练习: 3kN. m 2 3 (3) 作弯矩图 420 1/2 4206 f 0){F 24|1-1/4 21246 1/4 04818({6(0 841-1/ 6,=6,=0 480 100 0120δ 0016 12 2i 1 =1 i 2 = 2 3kN.m 作弯矩图 练习: 1 2 3 (1) (2) (3) 1 2           = −                     3 1 3 2 1 3 0 4 8 2 12 4 4 2 0 P P    0  1 =  3 =           = −                     0 3 0 0 0 1 0 12 0 1 0 0 3 2 1              = −           0 1/ 4 0 3 2 1            − − =       −       = 1 1/ 2 1/ 4 0 2 4 1 4 2 F         − − =      −       = 1 2 0 1/ 4 4 8 2 8 4 F 1/2 M 1 2 1