, , : .
1. ( 100 220 ) (. 2, ), , l= 3 , α = 30, l = 1,5 , g12 = 1 /2, s12 = 2 /2.
. 1 2
q 12 = g12 + s12 = 1+2 =3 /2
( ) (. 2, ):
q 1 . = q 12 l = 3* 1,5 = 4,5 /.
q 1 . q α 1 . (. 2, ):
q ┴1 . = q α 1 . cos α = 4,5 s 30 = 4,5 0,866 = 3,9 /;
q ║1 . = q α 1 . sin α = 4,5 sin30 = 4,5 0,5 = 2,25 /.
q α 1 . . ( , ), q α 1 . (. 2, ). , q α 1 ..
q ┴1 . q ║1 , (. 2, ):
= (q ┴1 * l2)/ 8 = 4,39 ͕ = 439 ͕ ;
= (q ║1 ** l2)/ 8 = 2,53 = 253 .
σ (i) = Mx/Wx + My/Wy ≤ [σ]
y
Wx = bh2 /6= 10*22 2 / 6= 807 3;
Wy = b2 h/6 = 22 * 10 2 /6 = 367 3.
[σ] = 14 = = 1,4 /2.
:
439 / 807 3 + 253 / 367 3 ≤ 14 /2,
1,23 /2 < 1,4 2.
, .. .
. 2. 1:
; , ; ;
2. (), h=2b, .3. .
3. 2.
.
F , X Y:
F = F sinα = F * sin30 = 200 0.5 = 100 :
|
|
F = F cos α= F s30 = 200 * 0.866 = 173.2 ;
, :
= F *l = 100 1 = 100 :
= Fy *l =173.2 1 = 173,2 .
,
F .. α = 30.
- tg β= tg α * Jx/Jy = (bh3 / (b3h) tg α = (h/b)2 tg α =22 *0.5774 = 2.3096
( h/b = 2), β = 66.58. .
1 2 : 1 ,
2 -.
: σ (i) = Mx/Wx + My/Wy = 1/Wx (Mx + WxMy/Wy)= 1/Wx (Mx +k My)
Wx/Wy = (bh2 /6) / (b2 h/6) = h/ b = 2.
σ
[σ] = 130, = 2 105 :
σ = 37,32/ W x =[σ]=130,
: Wx = 287076,92 3=287c3.
h/b = 2 Wx = bh2 /6 = 2b3/3
.
b= 3√3Wx/2 =3√3* 287/2 = 7,55 .
h = 2b = 2 *7,55 = 15,1.
3..
Fy = 173,2
δy. F =100 δx. δx δy :
δx = Fxl3 /3EJy; δy = Fyl3 /3EJx.
Jx = h3b/12 = 15.13 *7.55/12 = 2166,19 4
J = hb3/12 = 15.1 *7.553/12 = 541,55 4
δx = Fxl3 /3EJy =(100*103 *103)/ 2*3*105 * 541,55 * 104 = 0,00008
δ = Fl3 /3EJ = (172,3 *103* 103)/3*2*105 * 2166,19 * 104= 0,0000533
δ =√ δx2 + δ2=√0,000082+0,00005332=0,000096
: tg φ = δx/ δ
.
, . . [σ] = 140. = 2 105 . 1.
4. .
- | F, | l, | α, | - | F, | l, | α, | ||
2,5 | 2,5 | ||||||||
2,5 | 2,5 | ||||||||
2,5 | 2,5 | ||||||||
2,5 | 2,5 | ||||||||
2,5 | 2,5 | ||||||||
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1. .
2. F X .
3. My, Mx.
4. ( tg β= tg α * Jx/Jy,).
5. .
6. .
7. .
8. δx δy δ.
9. .
10. tg φ.
1. - .
2. . ?
3. ?
4. , . .
5. , , .
6. .