新繁高架盖梁托架内力计算(伸臂梁)

取1.3为安全系数q=1443.85*1.3/15.9=118.05KN/mР4.2工字梁受力分析:Р工字钢等级为Q235,弹性模量E=2.1*105MPa,泊松比σ=0.3 Р托架按外伸臂梁进行分析,最不利情况即跨中承受最大弯矩,受力计算模式见图2:Р选用两根I56b工字钢,其截面特性为:Ix =68510cm4 Wx = 2447cm3 Sx =1447.2cm3 Ix / Sx= 47.2cm, 腹板厚tw =14.5mm b=168mm 自重=1.15KN/mР考虑梁自重后,每根工字钢跨中最大弯矩为:Р= 1/2*(118.05/2+1.2*1.15)*9.1*7.9*((1-3.4/7.9)*(1+2*3.4/9.1)-7.9/9.1)Р=276.05KN.mmР图2:工字钢受力计算模式Р4.3 工字钢强度验算Р3.2.1 抗弯强度验算:Р = 276.05*106/(1*2447*103) = 112.8<f= 315 N/mm2 满足要求Р(式中gx为钢材容许应力提高系数取1.0,查材料表20Mnsi钢fsy=315Mpa)Р3.2.2 挠度验算: Р跨中Р=(5-24*(3.4/9.1)2)*(118.05/2+1.2*1.15)*103*9.14/(384*2.1*1011*68510*10-8)Р=0.0124m=12.4mm<[f]=L/400 =9100/400=22.75mm 满足要求РA点Р=(6*3.42/9.12+3*3.43/9.13-1)*(118.05/2+1.2*1.15)*103*3.4*9.13/(24*2.1*1011*68510*10-8)Р=-0.00027m=-0.27mm<[f]=L/400= 3400/400=8.5mm 满足要求Р4.4 钢销受力验算Р设计控制值:45#钢容许弯曲应力220MPa,剪应力为110MPa