Pub Date : 2024-01-02DOI: 10.1186/s10086-023-02115-z
Layth S. Al-Rukaibawi, Mansour Kachichian, György Károlyi
This research used the new ISO 23478-2022 standard as a reference for the calculation of mechanical properties of N-finity, and to understand the failure modes in compression. Previous studies have investigated the mechanical properties of laminated bamboo lumber (LBL), however no study has evaluated the mechanical properties of LBL according to the recently published ISO 23478-2022. The compression testing programme in parallel and perpendicular-to-grain directions were conducted. The measured elastic stiffness properties and compressive strengths show anisotropy with higher compressive strength and stiffness parallel-to-grain direction as compared to those at the transversal directions. The observed failure modes at the parallel-to-grain direction exhibited a mixed mode failure, whereas perpendicular-to-grain directions exhibited failure with longitudinal splitting with crack propagation rupture. This finding can be quantified using Hills failure criterion principle to define the failure criterion and to estimate the Hill’s yield failure ratios.
这项研究以新的 ISO 23478-2022 标准为参考，计算了 N-finity 的力学性能，并了解了压缩失效模式。以前的研究曾对层压竹材（LBL）的机械性能进行过调查，但还没有研究根据最近发布的 ISO 23478-2022 标准对层压竹材的机械性能进行过评估。研究人员进行了平行和垂直于纹理方向的压缩测试。测得的弹性刚度特性和抗压强度显示出各向异性，与横向相比，平行于纹理方向的抗压强度和刚度更高。在平行于纹理方向观察到的破坏模式表现为混合模式破坏，而垂直于纹理方向则表现为纵向劈裂和裂纹扩展破坏。这一发现可利用希尔失效准则原理进行量化，以确定失效准则并估算希尔屈服失效比。
{"title":"Mechanical properties of laminated bamboo lumber N-finity according to ISO 23478-2022","authors":"Layth S. Al-Rukaibawi, Mansour Kachichian, György Károlyi","doi":"10.1186/s10086-023-02115-z","DOIUrl":"https://doi.org/10.1186/s10086-023-02115-z","url":null,"abstract":"This research used the new ISO 23478-2022 standard as a reference for the calculation of mechanical properties of N-finity, and to understand the failure modes in compression. Previous studies have investigated the mechanical properties of laminated bamboo lumber (LBL), however no study has evaluated the mechanical properties of LBL according to the recently published ISO 23478-2022. The compression testing programme in parallel and perpendicular-to-grain directions were conducted. The measured elastic stiffness properties and compressive strengths show anisotropy with higher compressive strength and stiffness parallel-to-grain direction as compared to those at the transversal directions. The observed failure modes at the parallel-to-grain direction exhibited a mixed mode failure, whereas perpendicular-to-grain directions exhibited failure with longitudinal splitting with crack propagation rupture. This finding can be quantified using Hills failure criterion principle to define the failure criterion and to estimate the Hill’s yield failure ratios.","PeriodicalId":17664,"journal":{"name":"Journal of Wood Science","volume":"72 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139084280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The method used to cultivate the popular Japanese mushroom Grifola frondosa (maitake), called 'wood log cultivation', comprised two steps: (1) the mycelium is grown around a wood log in a plastic bag, and (2) the mycelium that has spread on the wood log is transferred into casing substrates in a forest. This method is still popular in Japan due to its low cost and high-quality crop production. The importance of the microbiome that inhabits mushroom-cultivation surroundings has recently attracted attention, but no study of the microbial communities in maitake cultivation has been published. We investigated how the bacterial communities changed in wood logs in comparison with a control group (without inoculation) and their interaction with maitake during the first to fourth years of maitake wood log cultivation. A maitake biomass was detected by quantitative PCR in wood logs but not in the casings, and we thus decided to investigate the bacterial communities in wood log samples for control and first- to fourth-year cultivation. The results indicate that the phyla Proteobacteria, Firmicutes, and Gemmatimonadota play key roles in changes of the microbiome composition for maitake wood log cultivation. In a functional profile, bacteria communities in the wood logs during maitake cultivation showed higher relative abundance in cellulolysis, glycolysis, TCA cycle, and many biosynthesis pathways, whereas the control group showed higher relative abundance in fermentation. These results suggested that (i) the bacterial communities which inhabited maitake cultivated wood logs may help the maitake degrade wood cellulose, and (ii) part of the glucose from the cellulose degraded by both maitake and bacteria was used for the bacterial TCA cycle instead of fermentation. Bacteria also produce some chemicals that maitake mycelium may need. It is also likely that some potential intracellular parasites dwell with maitake. The different cultivation stages showed different network structures. A network analysis indicated that Class Gammaproteobacteria is a potential keystone taxon for the microbiome network stability of maitake cultivated wood logs. These results contribute to the understanding of the microbiome in maitake-cultivation surroundings and will improve maitake wood log cultivation.
{"title":"Characterization of microbial communities during Grifola frondosa (maitake) wood log cultivation","authors":"Fu-Chia Chen, Taichi Motoda, Ichiro Kamei, Yoshio Kijidani","doi":"10.1186/s10086-023-02111-3","DOIUrl":"https://doi.org/10.1186/s10086-023-02111-3","url":null,"abstract":"The method used to cultivate the popular Japanese mushroom Grifola frondosa (maitake), called 'wood log cultivation', comprised two steps: (1) the mycelium is grown around a wood log in a plastic bag, and (2) the mycelium that has spread on the wood log is transferred into casing substrates in a forest. This method is still popular in Japan due to its low cost and high-quality crop production. The importance of the microbiome that inhabits mushroom-cultivation surroundings has recently attracted attention, but no study of the microbial communities in maitake cultivation has been published. We investigated how the bacterial communities changed in wood logs in comparison with a control group (without inoculation) and their interaction with maitake during the first to fourth years of maitake wood log cultivation. A maitake biomass was detected by quantitative PCR in wood logs but not in the casings, and we thus decided to investigate the bacterial communities in wood log samples for control and first- to fourth-year cultivation. The results indicate that the phyla Proteobacteria, Firmicutes, and Gemmatimonadota play key roles in changes of the microbiome composition for maitake wood log cultivation. In a functional profile, bacteria communities in the wood logs during maitake cultivation showed higher relative abundance in cellulolysis, glycolysis, TCA cycle, and many biosynthesis pathways, whereas the control group showed higher relative abundance in fermentation. These results suggested that (i) the bacterial communities which inhabited maitake cultivated wood logs may help the maitake degrade wood cellulose, and (ii) part of the glucose from the cellulose degraded by both maitake and bacteria was used for the bacterial TCA cycle instead of fermentation. Bacteria also produce some chemicals that maitake mycelium may need. It is also likely that some potential intracellular parasites dwell with maitake. The different cultivation stages showed different network structures. A network analysis indicated that Class Gammaproteobacteria is a potential keystone taxon for the microbiome network stability of maitake cultivated wood logs. These results contribute to the understanding of the microbiome in maitake-cultivation surroundings and will improve maitake wood log cultivation.","PeriodicalId":17664,"journal":{"name":"Journal of Wood Science","volume":"4 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2023-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138563139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study confirmed that the loss tangent (or tangent loss, tan δ) obtained from the longitudinal vibration of a wood log increases with the apparent density difference between sapwood and heartwood, owing to moisture content difference. The reason for this was estimated to be the shear stress occurring when the longitudinal vibration is excited from the calculation of the longitudinal vibration equation for a cylindrical model with different sapwood and heartwood densities. According to the measurement of the vibrational properties of 35 sugi (Cryptomeria japonica) logs with large moisture content variation in the sapwood and heartwood, the tan δ for longitudinal vibration increased compared with that for flexural vibration when the apparent sapwood density exceeded apparent heartwood density, whereas the difference in the specific dynamic Young’s modulus (E/ρ) was small. To discover why tan δ increases, both the axial and shear strain energy were calculated from the numerical solution of the longitudinal vibration of a cylindrical model by only considering the apparent density difference between sapwood and heartwood. It was found that the shear strain energy increases with the apparent density difference. Because it is known from previous studies that tan δ from the shear strain (tan δS) is larger than that from the axial strain (tan δA), this study concluded that tan δ increases with the apparent density difference. The ratio of increase of tan δ calculated by the model adequately explaange of the measured tan δ caused by the longitudinal vibration of a sugi log.
这项研究证实，由于含水率不同，从原木纵向振动中获得的损耗切线（或切线损耗，tan δ）会随着边材和心材表观密度的不同而增加。根据对边材和心材密度不同的圆柱形模型的纵向振动方程的计算，估计其原因是激发纵向振动时产生的剪应力。根据对 35 根边材和心材含水率差异较大的杉木（Cryptomeria japonica）原木振动特性的测量，当表观边材密度超过表观心材密度时，纵向振动的 tan δ 比弯曲振动的 tan δ 增加，而比动态杨氏模量（E/ρ）的差异很小。为了探究 tan δ 增大的原因，我们只考虑了边材和心材的表观密度差，通过对圆柱模型纵向振动的数值求解计算出了轴向应变能和剪切应变能。结果发现，剪切应变能随着表观密度差的增加而增加。根据以往的研究可知，剪切应变（tan δS）产生的 tan δ 要大于轴向应变（tan δA）产生的 tan δ，因此本研究认为 tan δ 会随着表观密度差的增大而增大。该模型计算出的 tan δ 的增大比充分解释了杉木纵向振动引起的 tan δ 的测量值。
{"title":"Evaluation of increase in loss tangent from longitudinal vibration of wood log by considering apparent density difference between sapwood and heartwood caused by moisture content","authors":"Toshiyuki Fukui, Yoshiyuki Yanase, Yoshihisa Fujii","doi":"10.1186/s10086-023-02114-0","DOIUrl":"https://doi.org/10.1186/s10086-023-02114-0","url":null,"abstract":"This study confirmed that the loss tangent (or tangent loss, tan δ) obtained from the longitudinal vibration of a wood log increases with the apparent density difference between sapwood and heartwood, owing to moisture content difference. The reason for this was estimated to be the shear stress occurring when the longitudinal vibration is excited from the calculation of the longitudinal vibration equation for a cylindrical model with different sapwood and heartwood densities. According to the measurement of the vibrational properties of 35 sugi (Cryptomeria japonica) logs with large moisture content variation in the sapwood and heartwood, the tan δ for longitudinal vibration increased compared with that for flexural vibration when the apparent sapwood density exceeded apparent heartwood density, whereas the difference in the specific dynamic Young’s modulus (E/ρ) was small. To discover why tan δ increases, both the axial and shear strain energy were calculated from the numerical solution of the longitudinal vibration of a cylindrical model by only considering the apparent density difference between sapwood and heartwood. It was found that the shear strain energy increases with the apparent density difference. Because it is known from previous studies that tan δ from the shear strain (tan δS) is larger than that from the axial strain (tan δA), this study concluded that tan δ increases with the apparent density difference. The ratio of increase of tan δ calculated by the model adequately explaange of the measured tan δ caused by the longitudinal vibration of a sugi log.","PeriodicalId":17664,"journal":{"name":"Journal of Wood Science","volume":"108 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2023-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138555212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-03DOI: 10.1186/s10086-023-02112-2
Hiroaki Horiyama, Keisuke Kojiro, Yuzo Furuta
Dynamic mechanical analysis (DMA) measurements of water-saturated radiata pine wood in the temperature range from 0 ℃ to 100 ℃ were focused to clarify the transition in viscoelastic properties within successive annual rings. Four radially consecutive specimens were taken per annual ring and DMA measurements in the tangential direction were performed using these specimens. The following results were obtained. The peak of tanδ caused by micro-Brownian motion of lignin was observed in all samples. The temperature of peak tanδ tended to decrease from earlywood to latewood within an annual ring. The temperature of peak tanδ increased across annual ring boundary. The same trend was repeated within the next annual ring. It was found that the viscoelastic properties transitioned within successive annual rings.
{"title":"Transition in viscoelastic properties within successive annual rings of radiata pine (Pinus radiata)","authors":"Hiroaki Horiyama, Keisuke Kojiro, Yuzo Furuta","doi":"10.1186/s10086-023-02112-2","DOIUrl":"https://doi.org/10.1186/s10086-023-02112-2","url":null,"abstract":"Dynamic mechanical analysis (DMA) measurements of water-saturated radiata pine wood in the temperature range from 0 ℃ to 100 ℃ were focused to clarify the transition in viscoelastic properties within successive annual rings. Four radially consecutive specimens were taken per annual ring and DMA measurements in the tangential direction were performed using these specimens. The following results were obtained. The peak of tanδ caused by micro-Brownian motion of lignin was observed in all samples. The temperature of peak tanδ tended to decrease from earlywood to latewood within an annual ring. The temperature of peak tanδ increased across annual ring boundary. The same trend was repeated within the next annual ring. It was found that the viscoelastic properties transitioned within successive annual rings.","PeriodicalId":17664,"journal":{"name":"Journal of Wood Science","volume":"32 4","pages":""},"PeriodicalIF":2.9,"publicationDate":"2023-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138510081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-27DOI: 10.1186/s10086-023-02113-1
Ryutaro Sudo, Kenji Aoki
Although embedment properties are vital to timber engineering, the behavior and strain distributions in wood-based panels have not been clarified in detail. Our early studies suggested four possible causes of failure behavior and strain distribution: (i) two types of failure behavior (in-plane and out-of-plane failure); (ii) enlargement of the stress-spreading range with increasing load step; (iii) reduction of the stress-spreading range (normalized by dowel diameter) with increasing dowel diameter; and (iv) preferential stress spreading in the vertical and horizontal directions along the strong and weak-axis specifications, respectively. However, these hypotheses were not supported by actual observations. The present study aims to observe and clarify the surface strain distribution via digital image correlation and the internal failure behavior via computed tomography scanning. Most results of the wood-based panel specimens (plywood and oriented strand board) did not contradict the above hypotheses. The failure behaviors of plywood and oriented strand board are likely determined by the direction of the veneer fibers and the layer’s position, respectively. Within the strong axial layer of plywood, fibers on both sides of the dowel were densified by fibers dissociated immediately above the dowel, whereas the weak axial layer in plywood was deformed like a timber under partial compression perpendicular to the grain. In contrast, oriented strand board under an embedding stress exhibited a circularly distributed strain and a dispersed void area in its outer layer. Densification was observed only in the inner layer.
{"title":"Investigation of mechanical properties and elucidation of factors affecting wood-based structural panels under embedment stress with a circular dowel II: detailed observation for plywood and OSB using DIC and CT scanning","authors":"Ryutaro Sudo, Kenji Aoki","doi":"10.1186/s10086-023-02113-1","DOIUrl":"https://doi.org/10.1186/s10086-023-02113-1","url":null,"abstract":"Although embedment properties are vital to timber engineering, the behavior and strain distributions in wood-based panels have not been clarified in detail. Our early studies suggested four possible causes of failure behavior and strain distribution: (i) two types of failure behavior (in-plane and out-of-plane failure); (ii) enlargement of the stress-spreading range with increasing load step; (iii) reduction of the stress-spreading range (normalized by dowel diameter) with increasing dowel diameter; and (iv) preferential stress spreading in the vertical and horizontal directions along the strong and weak-axis specifications, respectively. However, these hypotheses were not supported by actual observations. The present study aims to observe and clarify the surface strain distribution via digital image correlation and the internal failure behavior via computed tomography scanning. Most results of the wood-based panel specimens (plywood and oriented strand board) did not contradict the above hypotheses. The failure behaviors of plywood and oriented strand board are likely determined by the direction of the veneer fibers and the layer’s position, respectively. Within the strong axial layer of plywood, fibers on both sides of the dowel were densified by fibers dissociated immediately above the dowel, whereas the weak axial layer in plywood was deformed like a timber under partial compression perpendicular to the grain. In contrast, oriented strand board under an embedding stress exhibited a circularly distributed strain and a dispersed void area in its outer layer. Densification was observed only in the inner layer.","PeriodicalId":17664,"journal":{"name":"Journal of Wood Science","volume":"12 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2023-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138543049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In this work, a new type of structural sandwich panels made with laminated oil palm wood core and rubberwood-based oriented strand board (OSB)/plywood faces were introduced for energy-efficient wall applications in Thailand. Effect of the manufacturing process and material parameters including adhesive content (250 g/m 2 and 500 g/m 2 ), core configuration (cross or parallel laminated oil palm lumber) and density (low and medium) and face material type (rubberwood-based OSB/plywood) on panel’s properties were explored. The panels were produced using two-component polyurethane adhesive and a constant clamping pressure of 0.6 MPa. Adhesive content of 250 g/m 2 was found to be sufficient for gluing all layers, with wood failure percentage of more than 80% as required by the standard. In-plane dimensional stability of the panels was mainly affected by the core configuration; it was better for cross laminated oil palm wood core sandwich panel. Higher core density resulted in increased density, thermal conductivity and compressive strength in the major direction but lower thermal resistance of the panel. The plywood face sandwich panels provided slightly higher compressive strength than OSB face sandwich panel, and their failure mechanisms were also different. The heat loss of these panels was about one-third of concrete and brick walls, hence, they can provide better insulation for indoor space. Based on the measured thermal conductivity, it was expected that these panels would pass the energy criteria according to Building Energy Code of Thailand. Thus, from the energy saving and sustainability perspectives, these panels can potentially be used as energy efficient wall panels for buildings, not only for Thailand but also for other tropical countries, where the oil palm wood and rubberwood resource is available.
{"title":"Developing structural sandwich panels for energy-efficient wall applications using laminated oil palm wood and rubberwood-based plywood/oriented strand board","authors":"Sataporn Jantawee, Hyungsuk Lim, Minghao Li, Jung-Kwon Oh, Zoltan Pasztory, Heejin Cho, Suthon Srivaro","doi":"10.1186/s10086-023-02109-x","DOIUrl":"https://doi.org/10.1186/s10086-023-02109-x","url":null,"abstract":"Abstract In this work, a new type of structural sandwich panels made with laminated oil palm wood core and rubberwood-based oriented strand board (OSB)/plywood faces were introduced for energy-efficient wall applications in Thailand. Effect of the manufacturing process and material parameters including adhesive content (250 g/m 2 and 500 g/m 2 ), core configuration (cross or parallel laminated oil palm lumber) and density (low and medium) and face material type (rubberwood-based OSB/plywood) on panel’s properties were explored. The panels were produced using two-component polyurethane adhesive and a constant clamping pressure of 0.6 MPa. Adhesive content of 250 g/m 2 was found to be sufficient for gluing all layers, with wood failure percentage of more than 80% as required by the standard. In-plane dimensional stability of the panels was mainly affected by the core configuration; it was better for cross laminated oil palm wood core sandwich panel. Higher core density resulted in increased density, thermal conductivity and compressive strength in the major direction but lower thermal resistance of the panel. The plywood face sandwich panels provided slightly higher compressive strength than OSB face sandwich panel, and their failure mechanisms were also different. The heat loss of these panels was about one-third of concrete and brick walls, hence, they can provide better insulation for indoor space. Based on the measured thermal conductivity, it was expected that these panels would pass the energy criteria according to Building Energy Code of Thailand. Thus, from the energy saving and sustainability perspectives, these panels can potentially be used as energy efficient wall panels for buildings, not only for Thailand but also for other tropical countries, where the oil palm wood and rubberwood resource is available.","PeriodicalId":17664,"journal":{"name":"Journal of Wood Science","volume":" 1280","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135186710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-17DOI: 10.1186/s10086-023-02108-y
Katarzyna Kurkowiak, Lukas Emmerich, Holger Militz
Abstract This study aimed to investigate the relationship between moisture dynamics of sorbitol and citric acid (SorCA) modified wood and its biological durability. Specifically, the research aimed to determine the chemical loading needed for effective protection against wood-destroying basidiomycetes, while also improving the understanding of the moisture behavior of SorCA-modified wood. The SorCA modification process is relatively new, and thus, there is limited knowledge on its moisture behavior and its impact on biological durability. The research focused on Scots pine sapwood ( Pinus sylvestris L.) and used the EN 113-2 standard to investigate its durability against wood-destroying basidiomycetes. Moisture behavior was analyzed through short-term water uptake and release tests, capillary water uptake and CEN/TS 16818. Results showed a significant reduction in liquid and water vapor uptake, likely due to a reduction in the maximum moisture capacity within the wood cell wall. The study confirmed that high chemical loadings (i.e., weight percent gain, WPG) are necessary for adequate decay protection.
{"title":"Biological durability and wood–water interactions of sorbitol and citric acid (SorCA) modified wood","authors":"Katarzyna Kurkowiak, Lukas Emmerich, Holger Militz","doi":"10.1186/s10086-023-02108-y","DOIUrl":"https://doi.org/10.1186/s10086-023-02108-y","url":null,"abstract":"Abstract This study aimed to investigate the relationship between moisture dynamics of sorbitol and citric acid (SorCA) modified wood and its biological durability. Specifically, the research aimed to determine the chemical loading needed for effective protection against wood-destroying basidiomycetes, while also improving the understanding of the moisture behavior of SorCA-modified wood. The SorCA modification process is relatively new, and thus, there is limited knowledge on its moisture behavior and its impact on biological durability. The research focused on Scots pine sapwood ( Pinus sylvestris L.) and used the EN 113-2 standard to investigate its durability against wood-destroying basidiomycetes. Moisture behavior was analyzed through short-term water uptake and release tests, capillary water uptake and CEN/TS 16818. Results showed a significant reduction in liquid and water vapor uptake, likely due to a reduction in the maximum moisture capacity within the wood cell wall. The study confirmed that high chemical loadings (i.e., weight percent gain, WPG) are necessary for adequate decay protection.","PeriodicalId":17664,"journal":{"name":"Journal of Wood Science","volume":"78 6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135995962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Cross-laminated timber (CLT) is a promising construction material. When CLT is used for horizontal applications, shear stress occurs in the out-of-plane direction and can fracture the transverse layers owing to the rolling shear. The out-of-plane shear strength of the CLT can be evaluated by an out-of-plane loading test and is affected by the CLT layups and/or span conditions. In this study, we conducted out-of-plane loading tests on 3-layer 4-ply, 5-layer 7-ply, 7-layer 7-ply, and 9-layer 9-ply CLT made of Japanese larch ( Larix kaempferi ) under various spans and investigated the effect of layups and spans on the out-of-shear strength. The fracture modes of the specimens were classified into three types: shear fracture, shear fracture accompanied by bending fracture, and bending fracture. The out-of-plane shear strength of the specimens except for the 9-layer 9-ply ones decreased as the span increased, and then converged to a constant value (1.0–1.5 kN/mm 2 ). In addition, the shear strength decreased exponentially as the number of laminae in the transverse layers increased and then converged to a constant value (1.0–1.5 kN/mm 2 ). The out-of-plane shear strength of the 9-layer 9-ply specimens decreased as the shear span increased; however, the converged value with a longer span could not be calculated because the tests were conducted under only three-span conditions. The shear strength of 3-layer 4-ply specimens was lower than that of the other layups. The results of the Monte Carlo simulation of the shear strength of the laminae in the transverse layers showed that a model, which assumed that the minimum shear strength of the laminae in the transverse layers determined the shear strength of a specimen, tended to correspond with the decreasing tendency of shear strength with longer spans. The results showed that the weakest link model for the out-of-plane shear fracture of the CLT would relate to a specimen with long span.
{"title":"Out-of-plane shear strength of cross-laminated timber made of Japanese Larch (Larix kaempferi) with various layups and spans","authors":"Yasuhiro Kawaai, Ryuya Takanashi, Wataru Ishihara, Yoshinori Ohashi, Kei Sawata, Takanobu Sasaki","doi":"10.1186/s10086-023-02107-z","DOIUrl":"https://doi.org/10.1186/s10086-023-02107-z","url":null,"abstract":"Abstract Cross-laminated timber (CLT) is a promising construction material. When CLT is used for horizontal applications, shear stress occurs in the out-of-plane direction and can fracture the transverse layers owing to the rolling shear. The out-of-plane shear strength of the CLT can be evaluated by an out-of-plane loading test and is affected by the CLT layups and/or span conditions. In this study, we conducted out-of-plane loading tests on 3-layer 4-ply, 5-layer 7-ply, 7-layer 7-ply, and 9-layer 9-ply CLT made of Japanese larch ( Larix kaempferi ) under various spans and investigated the effect of layups and spans on the out-of-shear strength. The fracture modes of the specimens were classified into three types: shear fracture, shear fracture accompanied by bending fracture, and bending fracture. The out-of-plane shear strength of the specimens except for the 9-layer 9-ply ones decreased as the span increased, and then converged to a constant value (1.0–1.5 kN/mm 2 ). In addition, the shear strength decreased exponentially as the number of laminae in the transverse layers increased and then converged to a constant value (1.0–1.5 kN/mm 2 ). The out-of-plane shear strength of the 9-layer 9-ply specimens decreased as the shear span increased; however, the converged value with a longer span could not be calculated because the tests were conducted under only three-span conditions. The shear strength of 3-layer 4-ply specimens was lower than that of the other layups. The results of the Monte Carlo simulation of the shear strength of the laminae in the transverse layers showed that a model, which assumed that the minimum shear strength of the laminae in the transverse layers determined the shear strength of a specimen, tended to correspond with the decreasing tendency of shear strength with longer spans. The results showed that the weakest link model for the out-of-plane shear fracture of the CLT would relate to a specimen with long span.","PeriodicalId":17664,"journal":{"name":"Journal of Wood Science","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135059850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The moisture contents of sugi ( Cryptomeria japonica ), todomatsu ( Abies sachalinensis ) and hinoki ( Chamaecyparis obtusa ) logs were estimated using a method of moisture content estimation proposed in our previous study. In the course of estimation, it was revealed that the regression line of the correlation between specific dynamic Young’s modulus ( E / ρ ) and tangent loss (tan δ ) of green wood was different from that of moisture-conditioned wood and showed species dependency, both of which are not previously reported. Regression lines at the fiber saturation point (FSP) were constructed for each species by measuring E / ρ and tan δ from the flexural vibration of green small specimens and correcting the E / ρ values at their own moisture contents into E / ρ values at the FSP. The correlation of green wood in this study was different from that reported in previous studies of moisture-conditioned wood near the FSP. The correlations of sugi and hinoki were similar, whereas those of sugi and todomatsu were different despite no previous report of species dependency in air-dried wood. The moisture contents 86 logs (not those used to prepare small specimens) were estimated using regression lines of each species. The standard deviation of the difference between the estimated moisture content and the measured moisture content was 15.7%. A systematic error of 25.9% in moisture content was attributed to the different methods of specimen support used for small specimens and logs.
{"title":"Moisture content estimation of green softwood logs of three species based on measurements of flexural vibration","authors":"Toshiyuki Fukui, Yoshiyuki Yanase, Yoshihisa Fujii","doi":"10.1186/s10086-023-02106-0","DOIUrl":"https://doi.org/10.1186/s10086-023-02106-0","url":null,"abstract":"Abstract The moisture contents of sugi ( Cryptomeria japonica ), todomatsu ( Abies sachalinensis ) and hinoki ( Chamaecyparis obtusa ) logs were estimated using a method of moisture content estimation proposed in our previous study. In the course of estimation, it was revealed that the regression line of the correlation between specific dynamic Young’s modulus ( E / ρ ) and tangent loss (tan δ ) of green wood was different from that of moisture-conditioned wood and showed species dependency, both of which are not previously reported. Regression lines at the fiber saturation point (FSP) were constructed for each species by measuring E / ρ and tan δ from the flexural vibration of green small specimens and correcting the E / ρ values at their own moisture contents into E / ρ values at the FSP. The correlation of green wood in this study was different from that reported in previous studies of moisture-conditioned wood near the FSP. The correlations of sugi and hinoki were similar, whereas those of sugi and todomatsu were different despite no previous report of species dependency in air-dried wood. The moisture contents 86 logs (not those used to prepare small specimens) were estimated using regression lines of each species. The standard deviation of the difference between the estimated moisture content and the measured moisture content was 15.7%. A systematic error of 25.9% in moisture content was attributed to the different methods of specimen support used for small specimens and logs.","PeriodicalId":17664,"journal":{"name":"Journal of Wood Science","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134912953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-11DOI: 10.1186/s10086-023-02103-3
Xiaofeng Sun, Minjuan He, Zheng Li
Abstract Cross-laminated timber (CLT) wall panels are commonly connected to the floor or foundation using metal connections, which play a critical role in determining the seismic performance and energy dissipation of the CLT shear walls. In this study, to comprehend the tension–shear coupling effect of the CLT wall-to-floor angle bracket connections under seismic loads, both monotonic and cyclic shear tests were conducted on the angle brackets that were also simultaneously applied with different levels of prescribed vertical axial tension. The influence of the co-existent axial tension on the horizontal shear performance of the angle brackets was analyzed. Furthermore, a numerical model of the angle brackets was developed and validated with the experimental results, which could predict the tension–shear coupling effect based on the monotonic loading scenario. Based on the numerical model, parametric analysis was conducted, and an analytical tension–shear interaction diagram representing the coupling effect of the angle brackets under seismic loads was established. It is found that with an increase of the axial tension from 0 to 30 kN, the shear resisting capacity of the angle brackets is diminished by 33.29%, and the pinching effect of their hysteretic load–displacement curves is mitigated. When the number of the connection-to-floor screws of the angle brackets was increased from 10 to 14, the shear resisting capacity of the angle brackets can be enhanced by 6.43%, and their shear strength degradation can be relieved by 12.85–56.25%. For the CLT wall-to-floor angle brackets, the analytical interaction diagram can be described using one bilinear function, which consists of the ratio between the shear to the shear resistance and the ratio between the tension to the pull-out resistance.
{"title":"An experimental and numerical study on the coupling effect of CLT wall-to-floor angle bracket connections","authors":"Xiaofeng Sun, Minjuan He, Zheng Li","doi":"10.1186/s10086-023-02103-3","DOIUrl":"https://doi.org/10.1186/s10086-023-02103-3","url":null,"abstract":"Abstract Cross-laminated timber (CLT) wall panels are commonly connected to the floor or foundation using metal connections, which play a critical role in determining the seismic performance and energy dissipation of the CLT shear walls. In this study, to comprehend the tension–shear coupling effect of the CLT wall-to-floor angle bracket connections under seismic loads, both monotonic and cyclic shear tests were conducted on the angle brackets that were also simultaneously applied with different levels of prescribed vertical axial tension. The influence of the co-existent axial tension on the horizontal shear performance of the angle brackets was analyzed. Furthermore, a numerical model of the angle brackets was developed and validated with the experimental results, which could predict the tension–shear coupling effect based on the monotonic loading scenario. Based on the numerical model, parametric analysis was conducted, and an analytical tension–shear interaction diagram representing the coupling effect of the angle brackets under seismic loads was established. It is found that with an increase of the axial tension from 0 to 30 kN, the shear resisting capacity of the angle brackets is diminished by 33.29%, and the pinching effect of their hysteretic load–displacement curves is mitigated. When the number of the connection-to-floor screws of the angle brackets was increased from 10 to 14, the shear resisting capacity of the angle brackets can be enhanced by 6.43%, and their shear strength degradation can be relieved by 12.85–56.25%. For the CLT wall-to-floor angle brackets, the analytical interaction diagram can be described using one bilinear function, which consists of the ratio between the shear to the shear resistance and the ratio between the tension to the pull-out resistance.","PeriodicalId":17664,"journal":{"name":"Journal of Wood Science","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135980420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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