, . (. 5.4, ) , , ( 1). , , . , , , , . (. 5.4, ) Rsc ( 2).
1 ξ=/h0≤ξR, 2 ξ>ξR. ξR (4.5).
● 1. , : III - ; σs=Rs; σ'sc=Rsc, σb=Rb; ; .
, 5 (. 5.4, ):
= 0 + h/2.
, :
. 5.4. (, ) () ; ()
, . (5.4)
x≤xR = ξRh0 ( 1), (5.3) . >R 2.
(5.3) (5.4) : , As, A′s. ( ) , x=xR. (5.3)
(5.4)
30 , αR=0,4, ξR = 0,55.
A′s>0 A′s≥μminbh0. A′s<0, . , A′s=μ′minbh0. (5.3) ,
, . .
|
|
ξ, (5.4)
- As A′s .
As=A′s Rs = Rsc ( A-II...A-III) x=N/(Rbb). (5.3)
● 2 (ξ=x/h0>ξR). , , , , σs<Rs.
(5.3), (. 5.4, )
σs 30 A-I, A-II, A-III [7]
, ξ=ξR; σs=Rs; ξ=l ( ) σs = Rs=Rsc.
x>ξRh0 (5.3), =ξh0, ξ 30
an=N/(Rbbh0), as = RsAs/(Rbbh0).
x [. (5.6)].
■ . , . , (. 5.4, ). , . . . ( ), f e0 η. l0/i>14 ( l0/h>4)
0 , ; Ncr [1], , , , , .
l0/i<14 (l0/h<4) , η = l. η≤2,5. η>2,5 .