西安建筑科技大学：《材料力学》课程习题与答案_第7章 简单超静定

第13次课作业 7F/4 FR(4a F(2a), 3Fa EA EA EA FB=7F(压力) 5F/4 2MA=O,FNI+2FN2a-3Fa=0 EA EA △l2=2A F,、=2F 3F =30kN,F2=60kN F,30000 30MPao=60mpa A1000 6-11 M M B M MR(2a) GI M,=32M M.M=-M 33 33

第 13 次课作业 6-1 (压力） 4 5 0 (4 ) (2 ) 3 F F EA Fa EA F a EA F a B B = − + + = 6-4 MPa MPa A F k N F k N F F F F l l EA F l l EA F l l M F a F a Fa N N N N N N N A N N 30 , 60 1000 30000 30 , 60 5 3 2 2 , 0, 2 3 0 2 1 1 1 2 2 1 2 1 2 2 1 1 1 2 = = = = = = = =  =   =  =  = + − =   6-11 A e B e A B P B P A A B e M M M M M M GI M a GI M a M M M 33 1 , 33 32 32 0 (2 ) 1 2 = = = − + = + = 7F/4 (+) F/4 (-) 5F/4

6-15(a) WB=WBE+WBF=O 9F.a BF 3EI EⅠ F(2a),F(2a) 14Fa BE 3EI 2El gEl 4 FF FM 27 27

6-15(a) F F F F M Fa EI Fa a EI F a EI F a w EI F a EI F a w w w w B A A B F B B B F B B F B F B B 9 4 , 27 13 , 27 14 3 14 2 (2 ) 3 (2 ) 9 3 .(3 ) 0 3 2 3 . 3 3 . . . = = = = +  = = − = − = + =