.
:
ΣmomAFi =0
F*2-g×2*1-M+4*Rb=0
R = (40*2+20+50)/4=-2.5 ()
ΣmomFi =0
F*6-g*5-M-RA *4=0
RA =(2*40-100-50)/4=22.5 ()
( y).
:
ΣFi =0
RA + Rb+ g *2-F=0
-2.5+22.5+20-40=0
0=0 => , .
.
: , . , .
. 0≤ u1≤ 2
Q1 =-(F-qu1 )=-40+10 u1- .
u1 | ||
QY1 | -40 | -20 |
Mx1 = - (F * u1 - q u1* u1 /2) = q * u12 /2 F * u1-
:
Mx1 =5* u12 40* u1
Mx1 ٰ = 10* u1 40
10 u1 - 40 = 0
u1 = 4 ( ) ( )
M1 ''= 10 =>
u1 | ||
Mx1 | -60 |
. 0≤ u2 ≤ 2
Q2 = - (RB) = - RB =2.5H .
Mx2 = - (-RB*u2 ) = RB* u2 = -2.5* u2 - .
u2 | ||
Mx2 | -5 |
. 0≤ u3 ≤ 2
Q3 = - (RB)= - RB = 2,5 .
Mx3 = - (- RB (u3 +2)+ ) = RB * u3 + RB *2 = -2,5 *u3 5 50 = =-2,5 *u3 -55
U3 | ||
Mx3 | -55 | -60 |
, , , Q Mx.
... Q Mx. (. .1.)
.
, Mx max , Mx=60*106 (*)
(27) Wx = 371 (3)
Wx < Wx .
Wx 27 , .
.
5%, 27.
, 5% .
3. . ( - )
, Qy max , Qy. Qy max = 40*103 ()
|
|
, 27: .2.
S max ( ). S max = 210*103 ()
I- . I = 5010*104 (4)
b- (. .2). b= 6 ()
=27,9 ()
, τmax [τ] =100 (), 27 .
, b, I, S max .