, b. .
b 2 5 .
b = L/n,
n = 4: = 20/4 = 5 .
n = 6: = 20/6 = 3,33 .
n = 8: = 20/8 = 2,5 .
n = 4 b = 5 .
1,5 3 .
= /n,
n = 2: = 7,5/2 = 3,75 .
n = 3: = 7,5/3 = 2,5 .
n = 4: = 7,5/4 = 1,875 .
n = 5: = 7,5/5 = 1,5 .
n = 5 = 1,5 . Pn = 22 /2 = 1,5 .1.1 [2] tn=12 . .2.2.1.
.2.2.1.
:
-
,
α , (1,01-1,02),
g
ρ ( 24 /3),
t .
-
γf.g ( 1,1).
(.2.2.2.):
-
b .
-
.2.2.2.
530 , .
:
c1 , , 1,1.
Ry 245 ( 2 20 240).
: 351 Wx = 581,73, Ix=10060 4 ( 26020-83) (.2.2.3.).
b=155 |
77,5 |
77,5 |
d=6,2 |
Y |
X |
.2.2.3. 351
1 .66. [1],
1 = 1,11.
:
.
, - .
:
.
:
|
|
-
g ( 1 ) /.
-
.
:
: 702 Wx = 41873, Ix = 145912 4 ( 26020-83) (.2.2.4.).
b=260 |
d=12,5 |
Y |
X |
.2.2.4. 702
1 .1.11. [1],
1 = 1,11.
:
.
, - .
:
qn ,
l ,
Ix (146000 4 702),
(f/l)u (1/250).
.
,
δ = (1 0,7) = 0,3,
lef = a = 1,5 ,
b = 26 c, t = 1,85 .
, .
lef = a/2 = 0,75 ,
1 2 . 1 200 .; 1 3 80 . ( , ).
= 80t = 800,12 = 9,6 /2 1 3 (t ),
= 0,2g/ = 0,238,9/1,5 = 5,19 /2 ,
= 0,2g/b = 0,2144,2/5 = 5,77 /2
(16,72 /2 < 20,56 /2) , .
3. 3