④x=fg4-280x1250=1522mm Jab11.5x200 5元=02785<=056 同M.=bmh- =15×20x1522×5465-1523)=164656154N-mm=164.66K.m 2 ④ 11.5 200 280 1250   = = f b f A x cd sd s =152.2mm 0 0.2785 0.56 b x h   = =  = ⑤ 0 ( ) 2 u cd x  = − M f bx h =    − ) = 164656154N  mm = 164.66KN  m 2 152.2 11.5 200 152.2 (546.5