0.8=0.42kn/m.Р活荷载q2=0.13kN/mР ɤG = 1.35РɤQ = 1.4Р(2)截面特性:Р钢管48*2.7mm,回转半径:1.6cm,截面积3.84cm2Р单位质量:3.01kg/m,W=9.89cm4,Р(3)抗弯强度验算:(6m)Рqd=1.35q1+1.4q2=0.749kN/mР钢管上荷载标准值:qk = q1+q2 = 0.55 kN/mР每根钢管长度上的荷载为 q =qd / 4 = 0.187 kN/mР跨中最大弯矩为(L =6 m)РMmax = 0.125 * q * L2 = 0.84kN/mР梁自重为 G = 3.016 *10 = 30.16N/mР梁弯矩为 Mg = 0.125 * G * ɤG * L2 = 203.58 N mР M = Mg + Mmax = 203.58 + 840 = 1043.58 N m Р(4)弯曲正应力Рσ=Р钢材的强度设计值 Q235钢抗拉,抗压和抗弯f = 215 Р所以σ= 100.48 < f = 215 Р抗弯强度满足要求。Р(5)抗剪强度验算Р支座处最大剪力Vmax = 0.5 * q * l = 0.5 * 0.187 * 3 = 280.5N Р自重的最大剪力 VG = G * ɤG * 2 = 40.716 N Р V = Vmax + VG = 321.216 N Рτ= 321.216 * 3.84 / 9.89 * 4.12 = 30.27 N/mm2Р钢材的强度设计值 Q235钢抗剪fv = 125 Р所以τ= 30.27N/mm2 < fv = 125 Р抗剪强度满足要求。Р(6)刚度验算Р简支钢梁的挠度容许值Р梁上荷载标准值 qk = q1+q2 = 0.55 kN/mР弯矩为 Mk = 0.125 * qk * l2 = 2.475 kN/mР刚度满足要求。
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