4.17. II-25-80 - . , , . . . , .
4.18. ( ) / R . = 300; E / R . = 200 E / G = 20.
: Jy = b 3 h /12 Jd ≈ b 3 h /3. ,
γ = EJy /(GJd) = 20/4 = 5.
4.19. , , :
N = π3 EJy / l 2 = φ R . F ; (23)
, :
M = π = φ R . W. (24)
(23) , φ = π2 EJy /(l 2 R . F) ≈ 3000/λ2,
(24)
φ M = π /(lR . W) = 6π b 3 hE /(6 bh 2 lR .) = 140 b 2/(lh),
N = KNN M = KMM , KN KM - , , (23) (24).
φ N = KN φ φ M = KM φ M,
φ M φ N - .
4.20. KN KM . :
KN = K NK N; KM = K K MK M,
K N - ;
K M - ; K N K M - . . 4.4.
. , . K N = 1 K M = 1.
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4.21. (24) (34) II-25-80 K N K M . , N M ( .. ),
M + Nh /3 = EJy [(h 2/4)(π n / l)2 + h / r 0 + l 2/(r 20π2 n 2)] + GJd (h / r 0 + 1), (25)
l - ; n - ;
r 0- .
(25)
M + AN = D, (26)
M = 0, AN = D N = D / A, N = 0 M = D.
(26) M / D + AN / D = 1,
N / N + M / M = 1. (27)
N M - N M .
EJy (GJd) = 5 n = 1 (25),
N = (3 GJd / h 2)[1 + 12,5(h / l)2 + 10α(h / l)], (28)
M = (GJd / h)[1 + 12,5(h / l)2 + 10α(h / l)], (29)
α = l / r 0.
, KN = K N = N / N KM = K M = M / M , (23), (24), (28), (29) N , M , N , M (24) (34) II-25-80.
, , . , , . , , .
4.22. - () , (28) (29).
. II-25-80 , , .
= 0,06(l / h)2(1 + 12,5 h 2/ l 2); (30)
= 0,142(l / h)(1 + 12,5 h 2/ l 2). (31)
K N K M ( ) (30) (31). :
, (32)
- m; = 0 m = 0 = 1 m → ∞.
= m 2/(m 2 + 1). (33)
(32) (30), (31), (33), :
(34)
II-25-80 (34) (24) α = 0. , m , .
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4.23. K (. . 4.20), . . 2 . 4 II-25-80.
. 18 K , .
- K , .
4.24. K N K M. . K N = 1 K M = 1.
, , , . 1 2 . 4 II-25-80.
18
K | ||
l | M | |
1,13 - 0,13α 0 ≤ α ≤ 1 | 1,13 - 0,13α 0 ≤ α ≤ 1 | |
1,13 α × (0,12 + 0,02α) -2 ≤ α ≤ 0 | 1,13 α × (0,12 + 0,02α) -2 ≤ α ≤ 0 | |
1,35 - 0,35α 0 ≤ α ≤ 1 | 1,35 - 0,35α 0 ≤ α ≤ 1 | |
1,35 - 0,35α -1 ≤ α ≤ 0 | 4/(3 + α) -1 ≤ α ≤ 0 | |
1,35 + 1,45(c / l )2 | 1,35 + 0,3(c / l ) | |
1,75 - 0,75α 0 ≤ α ≤ 1 | 3/(2 + α) 0 ≤ α ≤ 1 | |
1,75 - 0,75α -1 ≤ α ≤ 0 | 3/(2 + α) -2 < α ≤ 0 | |
2,54 | 2,32 | |
1,13 α × (1,4 + 1,27α) -1 ≤ α ≤ 0 | 1,13 α × (0,57 + 0,2α) -1 ≤ α ≤ 0 |
4.25. (23) II-25-80 m . 7 .
4.26.
N / + [ M / ] n ≤ 1, (35)
N, M - ;
, - ;
N = φ R F = φ R W.
(35) n = 1 , (N = const; M = const) n = 2 , .
, φ φ . φ > 1 φ > 1, . , (33) II-25-80 φ φ.
φ
φ = 3000/λ2.
- N ( II-25-80, . 4.2, 4.3), λ y < 70 σ > σ.
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