.
) αn ≤ ξR
(6.7) |
) αn > ξR
(6.8) |
ξ ,
(6.9) |
αs
(6.10) |
ξ1 = (αn + ξR)/2, 1,0.
(6.7 6.10):
. | (6.11) |
m , , m.
. S' S , , :
(6.12) |
(6.13) |
αR ξR - . 5 0,4 0,55;
5
240 | 300 | 400 | 500 | 500 | |
0,612 | 0,577 | 0,531 | 0,493 | 0,502 | |
0,425 | 0,411 | 0,390 | 0,372 | 0,376 |
.
As, (6.13), S (. 6),
(6.14) |
6
, % | |
: | |
a) ( ) | 0,10 |
) | 0,15 |
) | 0,20 |
) | 0,25 |
: , (%) 0,10 0,25 |
S' :
As, min
(6.15) |
As, min -
(6.16) |
As, min , (6.12) (, ),
(6.17) |
, (6.17), .
. .
: b =400 , h =400 ; a=a' =45 ; 30 (Eb =32500 , Rb =17 ); 400 (Rs = Rs' = 355 ); : : N = 1532,98 , M =101,94 ͷ, Nl =1319,98 , Ml = 86,19 ͷ; l =6,0 .
|
|
, ηv = 1,0 . h 0 = h a = 400 45 =355 (. 6.1).
. 6.1. |
, , :
2,
αR =0,39 ξR =0,531 6.1;
=221 .
4 Ø 32 A's =3217 2.
2.
4 Ø 28 As =2463 2.
μ =3070100/4002 =1,92%. b × h = 400×600 40.