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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

αmR

.

 

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



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