钢结构课程设计18米跨度

钢结构课程设计1、设计题目题目详见附件。屋架计算跨度：l0=21-2×0.15=20.7m屋架的中间高度：h=3.040m在20.07m的两端的高度：h0=2.005m在30m轴线处端部高度：h0=1.990m屋架跨中起拱42mm2、结构形式与布置屋架形式与几何尺寸如图119901350229025902890304026132864312425302864312433901507.51507.51507.51507.51507.51507.51507.5150AaceghBCDFGH15007=10500×屋架支撑布置如图2图2垂直支撑2-2垂直支撑1-1屋架下弦支撑布置图屋架上弦支撑布置图21213、荷载计算荷载与雪荷载不会同时出现，故取两者较大的活荷载计算。屋架沿水平投影面积分布的自重按经验公式计算，跨度的单位为m。荷载永久荷载：预应力砼屋面板1.45×1.005=1.457kN/m2三毡四油（上铺绿豆砂）防水层0.4×1.005=0.402kN/m2水泥砂浆找平层1.005×0.4=0.402kN/m2保温层0.4×1.005=0.402kN/m2屋架和支撑自重0.12+0.011×21=0.351kN/m2管道荷载0.182kN/m2一毡二油隔气层0.05×1.005=0.050kN/m2水泥砂浆找平层1.005×0.0.3=0.302kN/m2________________________________________________总计3.541kN/m2可变荷载：屋面活荷载0.8kN/m2积灰荷载1.1kN/m2设计屋架时，应考虑以下3种荷载组合：(1)全跨永久荷载+全跨可变荷载(按永久荷载为主控制的组合)全跨节点荷载设计值F=（1.35×3.541+1.4×0.7×0.8+1.4×0.9×1.1）×1.5×6=62.553kN(2)全跨永久荷载+半跨可变荷载全跨节点永久荷载F1=3.2299×1.5×6=29.0691kN半跨节点可变荷载F2=2.1×1.5×6=18.9kN组合三全跨屋架及支撑自重+半跨大型屋面板重+半跨屋面活荷载全跨节点屋架自重F3=0.54×1.5×6=4.86kN半跨节点屋面自重及活荷载F4=（1.68+2.1）×1.5×6=34.02kN组合一、二为使用阶段荷载情况，组合三为施工阶段荷载情况。4、内力计算屋架在上诉三种荷载组合作用下的计算简图见图3由电算先解得F=1的屋架各杆件的内力系数（F=1作用于全跨、左半跨和右半跨），然后求出鸽子荷载情况下的内力组合，计算结果见表1F/2FFFFFFFFFFF/2FF3F3/2ABCDEFGacegF1/2F1F1F1F1F1F1F1F1F1F1F1/2F1F2/2F2F2F2F2F2F2/2F3F3F3F3F3F3F3F3F3F3F3/2F4/2F4F4F4F4F4F4/2bca图3、屋架计算简图屋架构件内力组合表表1杆件名称内力系数（F=1）第一种组合F×①第二种组合第三种组合计算杆件内力（KN）全跨①左半跨②右半跨③F1×①+F2×②F1×①+F2×③F3×①+F4×②F3×①+F4×③上AB0000.0000.0000.0000.0000.0000.000BC,CD-6.221-4.371-1.850-298.416-263.451-215.804-178.935-93.171-298.416弦DE,EF-8.993-5.636-3.357-431.386-367.939-324.866-235.443-157.911-431.386FG-9.102-4.551-4.551-436.615-350.601-349.826-199.061-199.061-436.615下弦ac3.4702.5370.933166.453148.819118.503103.17348.605166.453ce7.9625.3252.637381.930332.091281.287219.852128.406381.930eg9.2795.3123.967445.105370.129344.708225.810180.053445.105斜腹杆aB-6.502-4.754-1.748-311.895-278.858-222.044-193.331-91.067-311.895Bc4.7393.1581.581227.326197.445167.639197.00276.817227.326cD-3.382-1.862-1.520-162.231-133.503-127.040-79.782-68.147-162.231De1.8840.5401.34490.37464.97280.16827.52754.87990.374eF-0.6900.615-1.305-33.099-8.434-44.72217.569-47.75017.569-44.722Fg-0.462-1.6321.170-22.162-44.2758.683-57.76637.55837.558-57.766竖杆Aa-0.5-0.50-23.985-23.985-14.535-19.440-2.430-23.985Cc,Ee-1.0-1.00-47.969-47.969-29.069-38.880-4.86-47.969Gg0.8120.4060.40638.95131.27831.27817.75817.75838.9515、杆件设计2L160X100X1010（1）上弦杆整个上弦采用等截面，按FG杆件之最大设计内力设计。N=-436.615KN=-436615N上弦杆计算长度在屋架平面内：为节间轴线长度l0x=150.75cm在屋架平面外：根据支撑布置和内力变化情况，取l0y=150.75×3=452.25cm因为3l0x=l0y，故截面宜选用两个不等肢角钢短肢相并。腹杆最大内力N=-311.895KN，查表，节点板厚度选用10mm,支座节点板厚度用12mm.设λ=60，查附表得732.0。需要截面积fA=215732.0436615=2774.3mm2需要的回转半径：ix=l0x/λ=150.75/60=2.51cmiy=l0y/λ=452.25/60=7.54cm根据需要的A,ix,iy查附表，选用2∟160×100×10,A=50.63cm2,ix=2.85,iy=7.71,按所选角钢进行验算：λx=l0x/ix=150.75/2.85=52.89[λ]=150λy=l0y/iy=452.25/7.71=58.67[λ]=150满足长细比要求。由于λyλx,只需求y。查表得y=0.813N/yA=311895/(0.813×5063)=75.77N/mm2215N/mm2所需截面合适。(2)下弦杆件2L100X63X1010整个下弦杆采用同一截面，按最大内力所在的eg杆计算。N=445.105KNl0x=300cm,l0y=885cm需要截面积fA=445105/215=2070.26mm2选用2∟100×63×10A=3093.4mm22070.26mm2ix=1.74cm,iy=5.01cmλx=l0x/ix=300/1.74=172.41350λy=l0y/iy=885/5.01=176.65350(3)端弦杆aB2L100X63X1010杆件轴力N=-311895N计算长度l0x=l0y=253cm，因为l0x=l0y，故采用不等肢角钢长肢相并，选用2∟100×63×10ix=3.15cmiy=2.71cmA=3093.4mm2λx=l0x/ix=253/3.15=80.32λy=l0y/iy=253/2.71=93.36因为λxλy，只求y=0.475=N/yA=311895/（0.475×3093.4）=212.37N/mm2215N/mm2所选截面合适（4）竖杆Ee102L50X5N=-47969Nl0x=259×0.8=207.2cm,l0y=259cm设λ=150ix=l0x/λ=207.2/150=1.38cmiy=l0y/λ=259/150=1.73cm选用2∟63×5ix=1.53cm，iy=2.46cm，A=960.6mm2λx=l0x/ix=207.2/1.53=135.4﹤150λy=l0y/iy=259/2.46=105.3﹤150λx﹥λy，只求x=0.265=N/xA=47969/(0.265×960.6)=188.44N/mm2215N/mm2屋架杆件截面选择表杆件计算内力（KN）截面规格截面面积(cm2)长细比容许长细比[]名称编号λxλy上弦FG-436.615160×100×1050.6352.8958.67150下弦eg445.105100×63×1030.934172.41176.65350腹杆aB-311.895100×63×1030.93480.3293.36150Bc227.32656×510.83121.5397.14350cD-162.23175×1028.252101.3880.9150De90.37456×510.83133.21106.47350eF-44.72217.56970×513.75115.796.42150Fg-57.76637.55870×411.14114.6497.32150Aa-23.98545×58.584145.2688.05150Cc-47.96950×512.28694.4377.36150Ee-47.96950×512.286106.887.5150Gg38.95130×33.498317.58177.30350杆件计算长度（cm）回转半径（cm）稳定系数应力（N/mm2）名称编号l0xl0yixiyxy上弦FG150.75452.252.857.710.73275.77下弦eg3008851.745.01192.6腹杆aB2532533.152.710.475212.37Bc209.04261.31.722.69280.97cD229.12286.42.263.540.403190.73De229.12286.41.722.69111.7eF249.92312.42.163.240.45792.7Fg249.92312.42.183.210.462112.47Aa1991991.372.260.256154.39Cc183.22291.532.460.66893.45Ee207.22591.532.460.265188.44Gg2892890.911.63149.056、节点设计227.326KN47.969KN162.231KN166.453KN381.930KN2L100X63X102L75X108-8068-606-302L63X5178181402302102302L50X56-60（1）下弦节点“c”用焊条为E50型的抗拉，抗压，抗剪强度为fwf=200N/mm2。设“Bc”杆的肢背和肢尖焊缝hf=8mm和6mm，则所需的焊缝长度为：肢背:lw’=0.7N/2hefwf=0.7×227326/（2×0.7×8×200）=71.04mm取8cm肢尖:lw〞=0.3N/2hefwf=0.3×227326/（2×0.7×6×200）=50.70mm取6cm设“cD”杆的肢背和肢尖焊缝hf=8mm和6mm，则所需的焊缝长度为：肢背:lw’=0.7N/2hefwf=0.7×162231/（2×0.7×8×200）=51.95mm取6cm肢尖:lw〞=0.3N/2hefwf=0.3×162231/（2×0.7×6×200）=28.97mm取3cm“cC”杆的内力很小，焊缝尺寸可按构造确定，取hf=5mm.。根据上面的计算结果及相应的构件之间应有的制作和装配误差，确定节点板的尺寸为270mm×440mm.下弦与节点板的焊缝长度为440mm，hf=6mm。焊缝所受的力为左右两下弦杆的内力差N=51