In order to investigate the influence of length and compression directions upon behaviour of parallel bamboo strand lumber(PBSL)specimens,240 axial compression tests have been performed.With three similar one differen...In order to investigate the influence of length and compression directions upon behaviour of parallel bamboo strand lumber(PBSL)specimens,240 axial compression tests have been performed.With three similar one different typical failure modes,the mechanical performance for PBSL specimens under compression parallel to grain and perpendicular to grain are different as a whole.From the point of the characteristic values,the compression strength parallel to grain is 2.1 times of the compression strength perpendicular to grain.The elastic modulus for compression parallel to grain is 3.64 times of the compression strength perpendicular to grain.While the compression ratios along two compression directions are equal to each other.The bigger Poisson ratios for one typical side surface is 3.93 times of that for another typical side surface for PBSL specimens under compression perpendicular to grain,and the bigger value is equal to that for PBSL specimens under compression parallel to grain.Length can influence the mechanical properties of the PBSL specimens.The size 50 mm×50 mm×100 mm should be good choice for the standard or code to measure the compression strength.PBSL materials have better ductility under compression parallel to grain than that under compression perpendicular to grain.Stress-strain relationship models were proposed for PBSL specimens under compression parallel to grain and perpendicular to grain,respectively.These proposed models gave a good agreement with the test results.展开更多
Over the past decade,the physical and mechanical performances of laminated bamboo lumber(LBL)–a bamboo-based structural material,have been extensively studied using experimental,analytical,and numerical approaches.Th...Over the past decade,the physical and mechanical performances of laminated bamboo lumber(LBL)–a bamboo-based structural material,have been extensively studied using experimental,analytical,and numerical approaches.This paper presents a review of existing knowledge in the literature about the mechanical properties of LBL.The paper involved the review of the response of LBL to different types of loading such as tension,bending,compres-sion,and shear.Based on results of the literature reviewed,the strength of LBL parallel to grain was 90–124 MPa with MOE of 10700 MPa in tension,29.55–72.60 MPa,and MOE of 8396–11022 MPa in compression,63.87–128.4 MPa,and MOE of 8320–10912 MPa in bending,and 7.15–17.5 MPa in shear.The average strength of LBL was similar and in some cases exceeded the average values of bamboo-or wood-based materials,while the variability of its mechanical parameters was lower.The variability in strength values of LBL was affected by bamboo species,density and thickness of bamboo strips,growth portion,type of treatment,strips arrange-ments,and type of adhesive which in turn calls for classification of LBL by strength grades,degree of hardness,the capability of impregnation and penetration,as well as by areas of application in construction.The study pro-vided and discussed concluding observations,the current research gap,and future research directions on the mechanical properties of LBL.展开更多
This research studied the ultimate bearing capacity of laminated bamboo lumber(LBL)unit and thereby calculated the maximum bending moment.The load-displacement chart for all specimens was obtained.Then the flexural ca...This research studied the ultimate bearing capacity of laminated bamboo lumber(LBL)unit and thereby calculated the maximum bending moment.The load-displacement chart for all specimens was obtained.Then the flexural capacity of members with and without bamboo nodes in the middle section was coMPared.The bending experiment phenomenon of LBL unit was concluded.Different failure modes of bending components were analysed and concluded.Finally,the bending behaviour of LBL units is coMPared with other bamboo and timber products.It is shown that the average ultimate load of BS members is 866.1 N,the average flexural strength is 101 MPa,the average modulus of elasticity is 8.3 GPa,and the average maximum displacement is 17.02 mm.The average ultimate load of BNS members is 1008.1 N,the average flexural strength is 118.02 MPa,the average modulus of elasticity is 9.9 GPa,and the average maximum displacement is 18.26 mm.Laminated bamboo lumber(LBL)unit without bamboo nodes(BNS)has relatively higher flexural strength coMPared with LBL unit with bamboo nodes(BS).The presence of bamboo nodes reduces the strength of the entire structure.Three failure modes were concluded for BS members,and two failure modes were observed for BNS members during the experimental process.According to a coMParison between the LBL unit and other products,the flexural strength and bending modulus of elasticity of the LBL unit are similar as bamboo scrimber and raw bamboo components,which is much higher than timber components.展开更多
Eccentric compression tests on 15 chamfered laminated bamboo lumber(LBL)columns with a height ranging from 600 to 3000 mm were conducted in order to study the eccentric mechanical performance.The failure of all specim...Eccentric compression tests on 15 chamfered laminated bamboo lumber(LBL)columns with a height ranging from 600 to 3000 mm were conducted in order to study the eccentric mechanical performance.The failure of all specimens was caused by the crack of bamboo fiber in the tensile region.When the ultimate strength was reached,except specimens with a height of 600 mm,all other specimens could bear large deformation,showing good ductility.The lateral displacements of the specimens under eccentric compression were approximately para-bolic in the direction of column height.The ultimate bending moment of LBL columns with different slenderness ratios under compression with the same initial eccentricity was a fixed value.The relationship between ultimate capacity,axial displacement,lateral displacement,and slenderness ratio was analyzed based on test results.It was found that the plane section assumption could be used to express the stress and strain distribution of chamfered LBL columns under eccentric compression.A method for calculating the ultimate bearing capacity was proposed using a constitutive model based on the Ramberg-Osgood relation and the empirical formula for calculating the ultimate capacity was given on the basis of the former research as well as the test results in this paper.展开更多
为了缓解全球变暖的严峻形势,响应“2030碳达峰、2060碳中和”目标,实现建筑业绿色可持续发展,研究选定竹集成材为研究对象,利用碳排放因子法,识别并探讨竹建筑材料全生命周期的碳源和碳汇。在实地调研的基础上,分析了竹集成材在生产制...为了缓解全球变暖的严峻形势,响应“2030碳达峰、2060碳中和”目标,实现建筑业绿色可持续发展,研究选定竹集成材为研究对象,利用碳排放因子法,识别并探讨竹建筑材料全生命周期的碳源和碳汇。在实地调研的基础上,分析了竹集成材在生产制作、材料运输及施工安装阶段的资源消耗量和碳排放,研究了原竹种植与竹建筑构件拆除回收阶段的碳汇特性。研究发现:单位体积(1 m^(3))的竹结构建筑构件全生命周期的平均碳足迹为-187 kg CO_(2),碳汇可能性达67.06%,即竹建筑材料的全生命周期碳足迹总体表现为碳汇,有利于控制气候变暖。在对比分析了不同建筑构件在物化阶段的碳足迹后,明确了竹建筑材料的碳储存优势。展开更多
基金supported by the Natural Science Foundation of Jiang-su Province(No.BK20181402)the National Natural Science Foundation of China(51878354)+3 种基金National Key R&D Program of China,the Open Fund Project from Key Laboratory of Concrete and Pre-stressed Concrete Structure of Ministry of Education(Southeast university)the China Postdoctoral Science Foundation(2015M580382)Jiangsu Postdoctoral Science Foundation Project(1501037A)Qing Lan Project,and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘In order to investigate the influence of length and compression directions upon behaviour of parallel bamboo strand lumber(PBSL)specimens,240 axial compression tests have been performed.With three similar one different typical failure modes,the mechanical performance for PBSL specimens under compression parallel to grain and perpendicular to grain are different as a whole.From the point of the characteristic values,the compression strength parallel to grain is 2.1 times of the compression strength perpendicular to grain.The elastic modulus for compression parallel to grain is 3.64 times of the compression strength perpendicular to grain.While the compression ratios along two compression directions are equal to each other.The bigger Poisson ratios for one typical side surface is 3.93 times of that for another typical side surface for PBSL specimens under compression perpendicular to grain,and the bigger value is equal to that for PBSL specimens under compression parallel to grain.Length can influence the mechanical properties of the PBSL specimens.The size 50 mm×50 mm×100 mm should be good choice for the standard or code to measure the compression strength.PBSL materials have better ductility under compression parallel to grain than that under compression perpendicular to grain.Stress-strain relationship models were proposed for PBSL specimens under compression parallel to grain and perpendicular to grain,respectively.These proposed models gave a good agreement with the test results.
基金The research work presented in this paper is supported by the National Natural Science Foundation of China(Nos.51878354&51308301)the Natural Science Foundation of Jiangsu Province(Nos.BK20181402&BK20130978)+1 种基金Six Talent Peak High-Level Projects of Jiang su Province(No.JZ029)Qinglan Project of Jiangsu Higher Education Institutions.Any research results expressed in this paper are those of the writers and do not necessarily reflect the views of the foundations.
文摘Over the past decade,the physical and mechanical performances of laminated bamboo lumber(LBL)–a bamboo-based structural material,have been extensively studied using experimental,analytical,and numerical approaches.This paper presents a review of existing knowledge in the literature about the mechanical properties of LBL.The paper involved the review of the response of LBL to different types of loading such as tension,bending,compres-sion,and shear.Based on results of the literature reviewed,the strength of LBL parallel to grain was 90–124 MPa with MOE of 10700 MPa in tension,29.55–72.60 MPa,and MOE of 8396–11022 MPa in compression,63.87–128.4 MPa,and MOE of 8320–10912 MPa in bending,and 7.15–17.5 MPa in shear.The average strength of LBL was similar and in some cases exceeded the average values of bamboo-or wood-based materials,while the variability of its mechanical parameters was lower.The variability in strength values of LBL was affected by bamboo species,density and thickness of bamboo strips,growth portion,type of treatment,strips arrange-ments,and type of adhesive which in turn calls for classification of LBL by strength grades,degree of hardness,the capability of impregnation and penetration,as well as by areas of application in construction.The study pro-vided and discussed concluding observations,the current research gap,and future research directions on the mechanical properties of LBL.
基金The research work presented in this paper is supported by the National Natural Science Foundation of China(Nos.51878354&51308301)the Natural Science Foundation of Jiangsu Province(Nos.BK20181402&BK20130978)practical and innovation training project of Nanjing Forestry University(2019NFUSPITP0496,2020NFUSPITP0378,202010298039Z).Any research results expressed in this paper are those of the writers and do not necessarily reflect the views of the foundations。
文摘This research studied the ultimate bearing capacity of laminated bamboo lumber(LBL)unit and thereby calculated the maximum bending moment.The load-displacement chart for all specimens was obtained.Then the flexural capacity of members with and without bamboo nodes in the middle section was coMPared.The bending experiment phenomenon of LBL unit was concluded.Different failure modes of bending components were analysed and concluded.Finally,the bending behaviour of LBL units is coMPared with other bamboo and timber products.It is shown that the average ultimate load of BS members is 866.1 N,the average flexural strength is 101 MPa,the average modulus of elasticity is 8.3 GPa,and the average maximum displacement is 17.02 mm.The average ultimate load of BNS members is 1008.1 N,the average flexural strength is 118.02 MPa,the average modulus of elasticity is 9.9 GPa,and the average maximum displacement is 18.26 mm.Laminated bamboo lumber(LBL)unit without bamboo nodes(BNS)has relatively higher flexural strength coMPared with LBL unit with bamboo nodes(BS).The presence of bamboo nodes reduces the strength of the entire structure.Three failure modes were concluded for BS members,and two failure modes were observed for BNS members during the experimental process.According to a coMParison between the LBL unit and other products,the flexural strength and bending modulus of elasticity of the LBL unit are similar as bamboo scrimber and raw bamboo components,which is much higher than timber components.
基金This study was funded by the National Natural Science Foundation of China(Nos.51878354&51308301)the Natural Science Foundation of Jiangsu Province(Nos.BK20181402&BK20130978)+2 种基金Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX20_0885)Six talent peak high-level projects of Jiangsu Province(No.JZ-029)Qinglan Project of Jiangsu Higher Education Institutions.
文摘Eccentric compression tests on 15 chamfered laminated bamboo lumber(LBL)columns with a height ranging from 600 to 3000 mm were conducted in order to study the eccentric mechanical performance.The failure of all specimens was caused by the crack of bamboo fiber in the tensile region.When the ultimate strength was reached,except specimens with a height of 600 mm,all other specimens could bear large deformation,showing good ductility.The lateral displacements of the specimens under eccentric compression were approximately para-bolic in the direction of column height.The ultimate bending moment of LBL columns with different slenderness ratios under compression with the same initial eccentricity was a fixed value.The relationship between ultimate capacity,axial displacement,lateral displacement,and slenderness ratio was analyzed based on test results.It was found that the plane section assumption could be used to express the stress and strain distribution of chamfered LBL columns under eccentric compression.A method for calculating the ultimate bearing capacity was proposed using a constitutive model based on the Ramberg-Osgood relation and the empirical formula for calculating the ultimate capacity was given on the basis of the former research as well as the test results in this paper.
文摘为了缓解全球变暖的严峻形势,响应“2030碳达峰、2060碳中和”目标,实现建筑业绿色可持续发展,研究选定竹集成材为研究对象,利用碳排放因子法,识别并探讨竹建筑材料全生命周期的碳源和碳汇。在实地调研的基础上,分析了竹集成材在生产制作、材料运输及施工安装阶段的资源消耗量和碳排放,研究了原竹种植与竹建筑构件拆除回收阶段的碳汇特性。研究发现:单位体积(1 m^(3))的竹结构建筑构件全生命周期的平均碳足迹为-187 kg CO_(2),碳汇可能性达67.06%,即竹建筑材料的全生命周期碳足迹总体表现为碳汇,有利于控制气候变暖。在对比分析了不同建筑构件在物化阶段的碳足迹后,明确了竹建筑材料的碳储存优势。
