, (. 4), l0 £ 20h
N £ j [hb(R b A + RscAs) + hrcr(Rb,rcrArcr+ Rsc,rcrAs,rcr)],
N ; hb , 0,9 h<200 I h ≥ 200 ; φ ; hrcr , : 0,9 ; 0,8 ;
Rb , ; Rb,rcr ; Rsc, Rsc,rcr ; , Arc ; As, As,
N £ j hb(R* b A + RscAs),
R* b ; N, hb, φ, Rsc, As .
:
R* b = R b(1+0,5),
R b R bt , ; σr , - ,
σr = (2nf Pf)/b,
nf ; b ; Pf 1 .
(nf) (Pf) - ,
nf Pf ≥ R bt b
.
:
bh=0,3x0,3 B15; Rb=8,5 ;
4Ǿ12II; As=4,52 2; Rsc=280 ;
H3=3,6 .
=0.
- N=Nd= 1200 .
δ=0,06 , (.5)
b1=h1=b+28=0,3+2-0,006=0,42 .
,
As1,=0,009(h1*b1 h*b)=0,009(0,42-0,42-0,3*0,3)=7,8*10-42=7,82.
6Ǿ14AII ( A's1 = 7,69 2)
.
l0 /h = 3,6/0,3 = 12 < 20 =0, - N≤ φ(RbA + RscA's); φ = φb +2(φsb φb) α s. RscA's280*4,52*10-4 α s = RbA = 8,5 -0,3 0,3 = 0.165 .3 φb =0,8; φsb =0,89; φ=0,86+2(0,89-0,86)0,165=0,97. N>0,87(8,5*103*0,09+280*103* 4,52*10-4) = 776 , 1200>776 . 5 |
, . :
|
|
α = RSC(A'S + A's1) = 280(4,52 + 7,69) * 10-4
Rb *A 8,5*0,42* 0,42 = 0,23
l0 / h = 3,6/0,42 = 8,57; φb = 0,905; φsb = 0,905;
φ = 0,905+2(0,905-0,905)0,23=0,905;
N < 0,905*8,5*103*0,42*0,42+280*103*(4,52+7,69)*104=1667;
1200<1667 .
. : 1667 - 776 = 891 .
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