同济大学：《木结构 Timber Engineering》课程教学资源（电子教案）02 Strength of Wood

园 Words and Expressions Strength of Wood Log,qure luber,plank原木，方木，厚木板 防材 Dimenginn hnher 规格材 visually re-graded lumber木材目到分级 machine sr-ratedumber木材机械分级 nangle to grain斜纹 Words and Expressions 园 Words and Expressions 园 roadle 叶材 bendine resis空抗套径度 compressive resistance parallel to grain顺坟抗压强度 tensilesistan paralleoin 顺纹抗拉强度 shearine resistance parallel to grain 顺纹抗剪强度 compreperperdiculartogran承压强度 (1)entire surface金表面 (para时fce andh町ae局点长度承压 (3)nder tensile bolt washer局都长度和宽度承瓜 odof e的弹性模量 Strength of wood 1.Grades oftimber 胞 1.Grades of timber 2.Grades for conferous and broadleaf trees bcr".M..N.V.Mn. 3.Adjustment factor 4.Import dimension lumber 1

1 Strength of Wood Prof. Minjuan HE Tongji University, Shanghai China Words and Expressions Log, square lumber , plank 原木，方木，厚木板 Glued timber 胶合材 Dimension lumber 规格材 visually stress-graded lumber 木材目测分级 machine stress-rated lumber 木材机械分级 an angle to grain 斜纹 Words and Expressions Coniferous trees 针叶材 Broadleaf trees 阔叶材 Words and Expressions bending resistance 抗弯强度 compressive resistance parallel to grain 顺纹抗压强度 tensile resistance parallel to grain 顺纹抗拉强度 shearing resistance parallel to grain 顺纹抗剪强度 compression perpendicular to grain 承压强度 (1) entire surface 全表面 (2) part of surface and toothed surface 局部长度承压 (3) under tensile bolt washer 局部长度和宽度承压 modulus of elasticity 弹性模量 1.Grades of timber 2.Grades for coniferous and broadleaf trees 3.Adjustment factor 4.Import dimension lumber Strength of wood Log, square lumber and plank (used for sawn and round timber structures): Ⅰa , Ⅱa , Ⅲa Glued timber: Ⅰb , Ⅱb , Ⅲb Dimension lumber: Ⅰc , Ⅱc , Ⅲc ,Ⅳc ,Ⅴ c ,Ⅵ c ,Ⅶ c To grade According to the defects (decay, knots, slope of grain, checks, pith……) in timber 1. Grades of timber

1.Grades of timber 1.Grades of timber 园 (used for srwn and found 盘 1.Grades of timber 2.Grades for coniferous and broadleaf trees Tde4-1 hor ③Dimension humber。H.M.,N.V.V.lng Tale 3.1-1 Crade 2.Grades for coniferous and broadleaf trees h4上Srogh galo he bnsded ten == 2

2 (1) Log, sawn lumber and plank (used for sawn and round timber structures): Ⅰa, Ⅱa, Ⅲa 1. Grades of timber (2) Glued timber: Ⅰb , Ⅱb , Ⅲb 1. Grades of timber (3) Dimension lumber: Ⅰc , Ⅱc , Ⅲc ,Ⅳc ,Ⅴ c ,Ⅵ c ,Ⅶ c 1. Grades of timber 2. Grades for coniferous and broadleaf trees 2. Grades for coniferous and broadleaf trees Strength Grades TB20 TB17 TB15 TB13 TB11

3.Adjustment factor 3.Adjustment factor 园 3.Adjustment factor 3.Adjustment factor 426 g<。<0 恤deig yhe f opeahegin(m 3.Adjustment factor 园 4.Import dimension lumber

3 3. Adjustment factor (1) Uncut logs：If log applied have not been cut out the checking parts, the design values of compressive resistance strength and bending resistance strength parallel to grain and modulus of elasticity will be increased by 15%. (2) Large-size rectangular section：If the short side of the rectangular cross-section of a member is longer than 150mm, the design value of strength will be rise by 10%. (3) Wet timber：If the wet timber is used, the design values of compressive strength perpendicular to grain and modulus of elasticity concerning all kinds of timber will be decrease by 10%. The design value of flexural resistance strength of deciduous pine(落叶松) should be the same adjustment. 3. Adjustment factor (4) Different conditions 3. Adjustment factor (5) Varied design working life 3. Adjustment factor (6) Compressive strength at an angle to grain (斜纹) For glued timber structure, there is design values of strength in 《Technical code of glued laminated timber structures》 For imported timbers which have not been included in code, their mechanical indexes and main properties should be provided by exporting countries and will be determined by our country. 3. Adjustment factor 4. Import dimension lumber

4.Import dimension lumbe 园 4.Import dimension lumber :目目 4.Import dimension lumber 园 4.Import dimension lumbe there are design values of TE共作用系 4.Import dimension lumber 园 NOTE:emodifi3 ion factors尺寸调整系表 J.a.1-2

4 4. Import dimension lumber 4. Import dimension lumber 4. Import dimension lumber 4. Import dimension lumber For some import dimension lumber, there are design values of strength in our timber code. NOTE: composite action factor 共同作用系数 When the number of joists of dimension lumber is greater than 3 and is connected reliably with floors, roofs or other members, the bending resistance capacity of the joists shall be designed to multiply the design value of the bending resistance strength fm by the composite action factor of 1.15. 4. Import dimension lumber NOTE: size modification factors 尺寸调整系数