一、设计资料1.结构形式某厂房跨度为24m,总长120m,柱距6m,采用梯形钢屋架、1.5×6.0m预应力混凝土大型屋面板,屋架铰支于钢筋混凝土柱上,上柱截面400×400,混凝土强度等级为C20,屋面坡度为i=1:10。2.屋架形式及选材屋架跨度为24m,屋架形式、几何尺寸及内力系数如附图所示。屋架采用钢材及焊条为:钢材选用Q345钢,焊条采用E50型。3.荷载标准值(水平投影面计)①永久荷载:二毡三油防水层0.4KN/m280mm泡沫混凝土保温层0.4KN/m2水泥砂浆找平层0.4KN/m21.5*6m预应力混凝土大型屋面板1.4KN/m2屋架及支撑自重(按经验公式q=0.12+0.011L计算)0.384KN/m2悬挂物及管道0.1KN/m2②可变荷载屋面活荷载标准值0.5KN/m2雪荷载标准值0.7KN/m2积灰荷载标准值0.3KN/m24.屋架的计算跨度:Lo=24000-2×150=23700mm,端部高度:h=2005mm(轴线处),h=2990mm(计算跨度处)。起拱h=50mm二、结构形式与布置图屋架支撑布置图如下图所示图一:24m跨屋架(几何尺寸)图二:24m跨屋架全跨单位荷载作用下各杆的内力值图三:24m跨屋架半跨单位荷载作用下各杆的内力值三、荷载与内力计算1.荷载计算永久荷载标准值:二毡三油(上铺绿豆砂)防水层0.4KN/m2水泥砂浆找平层0.4KN/m2保温层0.4KN/m2预应力混凝土大型屋面板1.4KN/m2屋架及支撑自重(按经验公式q=0.12+0.011L计算)0.384KN/m2悬挂管道0.1KN/m2_________________________________________________________________总计:3.184KN/m2可变荷载标准值:雪荷载0.7KN/m2大于屋面活荷载标准值0.5KN/m2,取0.7KN/m2积灰荷载标准值0.3KN/m2_______________________________________________________________总计1.0KN/m2永久荷载设计值:1.35×3.184=4.30KN/m2可变荷载设计值:1.4×1.25=1.75KN/m22.荷载组合设计屋架时,应考虑如下三种荷载组合:(1)全跨永久荷载+全跨可变荷载屋架上弦节点荷载F=(4.30+1.75)×1.5×6=54.45KN(2)全跨永久荷载+半跨可变荷载屋架上弦节点荷载F1=4.30×1.5×6=38.71KNF2=1.75×1.5×6=15.75KN(3)全跨屋架和支撑自重+半跨大型屋面板重+半跨屋面活荷载屋架上弦节点荷载F3=0.384×1.35×1.5×6=4.667KNF4=(1.5×1.35+1.4×0.5)×1.5×6=24.53KN3.内力计算本设计采用图解法计算杆件在单位节点力作用下各杆件的内力系数。表一:屋架杆件内力组合表杆件名称内力系数(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左半全跨②右半全跨③F1×①+F2×②F1×①+F2×③F3×①+F4×②F3×①+F4×③AB0.000.000.000.000.000.000.000.000.000上弦BCD-8.72-6.25-4.27-474.80-435.90-404.72-202.13-150.93-474.80DEF-13.5-9.04-4.49-736.71-665.99-594.33-296.65-179.03736.71FGH-15.2-9.17-6.09-830.91-743.99-686.78-308.08-228.42830.91HI-14.7-7.38-7.38-800.96-685.13-685.13-259.28-259.17-800.96下弦ac4.733.841.25257.55202.74202.74121.26254.3293257.55ce11.5383.53627.81501.81501.81260.451144.91627.81eg14.659.345.31797.69650.59722.596309.624205.426797.69gi15.178.446.73826.01693.08693.08288.804244.528826.01斜腹杆aB-8.87-6.53-2.34-482.97-446.12-380.12-210.07-101.78-482.97Bc6.884.762.12374.62341.23299.65155.0686.8204374.62cD-5.44-3.14-2.3-296.21-258.98-246.75-106.49-84.759-296.21De3.71.91.8201.47173.12171.5466.344963.736201.47eF-2.46-0.71-1.75-133.95-106.38-122.76-29.82-56.666-133.95Fg1.11-0.451.5660.4435.8767.53-6.443145.467467.53-6.44gH0.021.55-1.531.0925.19-23.3240.1298-39.42740.13-39.426Hi-1.08-2.471.69-58.81-80.70-15.18-68.8438.6199-80.7038.62竖杆Aa-0.5-0.50-27.23-27.23-19.35-15.249-2.33-27.23Cc-1-10-54.45-54.45-38.70-30.497-4.66-54.45Ee-1-10-54.45-54,45-38.70-30.497-4.66-54.45Gg-1-10-54.45-54.45-38.70-30.497-4.66-54.45Ii1.940.970.97105.6390.3690.3657.32-48.45105.63四、杆件截面设计腹杆最大内力-482.97kN,查表得,中间节点板厚度选用10mm,支座节点板厚度选用12mm。1.上弦杆(FGH杆)整个上弦不改变截面,按最大内力-...