... 23 .0,8 13 8 ,1 = 1, 4. (2 . 1, 939 1) = 0, 42 1 324 ,3 hw (2 1) E ( 2. 1, 939 1) .2, 1. 10 = 4,35 = 4,35 2 tw (2 ) + + 1 324 ,3. (2 1, 939) + 1, 939 + 4.0, 42 E 2, 1. 10 = 11 74,6 > 3,8 = 3,8 = 11 8,76 f 21 50 ... Ibt w Vi : S c = 20 ,5 .1. 18 = 369cm t w h 1 ,2. 40 w = = 6400cm 12 12 25538 ,18 .369 = = 12 2 7,1kG / cm 6400 .1 ,2 Ib = td = 830 ,2 + 3. 12 2 7, 12 = 22 81, 8kG / cm < 1, 15f = 1, 15 . 21 50 = 24 72, 5kG / cm Vy ... 22 .2 35 .22 nh sau : Do 0 ,1 < < 40 nờn tớnh = 0,07 + 2, 25 = 0,07 .1, 31 + 2, 25 = 2, 3 42 17 76 35 2, 1. 10 = 2, 3 42 . = 14 ,25 > 0,85 15 115 1 52 21 50 d = 0,68 + 0 , 21 1 = 0,68 + 0 , 21 .14 ,25 ...