4.27. , . 4.33 II-25-80, . , , . , II-25-80 . 4.34 EJ 0,7, , II-25-80, . 4.33.
4.28. r h.
, , . , , , - .
4.29. , r / h > 7 (. 8), (21) II-25-80
σ ri = (σ0 + σ i) hi /(2 ri) ≤ R 90,
, σ i = 0, hi = h /2, ri = r, σ0 = 6 M /(bh 2), (21)
σ r = 3 M /(2 rbh) ≤ R 90 (R 90). (36)
. 8.
r / h ≤ 7 , . (36)
σ r = (M / Fz 0)[ r 0/ r 1 - 1 - ln (r 0/ r 1)] ≤ R 90; (37)
z 0 = J /(Fr); r 0 = r - z 0; r 1 = r - h /2;
(. . 11) F = bh; z 0 = h 2/(12 r);
σθ i
σθ i = M (r 0 - ri)/(Fz 0 ri),
r - ;
r 0 - ;
ri - .
4.30. . , .
4.31. (. 9) , , , . , ,
τ = σ r (b - Σδ)/(h n ) ≤ R .,
σ r = (M / F z 0)[ r 0 h /(r 1 r ) - ln (r / r 1)];
|
|
b - ;
Σδ - ;
h - ;
n - ;
R . = R ./[1 + β1 h / e ];
e - (. . 9);
β1 - , (β1 = 0,15);
R . - .
. 9.
4.32.
σ r = M /(F . z 0)[ r 0/ r 1 - 1 - ln (r 0/ r 1)] + σ r (b - Σδ)/Σδ ≤ R .α, (38)
R .α - ( ) .