, , , 
. 4 [1].
, 
I, I, l, l . . 5
N =-2315,61;
N =-419,72 ;
. 4 [1], 
140 [1]
.
(.5 [1])
, 
=2,52.
140 [1]
.
.
.
:
:
1. . .1 [1]. 245, t=2-20 Ry=240/2. E=2,06105/2.
2. h=0,5 .
3.
- 
;
- 
.
4. M =318,03; N=-304,52 .
:
1. - 
;
2. - 
;
3. - 
;
4. - 
5. N - 
1,05=105
6. - 
7. - 
, 
=1,25- , . .2 [1], 5,
.
8. . 9.1.2 [1] f ≤ 20 - , , .
=0,19- . .3 [1], 
=2,41 
=5,4.
=1,05 . 1[1].( ).
:
( 
=1).
) .
)
4
) 
,
=0,8 , 
= 48;
=48*0,8 =38,42.
bf=20 , tf=1 ; 
