0mР长细比λ= l0/i = 6000/39 = 154 < [λ] = 200Р按b类截面查表取整体稳定系数φ= 0.295РN/(φA) = 57.45×103/(0.295×1045) = 186MPa < f = 215MPaР满足要求。Р(4) 斜腹杆验算:Р斜腹杆计算长度l0 = 7.50mР长细比λ= l0/i = 7500/35 = 215 < [λ] = 350РN/A = 67.98×103/934 = 72.8MPa < f = 215MPaР满足要求。Р二、下柱支撑计算Р(1)吊车荷载:Р30m跨内(一台32t和一台10t吊车)Р32t吊车纵向水平荷载计算:Р最大轮压Pmax = 35 t,每侧2个轮子Р纵向水平荷载标准值Tz = 0.1×2×Pmax×9.8 = 70.0kNР10t吊车纵向水平荷载计算:Р最大轮压Pmax = 16.3 t,每侧2个轮子Р纵向水平荷载标准值Tz = 0.1×2×Pmax×9.8 = 32.6kNР24m跨内(两台10t吊车)Р10t吊车纵向水平荷载计算:Р最大轮压Pmax = 13.8 t,每侧2个轮子Р纵向水平荷载标准值Tz = 0.1×2×Pmax×9.8 = 27.6kNР总纵向水平荷载标准值(未考虑折减):Р 27.6*2+70+32.6=157.8kNР(3)支撑内力计算:Р本工程共设三道下柱支撑,且每道都是双片支撑,偏安全地取每片支撑的荷载设计值为:1.4*157.8/2=110.46kN。下柱支撑按柔性受拉斜杆设计,得到设计荷载作用下支撑内力值如右图所示。Р(4) 斜腹杆验算:Р斜腹杆计算长度l0 = 10.445mР长细比λ= l0/i = 10445/54.6 = 191 < [λ] = 200РN/A = 192.29×103/2184 = 88.1MPa < f = 215MPaР满足要求。
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