The Low-cost Technical System of Rural Sustainable Wood Construction and its Suitability Based on the Small-diameter Round Timber of Fast-growing Northeast Larch
This paper analyzed practices and future outlooks of log construction from the perspective of Finnish experts through interviews. Key findings highlighted that: (1) interviewed experts emphasized the environmental benefits of log construction; (2) moving log buildings from one place to another was considered a natural way to reuse logs, but several challenges regarding wet areas and incompatibility of different producer profiles were reported; (3) single-material construction of log was stated to have many advantages such as ease of application during erection and relatively long service life; (4) log structures were mostly associated with health, safety, coziness, beauty, and warmth; (5) increasing trend in the use of log construction in large-scale public projects was reported; (6) experts stated that the use of logs in high-rise buildings in Finland is underdeveloped, but hybrid applications using engineered wood products can provide a solution to this issue; (7) modern log cities can be designed with proper solutions, paying attention to several issues e.g., large glass-faced facades; (8) cost competitiveness, familiarity, fire safety, and facade cladding were assessed among the biggest challenges of log construction; (9) issues such as increasing number of contractors specializing in log buildings, robotics in production automation, digitization of manufacturing control were on the future agenda of log construction. It is thought that this study will support the use of logs by contributing to log structures that will be diversified and developed in the Finnish construction market.
The pedestrian-induced instability of the London Millennium Bridge is a widely used example of Kuramoto synchronisation. Yet, reviewing observational, experimental, and modelling evidence, we argue that increased coherence of pedestrians' foot placement is a consequence of, not a cause of the instability. Instead, uncorrelated pedestrians produce positive feedback, through negative damping on average, that can initiate significant lateral bridge vibration over a wide range of natural frequencies. We present a simple general formula that quantifies this effect, and illustrate it through simulation of three mathematical models, including one with strong propensity for synchronisation. Despite subtle effects of gait strategies in determining precise instability thresholds, our results show that average negative damping is always the trigger. More broadly, we describe an alternative to Kuramoto theory for emergence of coherent oscillations in nature; collective contributions from incoherent agents need not cancel, but can provide positive feedback on average, leading to global limit-cycle motion.
PurposeChina has proposed the carbon emission target in 2020, and timber building is one of the solutions to reduce carbon emission in building sector. This study conducts a comparative study to quantitative analysis of the decarbonization potential of timber buildings from a life cycle perspective.Methods
Seven representative demonstration projects with a timber structure in China were selected as research objects. The materials inventory was collected. Based on China’s national standard Standard for Building Carbon Emission Calculation (GB/T51366-2019), the life cycle carbon emissions from all 5 stages, including production, transportation, construction, operation, and demolition stages, are calculated. The assessment results are compared to ordinary reinforced concrete buildings and ultra-low energy buildings.Results and discussionThe findings indicated that carbon emissions in the operation stage of buildings accounted for an average of 87.7% of carbon emission in the total life-cycle of buildings. Compared to ordinary buildings made of reinforced concrete, timber buildings can reduce carbon emissions in the production stage by 64.5%. Therefore, from a life-cycle perspective, 11.0% of carbon emissions can be saved. By upgrading energy efficiency to ultra-low energy buildings, although the carbon emission from building material may increase by 28.5%, the carbon emission is significantly reduced by 39.3% during the operation stage, with a 32.7% reduction for the life cycle.Conclusions
This study provides a life cycle assessment of carbon emission of 7 timber buildings in China. The timber buildings only contribute to the decarbonization for the production stage. Around 11.0% of carbon emissions can be saved for timber structures. Meanwhile, 32.7% more carbon emissions can be saved by upgrading the energy efficiency to ultra-low energy buildings. This study also shows LCA is an effective tool for evaluating the contributions of different aspects and to ensure the achievement of carbon emission targets.
Small-diameter round timber is a kind of by-product mainly from the thinning operation of the plantations. It is plentiful and inexpensive, and is generally destined for non-structural applications. The small-diameter round timber is rarely used as structural members. This study was aimed to provide an innovative but simple way to use the small-diameter round timber as structural members. Three kinds of composite members were developed to be used in light frame wood construction, i.e. the built-up studs, the wood-steel joists and the wood-steel roof trusses. The shearwalls and diaphragms made of the developed composite members were also examined. To facilitate the fabrication, the configurations of these members were described in details. Efforts were also made to investigate the structural performances of these members via full-scale tests. It was found that the developed composite members could be used as substitutes of dimension lumber in the framework of light frame construction. The developed members could be also pre-fabricated as standard components in a mill and assembled on site. As a result, application of small-diameter round timber as structural members developed would be an efficient way to increase use of forest resource from plantation and lower the construction cost of light frame buildings.
Buildings and the construction industry are top contributors to climate change, and structures account for the largest share of the upfront greenhouse gas emissions. While a body of research exists into such emissions, a systematic comparison of multiple building structures in steel, concrete, and timber alternatives is missing. In this article, comparisons are made between mass and whole‐life embodied carbon (WLEC) emissions of building superstructures using identical frame configurations in steel, reinforced concrete, and engineered timber frames. These are assessed and compared for 127 different frame configurations, from 2 to 19 stories. Embodied carbon coefficients for each material and life cycle stage are represented by probability density functions to capture the uncertainty inherent in life cycle assessment. Normalized results show clear differences between the masses of the three structural typologies, with the concrete frame approximately five times the mass of the timber frame, and 50% higher than the steel frame. The WLEC emissions are mainly governed by the upfront emissions (cradle to practical completion), but subsequent emissions are still significant—particularly in the case of timber for which 36% of emissions, on average, occur post‐construction. Results for WLEC are more closely grouped than for masses, with median values for the timber frame, concrete frame, and steel frame of 119, 185, and 228 kgCO2e/m2, respectively. Despite the advantage for timber in this comparison, there is overlap between the results distributions, meaning that close attention to efficient design and procurement is essential. This article met the requirements for a gold–gold JIE data openness badge described in http://jie.click/badges.
The integrated development of transportation and tourism has become a new trend in the transformation and development of the transportation industry. A series of policies issued from the central government to the local government have put forward corresponding requirements for the integrated development of transportation and tourism, the construction of tourism roads, and the upgrading of highway service facilities. As an important window of highway service for tourism, the construction of tourism service area needs to pay more attention to the spiritual needs of tourists and create a “tourist place” with a strong sense of belonging. In the environmental planning and design of tourism service area, the design concept of “place spirit” is presented, which makes the tourism service area have the dual characteristics of external form and place spirit. In the aspects of environmental coordination, space guidance, service function expansion, visual environment, etc., the construction of space environment of tourism service area is strengthened.
Forests and forest industries can contribute to climate change mitigation by sequestering carbon from the atmosphere, by storing it in biomass, and by fabricating products that substitute more greenhouse gas emission intensive materials and energy. The objectives of the study are to specify alternative scenarios for the diversification of wood product markets and to determine how an increasingly diversified market structure could impact the net carbon emissions (NCEs) of forestry in Finland. The NCEs of the Finnish forest sector were modelled for the period 2016–2056 by using a forest management simulation and optimization model for the standing forests and soil and separate models for product carbon storage and substitution impacts. The annual harvest was fixed at approximately 70 Mm3, which was close to the level of roundwood removals for industry and energy in 2016. The results show that the substitution benefits for a reference scenario with the 2016 market structure account for 9.6 Mt C (35.2 Mt CO2 equivalent [CO2 eq]) in 2056, which could be further increased by 7.1 Mt C (26 Mt CO2 eq) by altering the market structure. As a key outcome, increasing the use of by‐products for textiles and wood–plastic composites in place of kraft pulp and biofuel implies greater overall substitution credits compared to increasing the level of log harvest for construction.
Our project is an investigation of the design, shaping, simulation, manufacture, and construction of lightweight load-bearing structural components made of wood-based continuous-fiber textiles. Our aim is to innovatively adapt established concepts in wood construction, such as panelized construction and wood framing, to textile construction. We are developing a continuous filament out of solid wood that can be made into wood-textile structures. Textiles have many advantages: excellent suitability for light construction, versatility of form and function, refined and tested manufacturing and processing technologies, and a characteristic, ever-changing, deeply familiar aesthetic of parallel and crossing threads. Our ultimate goal is to develop a materialefficient, functional, and aesthetically appealing architecture based on solid-wood textiles.
Beside the reduction of greenhouse gas emission the adsorption and bounding of carbon dioxide is also an important issue to protect the environment from irreversible harms. By photosynthesis produced wood material mostly built up from the CO 2 content of the atmosphere and it is stored until burning or natural decay of the material. Log homes sequester significant amount of wood for longer time and the amount in cubic meter and the carbon dioxide equivalence were examined in this case study. Wood content of 80 log homes were investigated and the average of 35.28 m ³ was found. The average stored carbon dioxide per log homes was 31 tons, and there is slight difference between one and two storied buildings 0.214 and 0.284 tons of equivalent carbon dioxide per layout square meter respectively. The ceiling height influences the wood content of the building significantly and the variation is higher in the case of two-storied buildings.
Small diameter logs from juvenile trees are heavily produced during the management of artificial forests around the world. As a kind of plentiful and inexpensive natural resource, the potential was not fully explored. So far the small diameter logs are mainly used as raw materials for products other than building materials. To utilize these small diameter logs originating from juvenile trees as structural members into wood construction, a kind of hybrid built-up column was developed and the performance was investigated experimentally and theoretically. It was found that column had good load-carrying capacity. To apply the developed member in wood construction, the prediction method of the column was proposed. The effective slenderness ratio which took the shear deformations due to the bending of limbs and slip of nail connections between U-shaped nails and limbs into consideration was derived based on mechanics theory. The proposed prediction method was found to have good accuracy in predicting the load-carrying capacity of the hybrid built-up column. This paper can promote the structural application of the small diameter logs originating from juvenile trees.
Woven timber arch bridges date back over 1000 years in China but were only rediscovered in the 1980s. Combining 'beam-weaving' techniques with mortise-and-tenon joints, they provide visually elegant structures with strong mechanical performance. As reported in this paper, the 'warp and weft' design has been enjoying a resurgence in recent years, not just for bridges but also in architecture and furniture. The origins, cultural significance and renaissance of woven arch bridges are explored together with their distinctive structural features and construction methods.
According to the survey and measurement on rural housing in the Northeast severe cold regions of China, this paper analyzed the existing situation and problems of current rural housing in terms of integral development, functional layout, envelop structure, interior thermal environment, heating system and energy utilization etc.. Based on the climatic features of severe cold regions, as well as rural financial and technical conditions, living and production mode, residential construction characteristics and existing resource status etc., the feasible approaches of achieving building energy saving has been proposed, thus acting as a guidance for new rural housing design in severe cold regions.
The structural use of round timber has been considered competitive in terms of both economics and sustainability due to the low energy consumption required for processing it. However, structural uses of wood in round and sawed forms require knowledge of wood properties, which makes the grading of these properties essential. In Brazil, an ultrasound grading standard for wood was proposed based on tests of lumber from tropical species with an average age of approximately 45 years. The objective of the present study was to evaluate whether the grades proposed by this standard could be used, either directly or by applying correction factors, to grade round timber derived from a planted Eucalyptus forest. For this evaluation, round timber with different diameters was tested using ultrasound at saturated moisture content (MC) greater than 30% and at environmental equilibrium (an MC of approximately 12%). Static bending tests were conducted only when the MC was at the environmental equilibrium (approximately 12%). Although it is necessary to validate the conclusions with a larger data set, the results indicate that due to the correlation between the diameter of round timber and its acoustic and mechanical properties, any round timber grading system must consider the diameter of the pieces. The larger the diameter of the round wood is, the greater the difference between the actual velocity in the log and the velocity expected by the grading standard that considers the stiffness.
Trees, and their derivative products, have been used by societies around the world for thousands of years. Contemporary construction of tall buildings from timber, in whole or in part, suggests a growing interest in the potential for building with wood at a scale not previously attainable. As wood is the only significant building material that is grown, we have a natural inclination that building in wood is good for the environment. But under what conditions is this really the case? The environmental benefits of using timber are not straightforward; although it is a natural product, a large amount of energy is used to dry and process it. Much of this can come from the biomass of the tree itself, but that requires investment in plant, which is not always possible in an industry that is widely distributed among many small producers. And what should we build with wood? Are skyscrapers in timber a good use of this natural resource, or are there other aspects of civil and structural engineering, or large-scale infrastructure, that would be a better use of wood? Here, we consider a holistic picture ranging in scale from the science of the cell wall to the engineering and global policies that could maximise forestry and timber construction as a boon to both people and the planet.
Even though tightened building energy efficiency standards are implemented periodically in many countries, existing buildings continually consume a momentous quota of the total primary energy. Energy efficiency solutions range from material components to bulk systems. A technique of building construction, referred to as prefabricated architecture (prefab), is increasing in reputation. Prefab encompasses the offsite fabrication of building components to a greater degree of finish as bulk building structures and systems, and their assembly on-site. In this context, prefab improves the speed of construction, quality of architecture, efficiency of materials, and worker safety, while limiting environmental impacts of construction, as compared to conventional site-built construction practices. Quite recently, a 57 story skyscraper was built in 19 days using prefabricated modules. From the building physics point of view, the bulk systems and tighter integration method of prefab minimizes thermal bridges. This study seeks to clearly characterize the levels of prefab and to investigate the performance of modular prefab; considering acoustic constrain, seismic resistance, thermal behavior, energy consumption, and life cycle analysis of existing prefab cases and, thus, provides a dynamic case study-based review. Generally, prefab can be categorized into components, panels (2D), modules (3D), hybrids, and unitized whole buildings. On average, greenhouse gas emissions from conventional construction were higher than for modular construction, not discounting some individual discrepancies. Few studies have focused on monitored data on prefab and occupants' comfort but additional studies are required to understand the public's perception of the technology. The scope of the work examined will be of interest to building engineers, manufacturers, and energy experts, as well as serve as a foundational reference for future study.
The recent energy and environmental crises and corresponding regulations have increased interest in replacing conventional materials with sustainable materials in construction. Due to the outstanding properties of wood, such as recyclability, reusability and natural renewability, it is considered a sustainable material. In addition, wood has a high strength-to-weight ratio and outstanding acoustic and thermal insulation properties, which make it an appropriate construction material in numerous applications, including in main structural members such as beams, columns and flooring systems as well as in non-structural members, such as windows, doorframes and insulating envelopes. Recent advancements in the production of engineering wood and efficient adhesives have made the fabrication of structural members with large cross sections, long spans and structural properties comparable to steel and reinforced concrete feasible and cost-effective. As a result, interest in long-span timber buildings has increased greatly. In this paper, a comprehensive review of research studies investigating various aspects of long-span timber structures, including material properties, structural performance and sustainability, are presented. In particular, over 100 research papers were systematically reviewed to study the constructability of long-span flooring systems. The techniques and methodologies available for the fabrication, analysis and experimental investigations of structural flooring systems are also reviewed in detail. Overall, this comprehensive review helps to achieve a greater understanding of structural static and dynamic responses of long-span timber flooring systems, and undertaking the challenges and opportunities presented in this paper could significantly contribute to the improvement of the structural design to reach optimised, sustainable, and constructible systems.
The construction industry is one of the largest contributors of CO2 emissions. To achieve the goal of carbon peaking by 2030 and carbon neutrality by 2060, China needs to develop carbon reduction pathways for the construction industry. Bamboo is believed to be one of the most appropriate candidates for afforestation to reduce CO2 concentration and alleviate the effects of climate change. It is also an ideal building material with high tensile and compressive strengths. However, the carbon emissions and storage of bamboo building materials have not been well understood. This study aims to quantify the CO2 emissions and carbon storage of bamboo building materials and to analyse the potential to reduce these carbon emissions. Results show that the planting phase contributes the largest amount of carbon uptake whilst the production phase contributes the largest amount of carbon emissions. ‘Carbonisation’ is found to be the production process with the highest carbon emissions, followed by ‘antimould, anticorrosion and drying treatment’ and ‘glue application’. Three strategies that are useful in reducing carbon emissions are proposed and validated. After the implementation of the proposed strategies, the average and median amount of carbon emissions changed from 1291.63 and 1290.75 kg to 1088.36 and 1090.29 kg. Taking all phases into account, one cubic meter of bamboo assembled components can reduce 249.92 kg CO2 from the atmosphere. Compared to dimensioned lumber, engineered lumber, cement, steel, timber, hempcrete, bamboo building materials have the highest CO2 emissions and carbon storage. The carbon storage of bamboo assembled components per tonne is around 140 kg more than that of timber per tonne. This study is expected to assist not only researchers in understanding the carbon reduction potential of bamboo building materials but also practitioners in promoting bamboo building-based carbon reduction pathways.
Polymerbeton ist ein hochleistungsfähiges Material, welches im Bau‐ und Maschinenbauwesen bereits eine vielfältige Anwendung erfährt. Im Bauwesen kann das Potenzial des Materials allerdings bislang nicht gänzlich genutzt werden. Ursache ist neben fehlenden normativen Grundlagen für das Material und dessen Bemessung auch eine fehlende Klassifizierung des Materials nach den relevanten bautechnischen Normen. Gerade im Anwendungsbereich tragender Bauteile, wie z. B. hochbeanspruchter Knoten‐ und Anschlussgeometrien von Stabtragwerken und Ingenieurkonstruktionen, liegt jedoch das Potenzial des Polymerbetons mit seiner hohen Druck‐ und Biegezugfestigkeit. Um die Anwendungsmöglichkeiten im Bauwesen entsprechend zu erweitern, werden maßgebende Materialparameter eines handelsüblichen Polymerbetons, wie die Druck‐, Biegezug‐, Zugfestigkeit, der E‐Modul sowie die Verbundfestigkeit zum gerippten Betonstahl, nach bautechnischen Normen geprüft und charakteristische Materialkennwerte abgeleitet. Die Untersuchungen variieren nach Probekörpergeometrien, Betonalter und Temperatur. Die Einordnung und Klassifizierung der Materialeigenschaften erfolgt im Vergleich mit normal‐, hoch‐ und ultrahochfesten Betonen.
Associated with the continuing increase of construction activities such as infrastructure projects, commercial buildings and housing programs, Bangladesh has been experiencing a rapid increase of construction and demolition (C&D) waste. Till now, the generation rate of C&D waste has not been well understood or not explicitly documented in Bangladesh. This study aims to provide an approach to estimate C&D waste generation using waste generation rates (WGR) through regression analysis. Furthermore, analyses the economic benefit of recycling C&D waste. The results revealed that WGR 63.74 kg/m 2 and 1615 kg/m 2 for construction and demolition activities respectively. Approximately, in financial year (FY) 2016, 1.28 million tons (0.149 construction and 1.139 demolition) waste were generated in Dhaka city, of which the three largest proportions were concrete (60%), brick/block (21%) and mortar (9%). After collection they were dumped in either landfills or unauthorized places. Therefore, it can be summarized as: waste is a resource in wrong place. The results of this study indicate that rapid urbanization of Dhaka city would likely experience the peak in the generation of C&D waste. This paper thus designates that C&D waste recycling is an entrepreneurial activity worth venturing into and an opportunity for extracting economic and environmental benefits from waste. The research findings also show that recycling of concrete and brick waste can add economic value of around 44.96 million USD. In addition, recycling of C&D waste leads to important reductions in CO 2 emissions, energy use, natural resources and illegal landfills. Therefore, the findings of WGR and economic values provide valuable quantitative information for the future C&D waste management exercises of various stakeholders such as government, industry and academy.
Forests worldwide are overstocked with small-diameter trees, putting them at increased risk of disease, insect attack, and destructive high-intensity wildfires. This overstocking is caused primarily by the low market value of these small-diameter trees, which are generally unsuitable for sawn timber production and yield low prices when sold for biomass fuel, paper, or fibre-based engineered timber products. Considerable research in recent decades has demonstrated the potential for these small-diameter trees to be used in minimally processed round segments as structural elements in buildings, bridges, towers, and other infrastructure. Recent structures have also demonstrated the use of trees with major curvature and branching, which are also of low market value, in their round form as primary structural elements. Such “whole timber” construction serves as a low-cost, low-impact building system while providing revenue to forest owners to conduct harvests of low-value trees as required for sustainable forest management. This paper reviews developments in whole timber construction, presenting new non-destructive evaluation techniques, digital survey, design and fabrication methods, new processing technologies, and a diverse range of novel connection types and structural systems. It is shown that the key materials characterisation, processing, and design challenges for whole timber construction have been largely addressed, and that whole timber has the potential to be an important complement to other timber products in construction globally in the coming decades. It is recommended that future work focus on exploiting new digital technologies and scaling whole timber structural applications through increased prefabrication.
I. II. III. IV. V. VI. VII. References SUMMARY: The woody stems of trees perceive gravity to determine their orientation, and can produce reaction woods to reinforce or change their position. Together, graviperception and reaction woods play fundamental roles in tree architecture, posture control, and reorientation of stems displaced by wind or other environmental forces. Angiosperms and gymnosperms have evolved strikingly different types of reaction wood. Tension wood of angiosperms creates strong tensile force to pull stems upward, while compression wood of gymnosperms creates compressive force to push stems upward. In this review, the general features and evolution of tension wood and compression wood are presented, along with descriptions of how gravitropisms and reaction woods contribute to the survival and morphology of trees. An overview is presented of the molecular and genetic mechanisms underlying graviperception, initial graviresponse and the regulation of tension wood development in the model angiosperm, Populus. Critical research questions and new approaches are discussed.
Portuguese pine forests frequently have high density due to the large number of young trees, which are maintained in the stands due to the high costs of thinning operations and the lack of financial return provided by the markets available for smalldiameter poles. With this problem in mind, a national project was launched to investigate the use of Maritime pine smalldiameter poles in structural applications. It is believed that this utilization could promote stand thinning operations by providing extra income to forest owners. Poles for the study were collected in an interior central region of Portugal and visually graded according to European standard EN1310. Poles were then tested (bending and compression) following European standard EN14251.The results obtained are presented and discussed along with the results obtained for round timber from other wood species and for Maritime pine strength graded structural timber with rectangular cross section. Considering future development of national strength grading standards (based on the results of this project), some correlations are presented between wood features and mechanical properties and between bending strength and stiffness. Good correlations were obtained between bending strength, density, and local modulus of elasticity (MOE). A significant difference in the bending strength between round and rectangular cross sections was observed but not for MOE.
Forest managers have identified forest stands overstocked with small-diameter trees as a critical forest health issue. Overstocked stands are subject to attack by insects and disease and, as a result of the heavy fuel load, risk total destruction by fire. Prescribed burning is an economic tool for suppressing the growth of brush and tree seedlings, but its use is often restricted for environmental reasons. Forests that contain a heavy fuel load extending into the canopy must be thinned to reduce the fuel load before prescribed burning can be used to avoid future loss caused by fire, insects, and disease. One way to help recover the cost of mechanical thinning is to promote value-added structural uses of the small-diameter round timber to be removed. Although the cost of mechanical removal thinning can be partially justified on the basis of time and money saved by preventing future resource destruction, savings based on conjecture and probability of occurrence are difficult to quantify. Value-added uses of this material can provide immediate return in the form of increased revenue for thinnings and rural economic development. This paper is an overview of the options for round timber structural applications and contains recommendations for research needed to promote acceptance of engineered applications.
The wind environment around residential building groups is increasingly concerned, while the dwelling groups as the elementary unit of planning design, its quality of surrounding wind environment will directly affect people's life. This study based on the climatic conditions of severe cold regions, selects four dwellings groups with different openings scale and position as the research objects, and then simulates and analyzes the wind speed distribution characteristics of each pattern. Meanwhile, it extracts the wind speed values of one hundred points of each pattern and applies the coefficient of uniformity method to the ecological evaluation. It has been found that grouping pattern of buildings has a dramatic effect on the resulting airflow behavior. Configurations that contain a T-shaped central space with small opened side can effectively prevent and contain airflow in the site offer. The interactive influence between layout of dwelling groups and wind environment are explored, so as to provide basis for the planning design of dwelling groups.
When we are in the face of China's construction industry the status quo, which gradually lose their original architectural features in the tide of globalization,many scholars have had many discussions and research for this problem, however, specific according to the characteristics of the local-style dwelling houses research areas, is still inadequate. In the article, we research on the characteristic of Fujian dwellings ,which is one of South building dwellings in China, and combined with China's current situation of building development, try these two architectural form fusion, to create a new era of construction combing with Chinese characteristics and culture.
The purpose of this study is to suggest practical planning principles, which are absent in landscape ecology planning, according to which the spatial completeness of the watershed is derived from native Korean Feng-Shui (
). Landscape ecology planning principles are used widely in contemporary planning projects in terms of patch, corridor, matrix and network of landscape pattern. However, landscape indices for planning principles are complicated and constrained, and so are limited to applications for site and eco-village plannings. Native Korean Feng-Shui is different from Chinese Feng-Shui in that it is aimed at theoretical completeness in terms of aspect and topographical shape, based on the concept of ideal Myung-dang (
) to complete the space, according to local conditions in the physiognomy of the watershed. The complementary method is called Bi-bo (
) in native Korean Feng-Shui. These principles have been applied in traditional Korean villages, leading to consistent location choices and fractal patterns in land use. Furthermore, Bi-bo woodlands and ponds have been introduced to achieve spatial completeness in the landscape structure of the village.
This article presents the results and the comments of a sampling of 80 spruce conical roundwoods (tree trunks with the bark removed) of structural sizes tested in bending. Pressure impregnated samples were prepared with and without heart holes and paired with the untreated samples. Treatment effects have been studied in order to investigate their influences on the mechanical behavior. With a non-destructive evaluation by ultrasound, the mechanical results have been compared with an equivalent sawn timber series to analyze the effect of the form. The results show a negative influence of about 10% for the pressure-impregnated treatment on the mechanical properties only and up to 20% for the samples which were associated with pinholes for the heart treatment. On the other hand, the form effect increases the mechanical characteristics by 30% when compared to the square cross section. These results can be explained by a semi-ductile phase observed before failure. This conical roundwood form contributes to optimize the mechanical behavior linked to the anisotropic conditions where the grain is continuous and has a zero angle value with the longitudinal axis.
The use of small-diameter timber in construction has been investigated. The aim of the work is to increase the use of the wood harvested in forest thinning in construction applications. The work has covered a wide range of aspects, from availability of the material to design of the structures. This publication summarizes the results in following areas: availability, dimensions and quality of conifers harvested in forest thinning, cost of harvesting and woodworking, comparison of drying methods: seasoning, warm-temperature and hightemperature kiln-drying, improving durability, strength of round small-diameter conifers, potential types of structures to be built from round timber and new mechanical joints.
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