5
, , .
≤ ,
- ,
- , .
1 2.
M = Nszb = RsAszb = RsAs(h0 0,5x)
M = Nbzb = RbAbzb = Rbbx(h0 0,5x)
.
ΣXi = 0
Rb b x = Rs As.
x = Rs As / Rb b
xR , (ξR=xR/h0).
. ξR
ξR
εs,el :
εs,el = (Rs- σsp)/Es,
εs,el = (Rs + 400 - σsp)/Es,
σsp- , γsp= 0,9,
εb,2
εb,2 = 0,0035, Rb, Es, σsp .
ξ = / h0 ≤ ξR Rs
γs3 = 1,25 0,25 ξ/ ξ R ≤ 1,1.
ξ/ ξ R < 0,6 γs3 = 1,1.
M = Rbbx(h0 0,5x).
h0/h0 h0
= Rbbxh02(1 0,5x/h0)/h0.
, ξ = /h0,
= Rbbh02 ξ(1-0,5 ξ).
ξ(1-0,5ξ) αm,
M = αmRbbh02.
αm = /Rbbh02.
αm = ξ(1-0,5ξ) 0,5ξ2-2ξ+2αm = 0.
D = 2√(1+2αm).
ξ1,2= (2 D)/2 = 1 √(1-2αm).
-.
|
|
.
RsAsh0(1 0,5ξ) = Rbbh02 ξ(1-0,5ξ)
As = ξ Rb bh0 /Rs
αm > αR . , .
ξ = / h0 ≤ ξR
, Q, N.
αm.
αm= 0= / Rbbh02
αm<αR
.
μmin.
μmin .
. μmin = 0,03Rb/Rs. μmin .
μmax ,
μmax% = ξR Rb /Rs 100%. 3%.
μ % = 0,3 - 0,6 %.. ξ = 0,1- 0,15
μ % = 1- 2% ξ =0,3 - 0,4