6
( ), , , .
, ,
.
x ≤ h'f.
, , = h'f.
M ≤ Mf = Rbb'f h'f (h0 0,5h'f)
RsAs ≤ Rbb'f h'f
, b'f × h, .. .
M > Mf = Rbb'f h'f (h0 0,5h'f)
RsAs > Rbb'f h'f
. , .
RsAs = Rbbx + Rbh'f (b'f b)
M ≤ Rbbx(h0-0,5x) +Rb(b'f b)h'f(h0 0,5h'f)
6 ()
()
, , ,., .
ξ >ξR > R.
, , , , .
1, .
∑1 = 0
M ≤ Rbbx (ho0,5x) + RsA`s(ho a`)
, .
Rbbx = RsA-RsA`s
, = R ξR αR.
30 240, 300, 400 ξ=ξR =R
|
|
M ≤ RbbxR(ho 0,5xR) + RsA`s(ho a`)
RbbxR = RSAs - RscA`s
Mb,max = αRRbbho2 ,
's = - Mb,max
240, 300, 400 Rs= Rs,
As=(RbbxR/Rs) + A`s
ho,
As = (ξ RRbbh0 /Rs) + A`s
, αR = 0,4; ξ R = 0,55
As = (0,55Rbbh0 / Rs) +A`s , x > 2`. x ≤ 2`, zb = za .
M ≤ RsAs(ho a`)
.
, , :
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500 ?
10d.
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