1955 , .
1. (). (), () .
- , ( , , );
- ( , );
- ,
.
, ; , .
, , :
I- - (, , ); I- III II - .
II- - ( , ).
-I . -I, , . :
I- - () ,
M £ Mu - ; (7.4)
N £ Nu - (7.5)
M N - ( ) ;
Mu Nu - ( ) ().
II- - . ,
M = Mu (7.6)
N = Nu (7.7)
. , , .
-II , ; . -II - ( Ia), ( II ). .
2. . ( ) :
- ;
- ;
- .
( ). :
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- gf, ;
- gbc, gbt gs, ;
- gbi gsi, , ;
- gn, .
, - , - , .
. . - qn. , ..
q = qn ´ gf ´ gn. (7.8)
gf .
- , ;
- : ; ; ( , ..).
, .
:
( + + );
( + ).
, .
y = 1, , y = 0,9 yl = 0,95 . .
. . , , , - .
. n ( ) - R ( ) (. 41). , Rm , .. . . , , .
. 41. : ; -
( ) :
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h = 0 (.. R = Rm) - p = 0,5;
h = s - p = 0,68;
- " " " " - h = 2 s - p = 0,964;
- " " " " - h = 3 s - p = 0,9974.
, () K, p , n + 1
Rm ks, (7.9)
Rm - ks.
( ) p = 0,95, k = 1,64. , () 0,95, ( )
B º Rmin = Rn = Rm - 1,64 s = Rm (1 - 1,64 ) = Rm (1 - 1,64 v), (7.10)
v = s / Rm - () ; v = 0,135.
, , 5%, .. 0,95.
, , , , . , (.. v = 0,135) .
:
- ( )
Rb , n = B (0,77 - 0,00125 B), 0,72 ; (7.11)
- Rbt , n.
52-01-2003 .
, 0,95, () . , (, , , ..).
g b
-
Rb = Rb , n / g bc; (7.12)
-
Rbt = Rbt , n / g bt; (7.13)
I- gbc = 1,3 g bt = 1,5.
II- gbc = g bt = 1, ..
Rb , ser = Rb , n Rbt , ser = Rbt , n . (7.14)
, I- , II- ( 0,997 0,95). , .. -I (, , , ..), -II, .
Rsn 0,95:
, - sy s 0,2 ;
- 75% .
gs:
I-
Rs = Rsn / gs, (7.15)
gs > 1 ;
II-
Rs , ser = Rsn / gs; gs = 1. (7.16)
Rsc ( ) eb , u, 2×10-3 2,5×10-3 , ..
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Rsc = eb , uEs = (22,5)×10-3×2×105 = 400500 . (7.17)
. -I , ( , , ). , , . gbi gsi, . - gb 1, .
¨
I- . 1.
II- .
1. . .
, :
1- - ;
2- - (.. ), () ;
3- - .
, 1- 2- , , 3- - , . :
acrc 1 - ;
acrc 2 - ,
.
:
£ Mcrc - ;
N £ Ncrc - ,
M, N - ;
Mcrc, Ncrc - .
acrc £ acrc 1 - ..;
acrc £ acrc 2 - ...
(, , .) flim (. )
f £ flim.
gf .