6.1. 75 % - - 50 .
6.2. .
6.3. , , . .
6.4. , .
, , (, , ), , .
6.5. (, , ). , - - ; , - , .
6.6. , . , , .
6.7. ( ); , . .
6.8. . . .
6.9. II-25-80.
, ; .
P = 1,2 1 .
6.10. - . :
, ;
.
|
|
, , .
. 25.
) ; )
, , . .
. 1.
6.11. . i ≤ 1:20 . .
18 . 1/15 . II-25-80, . 5.5 5.7.
. 25.
6.12. II-25-80, . 4.9. x = lh 0/(2 h),
l - ;
h 0 - ; ;
h - .
hx = h 0 + ix, (42)
i - .
22
K 0 | |
(A + m 1)/[1 + γ(A + m 1)] (0 ≤ K 0 ≤ α) (A - 2γα m 1)/(1 - γ A) (α ≤ K 0 ≤ α + α) { A - m 2 - 2γ[α(m 1 + m 2) + α m 2]}/[1 + γ(A - m 2) (α + α ≤ K 0 ≤ 0,5) | |
1 γ m ≤ 2, m (1 + γα)/(0,5 m γ - 1) γ m > 2 α ≤ K 0 ≤ 1 |
6.13. , ,
x 0 = K 0 l, (43)
K 0 - , . 22.
. 22 mi, γ A
mi = Pi /(ql); (0 ≤ i ≤ 4);
γ = 2 (h / h 0 - 1);
A = 0,5 + m 2 - α(m 1 + m 2 - m 3 - m 4) - α(m 2 - m 3).
. 22 K 0 , ; , .
:
- ;
- ;
(. . 22):
- u = (h 0/ h) l,
- u = 0.
6.14. II-25-80 .
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6.15. h / l ≥ 1/10 σα. x = 0,9 h 0 x = 1,1 h 0 .
x = 0,8 h 0 ¸ 1,2 h 0; Y = 0,1 h 0 ;
x = h 0 ¸ 1,4 h 0; Y = 0 ¸ 0,15 h 0 ; .
σα = 0,5[σ x + σ y + ] ≤ R α, (44)
σ x - ;
σ y = σ q + σ - ;
σ q = q /(2 b) - q ;
σ = -4 P cos4 (arctg (2 x / hx))/(π bhx) - ;
τ xy - II-25-80, . 4.10, -
τ xy = 3(Qx - iMx / hx)/(2 bhx),
. 26. () 1, 2 3
. 27.
) ; )
i - ;
α - , ; :
σ x - σ y ≥ 0
α = 0,5arctg [2τ xy /(σ x - σ y)];
σ x - σ y < 0
α = 0,5{180 + arctg [2τ xy /(σ x - σ y)]};
R α - α; . 26;
x - ;
y - ; ;
b - ;
h 0, hx - x;
Qx, Mx, Jx - , x.
6.16. (. 27) 10 - 25 %. .
.
. b l 1 = (0,1 - 0,3) l. i 2, i 1 ( 7 - 10 %). γ φ r 0. , %,
γ = arctg 0,01 i 1,
r 0 = l 1(2sin φ).
φ = arctg 0,01 i 2.
m II-25-80, . 3.2, . r / a ≥ 500, m = 1 .
(. . 27)
h =
b ≥ 12 , m ≈ 0,85 K = 1,3, K - , .
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h 0 = h 1 - 0,5 l (tg γ - tg φ),
h 1 = h - 0,5 l 1tg φ + r 0(1 - cos φ).
x = lh 0/(2 h 1).
, .
, -
hx = h - r 0[cos (γ - φ x)/cos γ - 1],
φ x = arcsin [(0,5 l - x)/cos γ].
6.17. , , :
σ r = KrM / W ≤ R 90,
σ = K M / W ≤ R ,
M W - ;
Kr K - , γ; . 28, 29 h / r, h / l γ, r = r 0 + 0,5 h - .
, , , , , .
6.18. II-25-80, (18).
. 28. K
--------- ; - - - - - ; 1 - h / r = 1/16; 2 - h / r = 1/13; 3 - h / r = 1/10
. 29. K
6.19. II-25-80, . 4.33,
Δ l = f (tg γ + tg φ) ≤ 4 .
6.20. .
σ = (M / W) K ≤ R ,
K = 1 + 0,5 h / r.
, h / l,
σ r = (M / W) Kr ≤ R 90,
Kr = 0,25 h / r - 0,083(h / l - 0,034).
Kr = 0,25 h / r.
6.21. 18 (. . 1). . 25 %, - 5 - 10 % . 12 . .
33 . ( II-25-80, . 6.20).
. II-25-80, . 5.6 5.8.
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, . .
6.22. II-25-80 . II-25-80, . 11, 20 %.
( )
x = , γ = h' 0/(li);
h' 0 - ;
l - ;
i - .
hx (42).
6.23. , II-25-80, . 4.28 4.30. R α m = 0,8, , , . : ; - . .
6.24. , , - 6 - 21 II-25-80. . 5.18 5.21 :
;
0,4 l .
n :
n ≥ 1,2 M S (I T), (45)
- -
n ≥ 1,2 M S /(I T) + KN / T, (46)
M - , (29) II-25-80 N, N × e;
T - ;
S , I - ;
K - , N.
N: K = 0; ( ) K = 0,2; K = 0,2; K = 0,4. N 1/3 .
.
1/200 4 16 .
6.25. II-25-80, . 4.9. 4.33 KW K - . 13 . , , KW K :
KW = 1/[1 + (n - 1)δ/δ],
K = 1/[1 + (n 2 - 1)δ/δ],
n - ;
δ - , , . 21;
δ - M = M / n; M - ; δ = nl /(300 K θ); l - , ; K θ - , ; K θ = 4; K θ = 3, K θ = 2.
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1. 11,75 , 1,5 , 1:20 (. 30). .
: q = 17 /; q = 13 /.
: 33 2- 3- . 2- 0,15 ( II-25-80, . 6.19).
. 30.
: 35 , 60 75 %. m = 1 ( II-25-80, . 5).
b = 14 , h = 102,3 , .. l /11,5 > l /15, h 0 = 72,6 .
II-25-80 (17)
x = lh 0/(2 h ) = 1175×72,6/(2×102,3) = 417 ;
h 1 = h 0 + ix = 72,6 + 417×0,05 = 93,5 ;
Mx = q (l - x) x /2 = 17(11,75 - 4,17)4,17/2 = 268,7 ×.
2- II-25-80, . 3.1 3.2, m , m , m γ n 384-76.
R = R = 15 m m m /γ n = 15×1×0,86×1/0,95 = 13,6 .
σ x = Mx / Wx = 268,7×106/20,4×106 = 13,2 < 13,6 ,
Wx = bh 2 x /6 = 140×9352/6 = 20,4×106 3 -
.
[ II-25-80 (18)].
Q = ql /2 = 17×11,75/2 = 99,9 ;
2-
R = 1,5 m m /γ n = 1,5×1×1/0,95 = 1,58 ;
QS /(I b ) = 99,9×103×3/(2×726×140) = 1,48 < 1,58 .
σ = Q /(cb) = 99,9×103/(250×140) = 2,85 < R .90/γ n = 3/0,95 = 3,2 .
2×1,5 , , l = 300 < 140 b 2/(hm ) = 140×142/(102,3×0,85) = 315 (. . 4.25), .
II-25-80, . 4.32 4.33.
= 0,15 + 0,85 h 0/ h = 0,15 + 0,85×72,6/102,3 = 0,753;
c = 15,4 + 3,8 h 0/ h = 15,4 + 3,8×72,6/102,3 = 18,1;
f = 5× q l 4/(384 El) = 5×13×11,754×12×1012/(384×10×140×1,0233×1012) = 25,7 ;
f = (f / )[1 + (h / l)2] = (25,7/0,753)[1 + 18,1(1,023×103/11,75×103)2 = 38,8 f / l = 1/302 < 1/300, .. .
2. , . 31.
q = 14,8 /, q = 1,3 /, 10 .
. 6.13.
d = u / l = 150/1800 = 0,083; α = u / l = 600/1800 = 0,33;