, . :
)
=-(W-W')/2=-(3,11-2,34)/2=-0,385
) , :
=(-3/16)H(- ')=(-3/16)3,8(1,73-1,30)=-0,306
) :
=(-9/8)(/); =- , =(h/2)+(h/2)=(120/2)+(16,2/2)=
=68,1 =0,681
=-11,94∙0,681=-8,13 ∙
=(9/8)(8,13/3,8)=-2,4
.
:
=[(W- - ) H +(* H 2)/2]+∙ H -=[(3,11+0,385+ 0,306)∙3,8+(1,73∙3,82/2)]∙0,9-2,4∙3,8+8,13=24,14 ∙
=[(W'- - ) H +('* H 2)/2]+∙ H - =[(2,34+0,385+ 0,306)∙3,8+(1,3∙3,82/2)]∙0,9-2,4∙3,8+8,13=17,82 ∙
:
N= pq+ + + ∙0,9=23,5+6,0192+11,94+97,2∙0,9=128,94
:
Q=(W--+ H )+=(3,11+0,385+0,306+1,73∙3,8)∙0,9+2,4=
=10,26
Q=(W'--+'H )+(-)=(2,34+0,385+0,306+1,3∙3,8)∙0,9-2,4= =4,77
=0,9-
:
=24,14 ∙
Q =10,26
N=128,94
h=18/15=1,2 , b = h/5=1,2/5=0,24
.
F= h b =1,20,24=0,288 2=2880 2
I=(h3 b )/12=(1,230,24)/12=345,610-4 4=3456000 4
W=(h2 b )/6=(1,220,24)/6=57,610-3=57600 3
- ( )
σ =(N/F)+(∙R)/(ξWRu)≤ R,
R=130 /2 Ru=130 /2
ξ=1-(N/(φ∙F∙R))- 1 0,
φ=3000/λ2--
λ=l/(0,289 h)-
l=0,8H =0,83,8=3,04
λ=3,04/(0,2891,2)=8,77; φ=3000/8,772=39
ξ=1-(128,94/(39∙0,288∙13*103))=0,99
σ =((128,94*103/0,288)+ (24,14*103*13*103/(0,990,057613*106))=
0,448*106 <13*106
( ):
σ =(N/Fφ)≤R
φ=1-0,8(λ/100)2, λ≤70;
φ=3000/ λ2, λ>70
λ =l/r; r= √(I/F)=√(138240/2880)=6,9
I= (h b 3)/12=(120∙243)/12=138240 4
λ =304/6,9=44,05<70=> φ=1-0,8(44,05/100)2=0,86-.
σ =(128,94/0,288*0,86)=0,52 ≤13
|
|
:
τ=QS/ (ξI∙b)≤ R=24 /2
S=(h2 b )/8=43200 3
b =0,6∙b=0,6∙24=14,4
τ=(10,26∙0,043)/(0,99∙0,034∙0,14)=0,09 <2,4
18 , -
. . 3 .
.
N=pq+ + =23,5+6,0192+11,94=41,45
=[(W- -) H +((* H 2)/2)+∙ H - ]∙1/ξ=
=[(3,11-0,385-0,306)∙3,8+(1,73∙3,82/2)+2,4∙3,8-8,13]1/0.99=22,9 ∙
:
σmax,min=-N/(hb )6/(h2b ), h= h+6δ=1,2+6∙0,042=1,452
σmax,min=-41,45/(0,24∙1,452) 6∙22,9/(0,24∙1,4522)=[-118,9271,5]=
=[152,6;-390,4]
= (σmax/(σmax+ σmin))∙ h=((152,6/(152,6+390,4))∙1,452=0,4
= (h/2)-(/3)=(1,452/2)-(0,4/3)=0,5
= h- /3-S, S=3 δ=3∙0,042=0,126 => =1,452-(0,4/3)-0,126=1,19
:
Z= (- N∙)/=(22,9-41,45∙0,5)/1,19=1,9
: F=Z/(n∙R),
n- ,
R-
R=1400 /2
F=1,9/(214)=0,2 2
F d=12 .
, , b + d=240+12=252 :
=Z/4∙(l-b /2)=1,9/4(0,252-0,24/2)=0,1 *
I, Z:
=(h-h)/2=(1,452-1,2)/2=0,126 =12,6
/δ=12,6/4,2=3 .(- )
3 δ=342=126 ; 130 (-8486-66): ∟12510, Z=3,45 , I=360 4
, :
τ=Z/ h∙b ≤ R, h=0,98 -
b =0,6 b=0,624=14,4
R-
R=R/(1+(β∙h/))=2,4(1+0,125*(0,98/3,8))=2,3
β=0,125 .
=3,8
τ=1,9/(0,980,144)=13,46 ≤2300
:
σm=((δ- Z))/I≤R, R=2100 /2- .
δ=125 -
σm=(0,1(0,125-0,00345))/360*10-8≤2100, 3,3 ≤2*105 -
- . , .
|
|
b= , Q= - . =2,4 .
b= .