Answer: Load in sub-truss: w=5x10=50kN/m,M'max=(1/8)wL2=(1/8)x50x10x10=625kNm If 0=60,h=1.73m,it is the first choice for sub-truss structure. N=625/1.73=361kN,stress-=N/A=361000/2500=144.5Mpa<200Mpa,OK! Check shear,Qmax=250kN,Ns=250/0.866=289kN,OK! For most economical purpose,0 can be changed as 51,h=1.25m,so that the maximal stress in sub-truss can reach 200Mpa,h=1.25m,N=500kN Load in main truss:P=w'x5=250kN, Mmax=7.5x0.5P+2.5xP=6.25P=6.25x250=1562.5kNm If 0=60,h=4.325m,it is the first choice for main truss structure. N=1562.5/4.325=361kN,Stress=-N/A=361000/2500=144Mpa,OKI Check shear,Qmax=500kN,Ns=500/0.866=577kN,Stress=N/A=231>200Mpa Fail! The tube with 50cm2 can be used in main truss with 0=32,h=1.563m N=1562.5/1.563=1000kN,Stress-=1000/5000=200Mpa,OK Qmax=500kN,Ns=500x1.89=945kN,Stress=N/A=189<200Mpa OK Weight of sub-truss-=8(10+8+10x1.6)x0.0025x7850=5.338T Weight of main truss=-2(35+30+14x2.95)0.005x7850=8.344T Cost=(5.338+8.344)10000=136820RMB
Answer: Load in sub-truss: w’=5x10=50kN/m, M’max=(1/8)w’L²=(1/8)x50x10x10=625kNm If θ=60, h=1.73m, it is the first choice for sub-truss structure. N=625/1.73=361kN, stress=N/A=361000/2500=144.5Mpa<200Mpa, OK! Check shear, Qmax=250kN,Ns=250/0.866=289kN, OK! For most economical purpose, θ can be changed as 51, h=1.25m, so that the maximal stress in sub-truss can reach 200Mpa, h=1.25m, N=500kN Load in main truss: P=w’x5=250kN, Mmax=7.5x0.5P+2.5xP=6.25P=6.25x250=1562.5kNm If θ=60, h=4.325m, it is the first choice for main truss structure. N=1562.5/4.325=361kN, Stress=N/A=361000/2500=144Mpa, OK! Check shear, Qmax=500kN, Ns=500/0.866=577kN, Stress=N/A=231>200Mpa Fail! The tube with 50cm² can be used in main truss with θ=32, h=1.563m N=1562.5/1.563=1000kN, Stress=1000/5000=200Mpa, OK Qmax=500kN, Ns=500x1.89=945kN, Stress=N/A=189<200Mpa OK Weight of sub-truss=8(10+8+10x1.6)x0.0025x7850=5.338T Weight of main truss=2(35+30+14x2.95) 0.005x7850=8.344T Cost=( 5.338+8.344)10000=13 6820RMB
Chapter 8 Horizontal Linear Components 8.1.Sectional Shapes and Proportions 8.2.Moment Diagrams 8.3.Internal Resisting Couple 8.4.Prestressing Design 8.5.Connections
Chapter 8 Horizontal Linear Components 8.1. Sectional Shapes and Proportions 8.2. Moment Diagrams 8.3. Internal Resisting Couple 8.4. Prestressing Design 8.5. Connections
8.1.Sectional Shapes and Proportions Horizontal linear components are variously named as slabs,beams,joist or girders,with shear,bending,torsion and axial force in these components
8.1. Sectional Shapes and Proportions Horizontal linear components are variously named as slabs, beams, joist or girders, with shear, bending, torsion and axial force in these components
To design a component,the first step is to determine approximate span/depth ratio. The L/d ratio will depend upon the material(concrete,steel), the loading, the sectional shape(I,H,T,L), the support conditions(simple,continue)
To design a component, the first step is to determine approximate span/depth ratio. The L/d ratio will depend upon - the material(concrete, steel), - the loading, - the sectional shape(I,H,T,L), - the support conditions(simple, continue)
8-1 水平分体系及简支构件的近似跨高比·® 平均 最大值 跨度心 (英尺) 平均值 最大值 游度心 值 (英尺) 【,木结构： 主梁 12 16 20~60 胶合木 36 40 35 门式框架 24 % 40-80 木板 28 32 2-6 拱（跨度/拱高）， 8 12 (拱60150) 次梁 22 26 10-25 空馥桁架 案 16 20 15-30 拱（跨度/拱厚） 30 40 主粱 12 16 2035 筒形薄壳屋盖 门式框架 26 呢 30-50 (可能由最小厚 桁架 8 30~100 度控制) 【,工字形粱及次梁 18 梁24，次粱25 1560 纵向跨度/矢高 12 15 50~70 板和工字形主粱 泉 20 40~100 横向跨度/壳厚 50 % 1230 桁架 12 18 40→80 V,预应力混凝土 门式框架 30 40 50~120 实心板（单向或 40 44 20-35 拱（畸度/拱高） 8 16 80~200 双向) (跨度/拱厚) % 50 有柱帽的板或支 44 48 35~45 悬索（跨度/高） 10 15 150300 承在梁上的双向板 拉索结构 6 10 150-300 双向密肋板 28 皂 35~70 【,钢筋混凝土： (跨度为2~10英尺的压型钢 空心板 36 40 30~60 板上的现浇混凝土板取25) 次梁 32 36 40-60 实心板（单向或 28 32 1025 梁 24 28 30~80 双向) 主梁 20 24 40120 有柱帽的板 简形薄充屋蓖 (或支承在梁上 30 20~35 的双向板) (可能由最小厚 双向密肋板 20 24 30-40 度控制) 次粱 22 26 25~45 纵向跨度/矢高 15 20 (60~120) 架 16 20 15~40 横向跨度/壳厚 60 70 1535 0悬臂梁的跨高比和跨度，取表中值的1/3， ©两增固定的次粱、梁和主粱，跨高比可增加10%， 371