: F = p×A0 = 333,64×(3,0+2,6)×0,2/2 = 186,84 .
: F £ Rbt×bm×h01; 186,84 < 0,75×2350×250 =440625 =440,6;
: bm = (2600 + 2100)/2 = 2350.
.
3. .
2.3 .
hcf-dp=600-650<0,5(lcf-lc)=0,5(900-400)=250,
= 2 (bc +lc)dc= 2(400+400)600 = 960000 2
α = (1-0.4 RbtAc/N1) = (1-0,4.0,75.960000/ 3002720) = 0,9> 0,85, α =0,9
0 = ((3000+2100)/2)450 = 1147500 2
bm = (3000+500)/2 = 1750 2
Nc = αN = 0,93002,72 = 2702,45 < blRbt bmhop/A0=300030000,751750800/1147500 = 8235294H = 8235,3
N .
4. .
2.4. Nc
, .
2.5.
: b/l = 3,0/3,0 = 1,0 > 0,5 .
2.6.
.
2.7.
1 1 ( ):
h1 = 300, h01 = 250, b = 3,0, 1 = 450.
1-1 = 0,5×p×b×12 = 0,5×333,64×3×0,452 = 101,34 ×;
am = 1-1/(Rb×b×h012) = 101340000/(8,5×3000×2502) = 0,064 ξ1 = 0,066;
S1 = 1-1/(RS×(1-0,5*ξ1)×h01) = 101340000/(355×(1-0,5*0,066)×250) =1180,83 2.
2 2 ( ):
h2 = 600, h02 = 550, b =3,0 , b1 = 2,1, 2 = 750.
2-2 = 0,5×p×b×22 = 0,5×333,64×3,0×0,752 = 281,51 ×;
am = 2-2/(Rb×b1×h022) = 281510000/(8,5×2100×5502) = 0,052 ξ2 =0,053;
S2 = 2-2/(RS×(1-0,5*ξ2)×h02) = 281510000/(355×(1-0,5*0,053)×550) =1481,04 2.
3 3 ( ):
h3 = 900, h03 = 850, b = 3,0, b2 = 1,5, 3 = 1050.
3-3 = 0,5×p×b×32 = 0,5×333,64×3,0×1,052 = 551,76 ×;
am = 3-3/(Rb×b2×h032) = 551760000/(8,5×1500×8502) = 0,06 ξ3 = 0,062;
S2 = 3-3/(RS×(1-0,5*ξ3)×h03) = 551760000/(355×(1-0,5*0,062)×850) = 1887,03 2.
5. .
b , .
|
|
, 1887,03 2 2,92,9 16 Æ14 400 AS = 2462 2 (+30%).
:
m1% = AS1×100/(b×h01) =2462×100/(3000×250) = 0, 328% > m%min = 0,05%;
m2% = AS2×100/(b1×h02) =2462×100/(2100×550) = 0,213%> m%min = 0,05%;
m3% = AS3×100/(b2×h03) =2462×100/(1500×850) = 0, 193%> m%min = 0,05%;
2.8.
1050´1050.
6. .
= lcf /30=900/30=30 .
1 1:
N1-1 = N Nc + G ef = 3002,72 2702,45+ 1,1×25×0,9×0,9×0,6 =313,64 ;
1-1 = N1-1× = 313,64×0,03 = 9,41 × N1-1 01-1 = = 0,03.
N1-2 = (1 a)×N2 + G ef = (1 0,9)× 2811,12+13,365 =294,48;
1-2 = 2 + Q2×hcf = 18,58+ 9,23×0,6 = 24,12 ×;
01-2 = 1-2/ N1-2 + = 24,12/294,48 + 0,03 = 0,112 < 0,45.lcf = 0,45×0,9 = 0,405.
, . , e0,1-2 e0,1-1.
7. () () .
:
)
b N1-2 .
)
01-2 = 112, Icf = 0,4.0,93/12 + 2.(0,5.0,23/12 + 0,5.0,2.0,352) = 0,04954;
= 0,92 0,52 = 0,562; i = = = 0,297;
W = Icf/0,5lcf = 0,0495/0,5*0,9 = 0,113;
r = i2/0,5lcf = 0,2972/0,5*0,9 = 0,196 =196 > 01-2 = 112, . .