with the simultaneous application of conversion factors determining the weight of the load from the volume of wood. The measurement included 23 broadleaf round wood piles (193.73 m3) and 14 coniferous round wood piles (149.23 m3). The measurement error for broadleaf wood piles ranges from −47.67% to 63.16%, and from −43.31% to 24.72% for coniferous wood piles. Determination of the volume of a broadleaf wood pile using the iFOVEA method had an average error of 1.34%, while the Timbeter method had an average error of −1.83%. In the coniferous wood pile measurement, the error is −12.82% and 2.41%, respectively. Verification of the volume of the large-sized wood indicated on the delivery note (reference value) on the log sorting line (by laser scanning) showed larger volumes by 0.10 m3 to 2.54 m3, giving a percentage error of 0.35% and 8.62%, respectively. As a consequence of the application of such methods for determining the weight of wood loads, the transport truck sets are often significantly overloaded, which has a significant impact on the accelerated degradation of roads and safety in traffic and timber transportation.

Rehabilitating Valley Floors to a Stage 0 Condition: A Synthesis of Opening Outcomes

Degraded floodplains and valley floors are restored with the goal of enhancing habitat for native fish and aquatic-riparian biota and the protection or improvement of water quality. Recent years have seen a shift toward “process-based restoration” that is intended to reestablish compromised ecogeomorphic processes resulting from site- or watershed-scale degradation. One form of process-based restoration has developed in the Pacific Northwest, United States, that is intended to reconnect rivers to their floodplains by slowing down flows of sediment, water, and nutrients to encourage lateral and vertical connectivity at base flows, facilitating development of dynamic, self-forming, and self-sustaining river-wetland corridors. Synergies between applied practices and the theoretical work of Cluer and Thorne in 2014 have led this form of restoration to be referred to regionally as restoration to a Stage 0 condition. This approach to rehabilitation is valley scale, rendering traditional monitoring strategies that target single-thread channels inadequate to capture pre- and post-project site conditions, thus motivating the development of novel monitoring approaches. We present a specific definition of this new type of rehabilitation that was developed in collaborative workshops with practitioners of the approach. Further, we present an initial synthesis of results from monitoring activities that provide a foundation for understanding the effects of this approach of river rehabilitation on substrate composition, depth to groundwater, water temperature, macroinvertebrate richness and abundance, secondary macroinvertebrate production, vegetation conditions, wood loading and configuration, water inundation, flow velocity, modeled juvenile salmonid habitat, and aquatic biodiversity.

Moisture and short-term time-dependent behavior of Norway spruce clear wood under compression perpendicular to the grain and rolling shear

ABSTRACT Material properties of wood under compression perpendicular to the grain and rolling shear are important for the engineering design of timber structures. This regards the short-term stiffness and strength, their dependence on the moisture content of wood, as well as the time-dependent behavior. Norway spruce clear wood properties in the transverse plane of wood were studied in an experimental campaign exploiting an earlier developed biaxial test setup. The moisture dependence of the stiffness and strength and the short-term time-dependent creep deformations under compression in the radial direction and under rolling shear were characterized. Loading and unloading stiffness, as well as the strength, were determined in quasi-static tests at five different moisture contents from 4% to 29%. The elastic and viscous stiffnesses were identified in creep tests at three compressive stress levels of 0.50, 0.75, and 1.00 N/mm 2 , and at two rolling shear stress levels of 0.33 and 0.50 N/mm 2 . The test data complements the existing experimental database, especially with novel data regarding the moisture dependence of the rolling shear strength, which showed less moisture dependence than the compressive strength perpendicular to the grain. The results of the creep tests revealed different material properties for the different loading and material directions of wood.

USE OF HOLOGRAPHIC INTERFEROMETRY FOR MONITORING HEAT TRANSFER

In the paper is described possibility of holographic interferometry in research of heat transfer above samples. Experiments with utilization of this method enable to explain many of actions going in environment and in phase interface between material and this environment in transport of heat. The presented experiments are aimed at verifying the possibilities of safe thermal loading of wood using with metal protective plate.

Modernization of mini-tractor for wood skidding

The work was carried out in three directions: changing the rotation system of mini-tractor, installing remote control of the winch and improving the trailer. The modernization of the mini-tractor in all directions was successfully completed, and the research results were patented. Testing of the improved mini-tractor in real working conditions confirmed our expectations. Replacing the rotary mechanism with steering, installing the driver’s seat significantly reduced operator fatigue when wood skidding. Remote control of the winch reduced the time of wood loading on the trailer by 1.7 times compared to the option without using it. The total time to perform entire technology cycle from cutting trees to loading them on the trailer, skidding and unloading is decreased by 19.4%. Changing the design of the trailer allows to exclude the turn of the tractor train along the skidroad with penetration into the forest and facilitate the loading of harvested timber.

Vpliv podnebnih sprememb na dinamiko glivnega razkroja lesa v Sloveniji

The intensity of fungal decay depends mainly on wood species, temperature and precipitation events. To estimate the planned service life of wood and to determine the maintenance intervals of wooden buildings, it is necessary to assess how wood behaves in a given environment. There are a variety of models that have been developed to assess the loading of wood. The approach most commonly used in practice is that developed by Theodore Scheffer. Scheffer proposed a climate index (Scheffer climate index) based on the number of rainy days and monthly average temperatures. Based on these data, Scheffer climate index for chosen locations in Slovenia was calculated. The results of the analysis of climatic conditions show that the Schef%fer climate index is higher than it was decades ago at most of the analysed sites in Slovenia. The intensity of decomposition increased at all analysed locations, with the exception of Portorož. The largest increase in the Scheffer climate index was ob%served in Rateče.

Rotational Rheology of Wood Flour Composites Based on Recycled Polyethylene.

In this paper, we study the effect of the addition of wood flour as a filler in a recycled polyethylene (r-PE) in view of its potential applications in 3D printing. The composites, prepared by melt mixing, are characterized with torque measurements performed during the compounding, dynamic rotational rheology, and infrared spectroscopy. Data show that the introduction of wood results in increased viscosity and in sensible viscous heating during the compounding. The r-PE appear to be stable at temperatures up to 180 °C while at higher temperatures the material shows a rheological response characterized by time-increasing viscoelastic moduli that suggests a thermal degradation governed by crosslinking reactions. The compounds (with wood loading up to 50% in wt.) also shows thermal stability at temperatures up to 180 °C. The viscoelastic behavior and the infrared spectra of the r-PE matrix suggests the presence of branches in the macromolecular structure due to the process. Although the addition of wood particles determines increased viscoelastic moduli, a solid-like viscoelastic response is not shown even for the highest wood concentrations. This behavior, due to a poor compatibility and weak interfacial adhesion between the two phases, is however promising in view of common processing technologies as extrusion or injection molding.