39-2剪力和弯矩及其方程例题921 2FI 求图示简支梁E截面的内力 Me=fa 解:1.确定支反力 15c"D ∑F,=0Fn+F2=2F ∑ M,=0 BY F.3a+ Fa= 2F B 2.用截面法研究内力 F 5F SE ∑F=02F+FsE=-n2 SE cEM∑M=02.a+M=32 5F 3a BFa E 2 目录解：1. 确定支反力 FAy FBy Fy = 0 FAy + FBy = 2F MA = 0 FBy 3a + Fa = 2F a 3 F FBy = 3 5F FAy = 2. 用截面法研究内力 FAy FSE ME Fy = 0 3 5 2 F F + FSE = ME = 0 2 3 3 5 2 2 F a M a F E  + =  3 F FSE = − 2 3Fa ME = ◼§9-2 剪力和弯矩及其方程 目录 例题9-2-1 求图示简支梁E 截面的内力 FAy