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Export Competitiveness and Sustainable Development of the Ukrainian Timber Industry
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作者 Anastasiia Shapiro 《Open Journal of Applied Sciences》 2024年第10期2777-2789,共13页
This paper conducts a comprehensive analysis of the export dynamics within the Ukrainian timber industry, emphasizing its pivotal role in the national economy. The study begins by outlining the research objectives, co... This paper conducts a comprehensive analysis of the export dynamics within the Ukrainian timber industry, emphasizing its pivotal role in the national economy. The study begins by outlining the research objectives, context, and innovative methodologies, setting the stage for a deep dive into the theoretical underpinnings of sustainable and competitive trade. It explores Ukraine’s rich forest biodiversity across varied vegetation zones and its geopolitical significance. Detailed evaluations of forest resource management, policy frameworks, and institutional support form the core of the analysis. Challenges such as imbalanced export structures and legal inconsistencies are critically examined. The research employs trade gravity models and competitive indicators like the Revealed Comparative Advantage (RCA) and Market Share (MS) to assess factors influencing exports and to forecast potential growth areas. The findings inform strategic recommendations aimed at enhancing export capacity through market diversification, brand development, and legal stability. The conclusion highlights the need for strategic interventions to harness Ukraine’s timber resources sustainably, balancing economic gains with environmental stewardship. 展开更多
关键词 Ukrainian timber Industry Export Dynamics Export Competitiveness Sustainable Trade Forest Resource Management
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Evaluation of Mechanical Properties of Cross-Laminated Timber with Different Lay-ups Using Japanese Larch 被引量:4
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作者 Yingchun Gong Fenglu Liu +3 位作者 Zhaopeng Tian Guofang Wu Haiqing Ren Cheng Guan 《Journal of Renewable Materials》 SCIE 2019年第10期941-956,共16页
Japanese larch is one of the main plantation tree species in China.A lack of engineered wood products made by Japanese larch,however,limits its application in wood stnuctures.In this study,based on optimum process par... Japanese larch is one of the main plantation tree species in China.A lack of engineered wood products made by Japanese larch,however,limits its application in wood stnuctures.In this study,based on optimum process parameters,such as pressure(12 MPa),adhesive spread rate(200 g/m^(2))and adhesive(one-component polyurethane),the mechanical properties of Japanese larch-made cross-laminated timber(CLT)with different lay-ups were evaluated by means of the static method.Results of this study showed that variations in lay-ups significantly affected the mechanical properties of CLT.The strength and modulus of bending and parallel compression for CLT increased with the thickness of lumber,while that of bending,parallel compression and rolling shear all decreased with the number of layers.Thickness,layup orientation and the number of layers all had an impact on the strength of CLT.Failure modes obtained from numerical simulation were basically the same as those of experimental tests.There was also strong alignment between theoretical value and test value for effective bending stifness and shear stifness.Thus,the shear analogy method can be used to predict the mechanical properties of CLT effectively.This study proved great potential in using Japanese larch wood for manufacturing CLT due to its good mechanical properties. 展开更多
关键词 cross-laminated timber mechanical properties lay-ups failure mode shear analogy
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Bending,Compression and Bonding Performance of Cross-Laminated Timber(CLT)Made from Malaysian Fast-Growing Timbers
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作者 Norshariza Mohamad Bhkari Lum Wei Chen +4 位作者 Anis Azmi Muhammad Shaiful Nordin Norman Wong Shew Yam Zakiah Ahmad Lee Seng Hua 《Journal of Renewable Materials》 SCIE EI 2022年第11期2851-2869,共19页
This study investigated the bending,compression as well as the bonding performance of CLT panels made from fast-growing timber species,i.e.,Laran(Neolamarckia cadamba)and Batai(Paraserianthes falcataria).The variables... This study investigated the bending,compression as well as the bonding performance of CLT panels made from fast-growing timber species,i.e.,Laran(Neolamarckia cadamba)and Batai(Paraserianthes falcataria).The variables studied were timber species(Laran and Batai),layers of lamination(3-layer and 5-layer),loading direction in bending(in-plane and out-of-plane),loading direction in compression(x-,y-,and z-axis)and different treatment conditions for bonding performance test.The desired outputs of this study were bending and compression properties(strength and stiffness)as well as bonding performance(block shear strength,wood failure percentage and delamination value).The bending and compression test were conducted according to EN16351:2015 and EN408:2012,respectively.On the other hand,the bonding performance test was determined by block shear and delamination test based on EN16351:2015 and EN14374:2004,respectively.Prior to block shear test,the samples were subjected to three different treatment conditions.The results showed that CLT made from 3-layer Laran timber,loaded at out-of-plane direction exhibited the highest bending properties.Contrarily,CLT made from 5-layered Batai timber,loaded at in-plane direction showed the lowest bending properties.Laran samples for compression loaded at x-axis exhibited the best compressive properties.Generally,Laran CLT showed greater bonding performance determined by shear test compared to Batai CLT for both 3-and 5-layer panels.On the contrary,delamination results showed that Batai CLT demonstrated better bonding performance compared to Laran CLT.In terms of bonding performance measured by wood failure percentage(WFP),most samples under various treatment conditions showed WFP≥80%except for samples under wet condition with WFP≤60%. 展开更多
关键词 cross-laminated timber plantation timber flexural performance bonding performance
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Comparative Study on Various Strength Parameters of Structural Elements Made from Cross-Laminated Timber
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作者 Mohammad Anwar-Us-Saadat Janeshka Goonewardena +2 位作者 Bidur Kafle Mahmud Ashraf Mahbube Subhani 《Journal of Renewable Materials》 SCIE EI 2022年第6期1575-1606,共32页
Cross laminated timber(CLT)is an innovative and environment friendly engineered timber product with superior structural performance.CLT offers strong resistance against both in-plane and out-of-plane loading.Hence,it ... Cross laminated timber(CLT)is an innovative and environment friendly engineered timber product with superior structural performance.CLT offers strong resistance against both in-plane and out-of-plane loading.Hence,it is widely used as floors,roofs or wall elements.Considerable experimental research on CLT under various loading conditions has been done in the recent past.This article presents a comprehensive review of various design methods to determine basic mechanical properties such as tension,compression and rolling shear strength of CLT with primary focus on Norway spruce.All relevant experimental data available from existing literature were collated and consequently been used to evaluate the performance of various methods to design CLT structures.The comparison revealed that different methods show considerable variance in predicting the capacity of CLT panels due to the variation in timber species,which affects the corresponding mechanical properties of the lamella.In addition to species,rolling shear properties can also vary considerably depending on the type of experimental technique used for testing.A predictive model has also been proposed to correlate rolling shear strength obtained from shear analogy method to that obtained using planar shear. 展开更多
关键词 cross-laminated timber mass timber mechanical strength rolling shear strength planar shear test short span bending test
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Evaluation of the Out-of-Plane Shear Properties of Cross-Laminated Timber
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作者 Yin Yang Xiaoyan Cao +2 位作者 Zhiqiang Wang Zhijun Liang Jianhui Zhou 《Journal of Renewable Materials》 SCIE 2019年第10期957-965,共9页
The out-of-plane shear properties of cross-laminated timber(CLT)substantially influence the overall mechanical properties of CLT.Various testing methods and theories related to these properties have recently been deve... The out-of-plane shear properties of cross-laminated timber(CLT)substantially influence the overall mechanical properties of CLT.Various testing methods and theories related to these properties have recently been developed.The effects of the number of layers(three and five layers)and testing method(short-span three-and four-point bending tests)on the out-of-plane shear properties of CLT were evaluated.The out-of-plane shear strength values were calculated based on different theories for comparison.The failure mode in the short-span four-point bending(FPB)method was mainly the rolling shear(RS)failure in the cross layers,indicating that the FPB method was appropriate to evaluate the RS strength of CLT.The out-of-plane shear capacity obtained using the three-point bending(TPB)method was higher than that tested by the FPB method.The testing methods significantly influenced the out-of-plane shear capacity of the three-layer specimens but not that of the five-layer specimens.With an increase in the number of layers,the out-of-plane shear strength of the specimens decreased by 24%.A linear correlation was found among the shear strength values obtained from different theories. 展开更多
关键词 cross-laminated timber out-of-plane shear properties testing methods failure modes
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Understanding the Impacts of Plant Capacities and Uncertainties on the Techno- Economic Analysis of Cross-Laminated Timber Production in the Southern U.S.
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作者 Zhenzhen Zhang Kai Lan 《Journal of Renewable Materials》 SCIE EI 2022年第1期53-73,共21页
Understanding the economic feasibility of cross-laminated timber(CLT),an emerging and sustainable alternative to concrete and steel,is critical for the rapid expansion of the mass timber industry.However,previous stud... Understanding the economic feasibility of cross-laminated timber(CLT),an emerging and sustainable alternative to concrete and steel,is critical for the rapid expansion of the mass timber industry.However,previous studies on economic performance of CLT have not fully considered the variations in the feedstock,plant capacities,manu-facturing parameters,and capital and operating costs.This study fills this gap by developing a techno-economic analysis of producing CLT panels in the Southern United States.The effects of those variations on minimum sell-ing price(MSP)of CLT panels are explored by Monte Carlo simulation.The results show that,across all the plant capacities from 30,000 to 150,000 m^(3)/year,the MSP ranges from$345 to$609/m^(3) with a±6%–9%range caused by the variations in feedstocks,key manufacturing parameters,capital and operating cost.The MSP decreases sig-nificantly along the increasing capacities.A sensitivity analysis exhibits that the lumber price,lumber preparing loss,plant capacity,and the installed costs of layering and gluing,finishing,and miscellaneous,are the top driving factors to CLT MSP.Supported by Geographic Information System,this study also studies the transportation cost of delivering CLT to customers under three CLT demanding levels(1%,5%,15%).The results show that the trans-portation cost is 1%–8%of the MSP.Lower demanding level or higher plant capacity can increase the transporta-tion cost due to average longer delivering distance.When considering the delivered cost that sums MSP and transportation cost,larger plant capacity does not necessarily generate lower delivered cost. 展开更多
关键词 cross-laminated timber techno-economic analysis plant capacity uncertainty minimum selling price
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Mechanical Experimental Study on Tensile Bolted Connections of Cross-laminated Timber
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作者 Chenxiao Su Haibei Xiong 《Structural Durability & Health Monitoring》 EI 2020年第1期81-94,共14页
In order to explore a kind of high-strength,earthquake-resistant,eco-nomical and suitable connection,4 groups of cross-laminated timber wall-to-floor and wall-to-wall bolted connections were tested under monotonic and... In order to explore a kind of high-strength,earthquake-resistant,eco-nomical and suitable connection,4 groups of cross-laminated timber wall-to-floor and wall-to-wall bolted connections were tested under monotonic and cyclic load-ing.The defommation characteristics and failure modes of the cross-laminated tim-ber wall-to-floor and wall-to-wall bolted connections were exploited.Load-slip curves,bearing capacity,yielding point,stiffness and ductility of each group of specimens were analyzed.The test results indicate that the loading process of cross-laminated timber bolted connections under tension can be categorized as five stages,namely the elastic stage,the slip stage,the embedding stage,the yield-ing stage and the ultimate stage.The ultimate tensile capacity of cross-laminated timber bolted wall-to-floor connections is 2.67 times that of the wall-to-wall bolted connections.Compared with cross-laminated timber self-tapping screwed connections,the ultimate tensile capacity of the cross-laminated timber wall-to-floor bolted connections is 2.70 times that of the self-tapping screwed connec-tions,and the ultimate tensile capacity of the cross-laminated timber wall-to-wall bolted connections is 3.83 times that of the self-tapping screwed connections.The crosslaminated timber bolted connections have larger yielding displacement and wider plastic range,and they are more energy dissipative and more ductile.Furthermore,the cost of the cross-laminated timber wall-to-floor bolted connec-tions is 46%that of the self-tapping screwed connections,while the cost of cross-laminated wall-to-wall bolted connections is 53%that of the self-screwed connections. 展开更多
关键词 cross-laminated timber bolted connections mechanical properties economical and suitable
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Analysis of Crack Expansion and Morphology of Cross-Laminated Timber Planar Shear Test
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作者 Yujie Huang Yifan Zhang +3 位作者 Zheng Wang Assima Dauletbe Yao Lu Zhaoyu Shen 《Journal of Renewable Materials》 SCIE EI 2022年第3期849-870,共22页
To describe the dynamic cracking process of the CLT vertical layer,the correlation between a load-displacement curve,specimen cracking,and planar shear failure mechanism of the CLT were explored.A three-point bending ... To describe the dynamic cracking process of the CLT vertical layer,the correlation between a load-displacement curve,specimen cracking,and planar shear failure mechanism of the CLT were explored.A three-point bending test and an improved planar shear test are used to evaluate the shear performance of the CLT.In this study,the load-displacement curve is recorded,the experimental part is synchronized with the video,the dynamic process of cracking of the vertical layer is observed and analyzed throughout the test.From the load-displacement curve,the image characteristics of the initial cracking and the sudden increase of the cracking of the specimen are summar-ized.The description results of the whole dynamic process of the CLT vertical layer cracking are analyzed by pla-nar shear strength value,cracking phenomenon,and azimuth angle of cracking surface.The main conclusions show that the three-point bending test and the improved plain shear test can be used to test the plain shear strength of the CLT,with a difference of only 5.7%.The original crack and the new crack expansion account for 18.9%and 81.1%of the main cracking surface,respectively.And the vertical layer of the CLT specimen under three-point bending has three cracking morphologies,such as radial shake,ring shake,neither along with the radial shake nor along with the ring shake.The azimuth angle of the cracking surface of the CLT vertical layer under planar shear is quite consistent with the first main plane azimuth of the vertical layer of the CLT specimens under the three-point bending test and the shearing test.The shape in the cracking direction of the left half-span or the right half-span of the vertical layer of the specimen is similar to the Chinese character eight. 展开更多
关键词 cross-laminated timber planar shearing performance three-point bending test improved planar shear test crack expansion dynamic process
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Experimental Investigation on the Strength and Ductility Performance of Steel-Timber-Steel Joints with Screw and Steel-Tube Fasteners
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作者 Huifeng Yang Mingwang Wu +3 位作者 Rixin Gu Hang Cao Kai Xiao Benkai Shi 《Journal of Renewable Materials》 EI 2023年第12期4175-4195,共21页
This article presents experimental results of steel-timber-steel(STS)joints loaded parallel to grain.Eight groups of specimens were designed,and tensile tests were performed.The fastener types and fastener numbers wer... This article presents experimental results of steel-timber-steel(STS)joints loaded parallel to grain.Eight groups of specimens were designed,and tensile tests were performed.The fastener types and fastener numbers were considered to evaluate the tensile strengths and ductility performances of the STS joints.The screws with 6 mm diameter and the innovative steel-tubes with 18 mm diameter were adopted as connecting fasteners.The experimental results were discussed in terms of yielding and ultimate strengths,slip stiffness,and ductility factors.The ductility classification and failure mechanisms of each group of specimens were analyzed.It was demonstrated that the STS joint with large diameter steel-tubes showed acceptable ductility,which was close to the ductility of the STS joint with small diameter screws,thanks to the hollow structure of the steel-tube.The theoretical strengths of various failure modes for the joints with small diameter screws or large diameter steel-tubes were calculated and compared with the experimental results.The ductile performance of the STS joint was discussed by comparing the theoretical strengths of various failure modes.The effective number of the STS joint with multifasteners was also analyzed by considering the failure mechanisms in aspects of tensile strength and slip stiffness. 展开更多
关键词 Steel-timber-steel joint SCREW steel-tube DUCTILITY experimental investigation timber structure
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Determination of the Properties of Some Selected Timber Species for Structural Application
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作者 Asimiyu Amobi Oyediran Catherine Mayowa Ikumapayi Babatola Olufemi 《World Journal of Engineering and Technology》 2023年第2期319-334,共16页
One of the alternative sustainable and green construction materials to concrete is timber. Timber is of numerous varieties, and this acts as a barrier to the extent of its usage, especially in structural application. ... One of the alternative sustainable and green construction materials to concrete is timber. Timber is of numerous varieties, and this acts as a barrier to the extent of its usage, especially in structural application. Despite many researches on wood’s mechanical and physical properties, only a few are geared toward the structural application of wood. The present work investigated the mechanical properties of five timber species;Gmelina arborea, Tectona grandis (Teak), Terminalia superba (Afara), Ayin (Anogeissus leiocarpus), and Acacia (Robinia pseudoacacia), to determine their suitability for constructing long-span roof trusses. These are available in the South Western part of Nigeria. Their mechanical properties;bending strength, compressive strength, shear strength, tensile strength, Modulus of Elasticity (MOE), Modulus of Rupture (MOR), and density, were determined in the laboratory. The results obtained showed that all the timber types, except Terminalia superba (Afara), have higher values of mechanical properties than the values that are obtainable for classes of strength D30 to class D70 in the British Code of Practice. It means these species are of higher quality than the stipulated strength classes in the British code. The results also show that the order of relevance of the species for structural design (or work) is Acacia (Robinia pseudoacacia), Ayin (Anogeissus leiocarpus), Gmelina Arborea, and Tectona grandis (Teak). Terminalia superba (Afara) is not recommended for structural works. 展开更多
关键词 timber Wood Species Bending Strength Compression Mechanical Properties
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An Experimental Study of Composite Columns Filled with Eucalyptus nitens Timber under Axial Compression
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作者 Yingyao Cheng Xudong Chen +2 位作者 Huaming An Huimin Wang Kai Tao 《Journal of Renewable Materials》 SCIE EI 2023年第2期825-836,共12页
Eucalyptus nitens(E.nitens)has been much used for producing paper but also shows promise for structural applications.In this study,static compressive tests were undertaken to examine its suitability to be used in an i... Eucalyptus nitens(E.nitens)has been much used for producing paper but also shows promise for structural applications.In this study,static compressive tests were undertaken to examine its suitability to be used in an innovative composite column.The composite column was comprised of a rectangular steel tube with E.nitens timber infill.The nonlinear compressive behaviour of the composite column filled with E.nitens wood for both dry and wet conditions was examined.The same tests on rectangular steel tubes and bare dry and wet E.nitens samples were also undertaken as a comparison.For samples with different conditions,the ultimate capacity was evaluated and the effect of each condition on the compressive behaviour of the composite column was clarified.The steel tubes showed greater ductile behaviour,and more ductility was found in the wet samples.The steel tubes with E.nitens timber infill samples exhibited a greater linear elastic range connected with higher maximum loads,while the bare timber samples could support only lower maximum loads.The results from this research were promising for the use of rectangular steel tubes with E.nitens timber infill in structural applications. 展开更多
关键词 Hollow steel tubes EUCALYPTUS high moisture content composite column with timber infill compression
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Verification of Depth Adjustment Factor in Eurocode 5 for Tropical Hardwood Timbers
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作者 Adnie Baharin Muhammad Amirul Akmal Rosli +4 位作者 Norshariza Mohamad Bhkari Lum Wei Chen Anis Azmi Muhammad Shaiful Nordin Zakiah Ahmad 《Journal of Renewable Materials》 EI 2023年第9期3533-3546,共14页
The depth adjustment factor for bending strength stated in Eurocode 5(EC5)is only applicable to timbers having a characteristic density below 700 kg/m^(3).However,most Malaysian timbers are hardwood,some with a charac... The depth adjustment factor for bending strength stated in Eurocode 5(EC5)is only applicable to timbers having a characteristic density below 700 kg/m^(3).However,most Malaysian timbers are hardwood,some with a characteristic density reaching above 700 kg/m^(3).Therefore,the objective of this study was to examine whether the depth adjustment factor stipulated in EC5 is valid for Malaysian hardwood timbers.Six timber species were selected for this study,namely Kapur(Dryobalanops C.F.Gaertn.),Kempas(Koompassia Maingay ex Benth.),Keruing(Dipterocarpus C.F.Gaertn.),Light red meranti(Shorea Roxb.ex C.F.Gaertn.),Geronggang(Cratoxylum Blume)and Balau(Shorea Roxb.ex C.F.Gaertn.).The determination of bending strength and characteristic density was conducted according to BS EN 408:2010 and BS EN 384:2016,respectively.A graph for mean bending strength vs.(150/h)was plotted for each timber species.The power function was selected to analyze the relationship between the two variables.The power of the regression equations varied depending on the characteristic density of the timber species.For species with a characteristic density below 700 kg/m^(3),such as Kapur,Keruing,and Light red meranti,the power was between 0.16 to 0.17.In contrast,for species having a characteristic density above 700 kg/m^(3),namely Kempas and Balau,the power was higher at 0.23 and 0.24,respectively.Geronggang was an exception to this pattern.These values are close to the depth adjustment factor given in EC5,which is 0.2.Based on the results,it can be suggested that the adjustment factor of 0.2 is also applicable to Malaysian hardwood timbers with a characteristic density above 700 kg/m^(3). 展开更多
关键词 Depth adjustment factor Malaysian hardwood timber bending strength Eurocode 5
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In Situ Generation of Copper Nanoparticles in Heat-Treated Copper-Containing Masson’s Pine as a Preservative Process for Sawn Timber
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作者 Minting Lai Guijun Xie +2 位作者 Wanju Li Lamei Li Yongjian Cao 《Journal of Renewable Materials》 SCIE EI 2023年第6期2665-2678,共14页
Heat-treated wood has good dimensional stability,durability,and color,but its susceptibility to fungal growth affects its commercial value.In this study,lumber harvested from mature Masson’s pine(Pinus massoniana Lam... Heat-treated wood has good dimensional stability,durability,and color,but its susceptibility to fungal growth affects its commercial value.In this study,lumber harvested from mature Masson’s pine(Pinus massoniana Lamb.)was vacuum impregnated with a basic copper salt solution(copper hydroxide,diethanolamine,and polyethylene glycol 200)prior to heat-treatment at 220℃ for 3 h.Antifungal properties,surface chemistry,crystal structure and sugar contents were tested,compared with heat treatment alone.The results showed that the samples treated by heating without copper salt treatment showed poor suppression of fungal growth,the copperimpregnated heat-treated wood suppressed(100%)the growth of Botryodiplodia theobromae Pat.,Aspergillus niger V.Tiegh.,Penicillium citrinum Thom,and Trichoderma viride Pers.The combined results of X-ray photoelectron spectroscopy,X-ray diffraction and sugars analysis suggested that fungal inhibition by the heat-treated copper-bearing Masson’s pine was mainly due to the reduction of the metal salt by PEG200 at high temperature to generate copper nanoparticles.In addition,the reduced sugar content of the treated timber,and hence the nutrient substrate for spoilage microbes,reduced in the presence of the metal salts at high-temperature.This study has demonstrated an effective method of increasing low-grade wood’s utility and commercial value. 展开更多
关键词 Heat treatment Masson’s pine sawn timber inhibition of fungal growth copper nanoparticles
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Three-dimensional inversion of knot defects recognition in timber cutting
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作者 Yizhuo Zhang Dapeng Jiang +1 位作者 Zebing Zhang Jinhao Chen 《Journal of Forestry Research》 SCIE CAS CSCD 2023年第4期1145-1152,共8页
The comprehensive utilization of wood is the main goal of log cutting,but knot defects increase the diffi-culty of rationally optimizing cutting.Due to the lack of real shape data of knot defects in logs,it is diffi c... The comprehensive utilization of wood is the main goal of log cutting,but knot defects increase the diffi-culty of rationally optimizing cutting.Due to the lack of real shape data of knot defects in logs,it is diffi cult for detection methods to establish a correlation between signal and defect morphology.An image-processing method is proposed for knot inversion based on distance regularized level set segmentation(DRLSE)and spatial vertex clustering,and with the inversion of the defects existing relative board position in the log,an inversion model of the knot defect is established.First,the defect edges of the top and bottom images of the boards are extracted by DRLSE and ellipse fi tting,and the major axes of the ellipses made coplanar by angle correction;second,the coordinate points of the top and bottom ellipse edges are extracted to form a spatial straight line;third,to solve the intersection dispersion of spatial straight lines and the major axis plane,K-medoids clustering is used to locate the vertex.Finally,with the vertex and the large ellipse,a 3D cone model is constructed which can be used to invert the shape of knots in the board.The experiment was conducted on ten defective larch boards,and the experimental results showed that this method can accurately invert the shapes of defects in solid wood boards with the advantages of low cost and easy operation. 展开更多
关键词 timber knot inversion Distance regularized level set segmentation(DRLSE) Ellipse fi tting K-medoids cluster
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古建筑木构件开裂机制、评估与加固研究进展 被引量:3
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作者 周海宾 韩旭 +2 位作者 黄磊 王卫滨 王双永 《木材科学与技术》 北大核心 2024年第1期13-22,共10页
开裂作为古建筑木构件最常见的残损类型之一,影响木构件的长期服役性能,是古建筑稳定性与安全性评估的重要考查内容。本文从古建筑木构件开裂情况、原因、影响,评估方法及修复加固等方面,系统梳理古建筑木构件开裂残损相关研究成果。分... 开裂作为古建筑木构件最常见的残损类型之一,影响木构件的长期服役性能,是古建筑稳定性与安全性评估的重要考查内容。本文从古建筑木构件开裂情况、原因、影响,评估方法及修复加固等方面,系统梳理古建筑木构件开裂残损相关研究成果。分析发现我国古建筑木构件开裂的主要原因为木材干缩与受力破坏,主要类型为纵向开裂,开裂可降低木构件力学性能,也可为其他不利因素作用于木构件提供条件。目前主要通过实际试验与数值模拟评估开裂对木构件性能的影响,利用金属材料、纤维增强复合材料(fiber reinforced polymer,FRP)与高分子树脂材料对开裂木构件进行修复加固。然而,由于古建筑的特殊性与木材变异性,仍需进一步探索木构件的不同尺度开裂机制,开发适用于古建筑开裂木构件的检测、评估与加固方法,建立科学系统性的古建筑保护体系。 展开更多
关键词 古建筑木构件 木材开裂机制 修复加固
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Novel Proposal of Bio-based Sewing Timber Joint:Learning from Diatoms
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作者 Mauricio Díaz Valdés Melisa Gálvez Bohórquez 《Journal of Building Material Science》 2023年第1期1-8,共8页
The twenty-first century is one of the most complex in the history of humanity,mainly due to the ecological crisis it is going through.The construction sector generates about 40%of CO2 emissions into the environment;t... The twenty-first century is one of the most complex in the history of humanity,mainly due to the ecological crisis it is going through.The construction sector generates about 40%of CO2 emissions into the environment;the foregoing should motivate this sector to seek new alternatives to develop new building practices.Taking these current needs into account,this document classifies and presents a multidisciplinary solution that integrates biology,engineering and architecture to develop a new and innovative lightweight timber structure;it divides with a main structure made of timber and an innovative joint system made of bio-polymers connecting all the panels.Through the study of diatoms,it was able to analyze the bio-morphology of the structure,joints and in particular the geometry since they were the inspiration for the design of this structure that presents an innovative and novel design of structural optimization.Through parametric design and digital fabrication,it was able to create a complex geometry that obtains excellent structural behavior.This research discusses and explores how materials,geometry led to the optimization of a structure and how new structures can arise,thanks to biology new solutions can be obtained that are completely sustainable,being a clear example of how to combat the effects of the climate change and in a precise way it highlights the advantages of the bio-design in the architectural design. 展开更多
关键词 DIATOMS timber joinery Computational method Topology optimization Biomimetics BIO-INSPIRED Lightweight structure
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出踩与面宽方向柱头科斗栱抗震性能对比试验及数值分析 被引量:4
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作者 薛建阳 宋德军 +1 位作者 吴晨伟 张栋 《土木工程学报》 EI CSCD 北大核心 2024年第2期11-24,共14页
为研究加载方向对斗栱抗震性能的影响,文章基于地震作用的随机性和斗栱出踩与面宽方向的构造差异,对2个足尺柱头科斗栱分别沿出踩和面宽方向进行拟静力试验,得到斗栱的破坏模式、承载力、刚度与强度退化、耗能和变形能力。结果表明:斗... 为研究加载方向对斗栱抗震性能的影响,文章基于地震作用的随机性和斗栱出踩与面宽方向的构造差异,对2个足尺柱头科斗栱分别沿出踩和面宽方向进行拟静力试验,得到斗栱的破坏模式、承载力、刚度与强度退化、耗能和变形能力。结果表明:斗栱在出踩和面宽方向分别加载时,大斗均相对平板枋滑移,馒头榫挤压剪断。出踩方向受力时单昂与桃尖梁相对滑移,面宽方向受力时整体明显转动。相比面宽方向受力的斗栱,出踩方向受力的斗栱具有更高的承载力、初始刚度和耗能能力,而变形能力较差。文章开展柱头科斗栱的数值分析,模拟结果与试验结果吻合较好,研究出踩和面宽不同加载方向、轴压荷载、木构件之间摩擦系数和木材弹性模量对其抗震性能的影响。结果表明:面宽方向是柱头科斗栱的最不利受力方向,其正负向承载力比出踩方向分别低19.21%和17.03%;轴压荷载和木构件之间摩擦系数越大,斗栱承载力越大,而木材顺纹弹性模量和横纹径向弹性模量对斗栱的初始刚度和承载力影响较小。 展开更多
关键词 古建筑木结构 柱头科斗栱 水平加载方向 抗震性能 数值分析
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高温预处理对杨木正交胶合木剪力墙抗侧力性能的影响 被引量:1
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作者 岳孔 李响 +5 位作者 石鑫磊 焦学凯 吴鹏 张仲凤 董国良 方远进 《林业科学》 EI CAS CSCD 北大核心 2024年第7期117-128,共12页
[目的]研究往复荷载作用时国产速生杨木正交胶合木(CLT)剪力墙的抗侧力性能,阐明木材高温预处理和加速老化对剪力墙抗侧力性能的影响,为高温改性技术和国产速生木材在建筑结构中的高效利用提供参考。[方法]以木结构建筑常用的进口欧洲... [目的]研究往复荷载作用时国产速生杨木正交胶合木(CLT)剪力墙的抗侧力性能,阐明木材高温预处理和加速老化对剪力墙抗侧力性能的影响,为高温改性技术和国产速生木材在建筑结构中的高效利用提供参考。[方法]以木结构建筑常用的进口欧洲云杉规格材为对照,以相同强度等级的国产速生杨木为研究对象,选用180℃为预处理温度对杨木进行高温改性,制备5面全尺寸正交胶合木剪力墙,开展往复荷载作用时加速老化前后正交胶合木剪力墙的抗侧力性能试验。[结果]与相同层板强度等级的欧洲云杉正交胶合木剪力墙相比,往复荷载作用时未处理杨木正交胶合木剪力墙的极限承载力、弹性抗侧刚度、耗能能力分别降低5.8%、12.9%、8.0%;木材经高温预处理、墙体经加速老化或二者联合处理后,杨木正交胶合木剪力墙的抗侧力性能指标不同程度降低;与未处理杨木正交胶合木墙体相比,加速老化处理后,墙体的极限承载力、弹性抗侧刚度、耗能能力分别降低9.4%、9.7%、11.2%;木材经高温预处理后,经加速老化,墙体的极限承载力、弹性抗侧刚度、耗能能力变化较小,分别降低2.9%、2.4%、5.0%。[结论]往复荷载作用时,国产速生杨木正交胶合木剪力墙的抗侧力性能略低于相同层板强度等级的欧洲云杉正交胶合木剪力墙,水平力作用时二者具有相似破坏模式,均为抗拔连接件节点处钉子被剪断;木材经高温预处理、墙体经加速老化或二者联合处理后,杨木正交胶合木剪力墙的破坏模式均为底部墙角抗拔连接件处木材被拉断或劈裂破坏;木材高温预处理能够有效降低加速老化对剪力墙抗侧力性能的影响,具有相对较好的抗老化能力;建立正交胶合木剪力墙极限承载力计算模型,理论值与试验值误差小于10%。 展开更多
关键词 速生杨木 正交胶合木剪力墙 抗侧力性能 高温预处理 加速老化
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高立地指数下杉木生长量及材种结构的立地及密度效应
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作者 陈琴 谢树 +5 位作者 段爱国 陈仕昌 韦家国 罗星乐 莫运勇 黄开勇 《林业科学研究》 CSCD 北大核心 2024年第4期1-11,共11页
[目的]探讨立地质量和林分密度对杉木人工林生长量及材种结构的影响,为杉木大径材培育提供理论依据。[方法]以林龄28~36年生的杉木人工林为研究对象,按上、中、下不同坡位以及不同坡向设置63块标准样地,调查林分生长量及林分基本情况,... [目的]探讨立地质量和林分密度对杉木人工林生长量及材种结构的影响,为杉木大径材培育提供理论依据。[方法]以林龄28~36年生的杉木人工林为研究对象,按上、中、下不同坡位以及不同坡向设置63块标准样地,调查林分生长量及林分基本情况,通过相关性分析和回归拟合分析进行数据处理和分析。[结果]当林分密度相近时,立地指数越高,培育相同年限所获得的单株材积、蓄积量和大径材出材率越高;同一立地条件下,在一定的密度范围内林分树高、胸径、单株材积和大径材出材率随密度增加而减小,蓄积量随密度增加而增大;立地指数相同时,密度对胸径生长分化的影响大于树高,立地指数不同时林分密度对树高和胸径生长分化的影响程度也不同。[结论]在立地指数达22及以上的立地条件下培育杉木大径材,可通过3次间伐进行密度控制,林分最终保留密度宜为650~1000株·hm^(−2)。 展开更多
关键词 大径材培育 杉木 生长量 材种结构 出材率
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木框架-正交胶合木剪力墙多层结构体系关键节点力学性能试验与数值模拟
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作者 李征 王子为 +2 位作者 何敏娟 韩倩文 刘青 《土木工程学报》 EI CSCD 北大核心 2024年第11期1-13,共13页
胶合木(Glulam)框架结构能提供开阔的使用空间,正交胶合木(Cross Laminated Timber,CLT)剪力墙结构能提供较大的抗侧刚度,文章提出了一种二者相结合的结构体系,并针对体系中的2类关键节点开展研究,即CLT剪力墙-CLT楼板节点(简称剪力墙-... 胶合木(Glulam)框架结构能提供开阔的使用空间,正交胶合木(Cross Laminated Timber,CLT)剪力墙结构能提供较大的抗侧刚度,文章提出了一种二者相结合的结构体系,并针对体系中的2类关键节点开展研究,即CLT剪力墙-CLT楼板节点(简称剪力墙-楼板节点)和CLT剪力墙-胶合木梁节点(简称剪力墙-梁节点)。开展的主要工作如下:(1)自攻螺钉抗剪与抗拔试验;(2)剪力墙-楼板节点的抗剪与抗拔试验;(3)剪力墙-梁节点的弯剪复合试验。试验结果显示:自攻螺钉抗剪荷载-位移曲线有明显的弹性段和塑性段,而抗拔延性稍差。剪力墙-楼板节点抗剪试件的典型破坏模式为钉拔剪与木材劈裂破坏,其承载力达峰后会突降;剪力墙-楼板节点抗拔试件的典型破坏模式为钉拔出与木材承压破坏,其初始刚度较高、延性较好。剪力墙-梁节点抗弯剪试件的典型破坏模式为钉拔出破坏,节点有较好的延性,但滞回曲线捏缩效应明显。根据试验结果,文章对自攻螺钉、剪力墙-楼板节点、剪力墙-梁节点的力学指标进行了计算,其中,剪力墙-楼板节点试件的抗剪、抗拔承载力分别为26.66kN、21.50kN;剪力墙-梁节点试件的承载力、弹性刚度和延性系数均值分别为10.89kN·m、459.40kN·m/rad和3.68。最后,文章对这2类关键节点进行了数值模拟,数值模拟结果与试验结果吻合较好。文章针对胶合木框架-正交胶合木剪力墙结构的关键节点开展试验及数值模拟研究,以期为该类结构的工程应用提供理论与技术支撑。 展开更多
关键词 正交胶合木 胶合木框架 连接节点 拟静力试验 数值模拟
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