7.69 ≤ r (7.55) :
) :
N ≤ φ (Rb Ab + Rsc A's + Rpc A'p); | (7.31) |
(7.32) |
) :
N ≤ Rb Ab + Rsc A's - σpc 1 A'p; | (7.33) |
(7.34) |
(7.31) - (7.34):
N - ( );
φ - , 7.55;
Rb - , 7.6;
b - ; 3 %, b (b - A ' s - ' );
Rsc, Rpc - , 7.38;
σpc - , 7.60, , ;
σpc 1 - ' , 7.60, ;
μsc = A's / Ab;
σb = N / Ab;
's, 'p - ;
n 1 - , 7.48.
7.70 , > r > h'f ξ ≤ ξ y ( 7.2 7.4) ,
(7.35) |
0
0 = + (η - 1), | (7.36) |
N - ;
η - , 7.54;
- N ;
- N ( 7.52);
σ - , , , 7.60.
(7.35) b'f = b.
N + RbAp + RsAs - RscA's σ pcA'p = Rbbx + Rb (b'f - b) h'f | (7.37) |
(7.37) N .
. .
7.60. > 2 a's, < 2 a's, ,
|
|
Ne0 ≤ (Rp Ap + Rs As + N) (h 0 - a's). | (7.38) |
(7.100) Rb,mc 1, .
7.4 - , ,
7.71 r 1 r 2 r 1/ r 2 ≥ 0,5 , ( 6), ,
(7.39) |
ξcir :
) 0,15 < ξcir < 0,60
(7.40) |
) ξcir ≤ 0,15
(7.41) |
(7.42) |
) ξcir ≥ 0,6
(7.43) |
,
(7.44) |
(7.39) - (7.44):
b - ;
As,tot - ;
rm = (r 1 + r 2)/2, | (7.45) |
r s - , .
e 0 7.52 7.54 7.70.
7.72 7.69, 7.70. , ( ), Rb Rb,red. l 0/ ief : - 55, - 35 ( ief - , ).
Rb,red :
)
Rb,red = Rb + φμs,xy Rs, | (7.46) |
Rs - ;
(7.47) |
(7.46) (7.47):
nx, Asx, l - , ( );
n, Asy, ly - , ;
f - , ( );
s - ( ); , s 7 ;
φ - ,
(7.48) |
(7.49) |
(7.49) Rs Rb , μ = μs,xy.
1,5 ;
)
(7.50) |
Rs - ;
|
|
- ( );
μ - ,
(7.51) |
As,cir - ;
def - ;
s - .
7.54, , . Ncr, (7.9), φ1 = 0,25 + 0,05 l 0/ cef ≤ 1 ( cef ), δ (7.12) 0,01(l 0/ cef)φ2, φ2 = (0,1 l 0/ ef - 1) ≤ 1. , , f Rb,red, , b Rb ( ). , 7.153.
7.73 , . 7.69, 7.70 ( γf = 1), Rb Rs Rbn Rsn , Rsc,ser, 400 .