求应力 bhz3120×180 ×10 12 5.832×10 12 =6.48×10 q=60KN/m h/2 H□ B 60×60 ×103=617MPa 5.832 M160 I max ×104=926MPa W.6.48 67.5 M q max ×104=104.2MPa max W648求应力 1 2 5 4 3 3 10 5.832 10 12 120 180 12 m bh I z − −  =   = = 4 3 6.48 10 / 2 m h I W z z − = =  MPa I M y z 10 61.7 5.832 1 60 60 5 1 2  = −   =  = = MPa W M z 10 92.6 6.48 1 60 4  1max = =  = MPa W M z 10 104.2 6.48 max 67.5 4  max = =  = /8 2 qL