( )
: hb =1200 ; bf = 300 ; tf = 20 ; tw = 10 ;
; RA = 400 ; 285.
, , (hk = 500 ).
. 19
1. Mu.
Jx = Jw + 2 Jf = tw∙ hw 3 / 12 + 2∙ (bf∙ tf 3 / 12 + bf∙ tf∙ h0 2 / 22 ) =
= 1∙ 1163 / 12 + 2∙ [30∙ 23 / 12 + 30∙ 2∙ (118 / 2)2] = 339183 4;
Wx = 2 Jx / hb = 2∙ 339183 / 120 = 5653 3;
Mu = Ry∙ γc∙ Wx = 26 ∙ 1,0 ∙ 5653 = 146979 ∙ .
2. :
NF = Mu / h0 = 146979 / (120 2) = 1246 .
3. , :
βf∙ Rwf γwf = 0,7 20 1,0 = 14 /2;
βz∙ Rwz∙ γwz = 1,0∙ 0,45∙ 38∙ 0,85 = 14,54 /2.
.
4. :
An ≥ Af; Af = 30 ∙ 2 = 60 2; bn∙ tn = 260 ∙ 24 ; An = 62,4 2 > Af.
5. , , kf = kmin = 8 :
lw ≥ N / (βf κf Rwf γwf γc) = 1246 / (0,7 ∙ 0,8 ∙ 20 ∙ 1,0 ∙ 1,0) = 111,25 .
, kf = 20 .
lw ≥ 1246 / (0,7 ∙ 2 ∙ 20 ∙ 1,0 ∙ 1,0) = 44,6 .
, l = lw / 2 + 1 c = 44,6 / 2 + 1 = 23,3 c.
l = 24 , Δ = 20 ;
ln = 2∙ (24 +2) + 50 = 102 .
6. . 24 .
( ) l + Δ =
= 24 + 2 = 26 c. 20 ; bf + 2 a = 30 + 2∙ 2 = 34 .
7. , , , .
, , RA ( Δ = 20 , = 140 ). RA , , , .
M = RA∙ e = 400 ∙ 14 = 5600 ∙ Q = RA = 400 .
kf = 16 . ) , M Q ( lw = l 1 ).
x 1 x 1:
ΣSx 1 = 2∙ 0,7∙ 1,6∙ 252 / 2 + 2∙ 0,7∙ 1,6∙ 33∙ (25 + 4 + 1) = 2917,6 3;
|
|
( );
ΣAw = 2∙ 0,7∙ 1,6∙ 25 + 2∙ 0,7∙ 1,6∙ 33 = 129,92 2;
yct = ΣSx 1 / ΣAw = 2917 / 129,92 ≈ 22,5 .
x x, :
Jx = 2 [0,7∙ 1,6∙ 252 / 12 + 0,7∙ 1,6∙ 25∙ (22,5 25 / 2)2] +
+ [33∙ (2∙ 0,7∙ 1,6)3 / 12 + 2∙ 0,7∙ 1,6∙ 33∙ (25 + 4 + 1 22,5)2] = 12705,5 4;
( );
Wx,min = 12705,5 / 22,5 = 564,7 3.
:
σw = M / Wx,min = 5600 / 564,7 = 9,92 /2;
τw = Q / Aw = 400 / 129,92 = 3,1 /2;
√σw 2 + τw 2 = √ 9,922 + 3,12 = 10,4 /2 < Rwf∙ γwf∙ γc = 18 /2.
.
-
:
Apl,req = N /(Rb,locγc),
N , ;
Rb,loc = αφRb ;
Rb ;
α = 1 25;
φ Apl, < A (A ), 1,21,5.
B, L , Apl,req ; , 2430, 8090 2040 .
. . . , , .
tpl,req = √ 6 Mmax / (Ry∙ γc),
Mmax σb, (, ).
, ; , .
, , . .
.
|
|
1.
: N = 3210; 235;
: h = 500 ; f = 500 ; tw = 8 ; tf = 16 .
1. 7.5 (Rb = 0,45 /2) :
Rb,loc = αφRb = 1∙ 1,2∙ 0,45 = 0,54 /2.
2. .
.
Apl,req = N / Rb,loc = 3210 / 0,54 = 5944 2.
ttr = 10 , = 80 .
B = bf + 2∙ (ttr + c) = 500 + 2∙ (10 + 80) = 680 .
Lreq = Apl,req / B = 5944 / 68 = 87,4 .
L x B = 880 x 680 .
3. .
σb = N / (L ∙B) = 3210 / (88 ∙ 68) = 0,536 /2 < 0,54 /2.
:
1 (, 4 ) b = 468 ; a = 250 ;
b/a = 468 / 250 = 1,872. . 6.8 [2], , α 1 = 0,09688.
M 1 = α 1 ∙ σb∙ a 2 = 0,09688 ∙ 0,536 ∙ 252 = 32,5 ∙ .
2 (, 3 ) b= 190 ; a = 500 ;
b / a = 190 / 500 = 0,38 < 0,5. β = 0,125:
M 2 = β∙ σb∙ a 2 = 0,125 ∙ 0,536 ∙ 502 = 167,5 ∙ .
1. 2. b / a = 190 / 250 = 0,76. , . 6.9 [2] β = 0,0934.
M 2 = 0,0934 ∙ 0,536 ∙ 2 52 = 31,3 ∙ .
3 ( ).
M 3 = σb∙ c 2 / 2 = 0,536 ∙ 82 / 2 = 17,15 ∙ .
1, . , :
tpl = √ 6 Mmax / (Ry∙ γc) = √ 6 ∙ 32,5 / (23 ∙ 1,0) = 2,91 .
tpl = 30 .
4. .
. . ( I1):
βf∙ Rwf∙∙ γwf = 0,7 ∙ 18 ∙ 0,85 = 10,71 /2;
βz∙ Rwz∙ γwz = 1,0 ∙ 0,45 ∙ 36∙ 0,85 = 13,77 /2.
.
4- kf = ttr = = 10 , ,
htr = N / [ 4 kf (βf∙ Rwf∙∙ γwf)∙γc] + 1 =
= 3210 / (4∙ 1,0∙ 0,7∙ 18∙ 0,85∙ 1,0) + 1 = 75 .
htr = 750 .
, N .
. . ; , .
qtr = σb∙ (bf / 2 + ttr + c) = 0,536 ∙ (50 / 2 + 1 + 8) = 18,2 /.
Mtr = qtr∙ ctr 2 / 2 = 18,2 ∙ 192 / 2 = 3285,1 ∙.
Qtr = qtr∙ ctr = 18,2 ∙ 19 = 345,8 .
Wtr = ttr∙ htr 2 / 6 = 1 ∙ 752 / 6 = 937,5 3.
Mtr / (Wtr∙ Ry∙ γc) = 3285,1 / (937,5 ∙ 23∙ 1,0) = 0,152 << 1.
|
|
Qtr / (htr∙ ttr∙ Rs∙ γc) = 345,8 / (75 ∙ 1,0 ∙ 0,58 ∙ 23 ∙ 1,0) = 0,35 < 1.
5. ( 2).
; . 2.
qr = σb∙ bf / 2 = 0,536 ∙ 50 / 2 = 13,4 /.
Mr = qr∙ br 2 / 2 = 13,4 ∙ 192 / 2 = 2418,7 ∙.
Qr = qr∙ br = 13,4 ∙ 19 = 254,6 .
,
hr = √ 6 Mr / (tr∙ Ry∙ γc) = √ 6 ∙ 2418,7 / (1 ∙ 23∙ 1,0) = 25,1 .
hr = 300 .
Qr / (hr∙ tr∙ Rs∙ γc) = 254,6 / (30 ∙ 1,0 ∙ 0,58 ∙ 23 ∙ 1,0) = 0,636 < 1.
, , . kf = ttr = 10 .
τw = √ { 6 Mr / [βf∙ kf ∙ 2 (hr 1 ) 2 ]} 2 + {Qr / [βf ∙kf∙∙ 2 (hr 1 )]) 2 =
= √ {6∙ 2418,7 / [0,7∙ 1,0∙ 2∙ (30 1)2]}2 + (254,6 / [0,7∙ 1,0∙ 2∙ (30 1)]}2 =
= 13,83 /2 < 18∙ 0,85 = 15,3 /2 .
:
τw = √ { 6 Mr / [βz∙ kf ∙ 2 (hr 1 ) 2 ]} 2 + {Qr / [βz ∙kf∙∙ 2 (hr 1 )]) 2 =
= √ {6∙ 2418,7 / [1,0∙ 1,0∙ 2∙ (30 1)2]}2 + (254,6 / [1,0∙ 1,0∙ 2∙ (30 1)]}2 =
= 9,68 /2 < 0,45∙ 36∙ 0,85 = 13,8 /2 .
6. , .
:
kf ≥ qtr∙ L / [βf∙∙(L + 2 c)∙ Rwf∙∙ γwf =
= 18,2∙ 88 / [0.7∙ (88 + 2∙ 190∙ 18∙ 0,85] = 1,187 .
kf = 12 .
:
kf ≥ Qr / (βf∙∙ 2 br∙ Rwf∙∙ γwf) =
= 254,6 / (0.7∙ 2∙ 19∙ 18∙ 0,85) = 0,63 .
kf = 10 ( ). .
. 20
2.
: 402; 235;
N = 3210 ; Rb,loc = 0,54 /2.
1. Apl,req = 5944 2, = 600 . Lreq = Apl,req / B = 5944 / 60 = 99,1 . L x B = 1000 x 600 .
2.
σb = N / (L ∙B) = 3210 / (100 ∙ 60) = 0,535 /2 < 0,54 /2.
3. .
:
1 (, 4 ) b = 400 - 2∙ 20 = 360 ;
a = 200 13 / 2 = 193,5 ;
b/a = 360 / 193,5 = 1,86. . 6.8 [2], , α 1 = 0,1313.
M 1 = α 1 ∙ σb∙ a 2 = 0,1313 ∙ 0,535 ∙ 19,352 = 26,3 ∙ .
2 (, 4 ) b= 400 ;
a = 1000 / 2 200 -10 90 = 200 ;
|
|
b / a = 400 / 200 = 2. α 2 = 0,132:
M 2 = α 2 ∙ σb∙ a 2 = 0,132 ∙ 0,535 ∙ 202 = 28,25 ∙ .
3 (, 3 ).
= 400 ; b = 90 ; b / a = 90 / 400 = 0,225 < 0,5.
:
M 3 = σb∙ b 2 / 2 = 0,535 ∙ 92 / 2 = 21,67 ∙ .
4.
:
tpl = √ 6 Mmax / (Ry∙ γc) = √ 6 ∙ 28,25 / (23 ∙ 1,0) = 2,72 .
tpl = 28 .
4. .
.
βf∙ Rwf∙∙ γwf = 0,8 ∙ 18 ∙ 0,85 = 12,24 /2;
βz∙ Rwz∙ γwz = 1,0 ∙ 0,45 ∙ 36∙ 0,85 = 13,77 /2.
.
4- kf = ttr = = 10 , ,
htr = N / [ 4 kf (βf∙ Rwf∙∙ γwf)∙γc] + 1 =
= 3210 / (4∙ 1,0∙ 0,8∙ 18∙ 0,85∙ 1,0) + 1 = 66,6 .
htr = 670 .
.
qtr = σb∙ (bf / 2 + ttr + c) = 0,535 ∙ (40 / 2 + 1 + 9) = 16,05 /.
,
Mtr = qtr∙ ctr 2 / 2 = 16,05 ∙ 302 / 2 = 7222,5 ∙.
Qtr = qtr∙ ctr = 16,05 ∙ 30 = 481,5 .
Wtr = ttr∙ htr 2 / 6 = 1 ∙ 672 / 6 = 748 3.
Mtr / (Wtr∙ Ry∙ γc) = 7222,5 / (748 ∙ 23∙ 1,0) = 0,42 < 1.
Qtr / (htr∙ ttr∙ Rs∙ γc) = 481,5 / (67 ∙ 1,0 ∙ 0,58 ∙ 23 ∙ 1,0) = 0,54 < 1.
5. .
, ( ).
, 3 Agr = (9 + 20 / 2)∙ 40 = 760 2.
qd = σb∙ Agr / ld = 0,535 ∙ 760 / 40 = 10,165 /.
Mr = qd∙ ld 2 / 8 = 10,165 ∙ 402 / 8 = 2033 ∙.
Qd = qd∙ ld / 2 = 10,165 ∙ 40 / 2 = 203,3 .
,
hd= √ 6 Md / (td∙ Ry∙ γc) = √ 6 ∙ 2033 / (1,0 ∙ 23∙ 1,0) = 7,28 .
,
hdQ = Qd / (td∙ Rs∙ γc) = 203,3 / (1,0∙ 0,58∙ 23∙ 1,0) = 15,2 .
hd = 160 .
, :
τw = Q / (n ∙kf ∙βf∙ lw) = 203,3 / [2∙ 1,0∙ 0,8∙ (16 1)] = 8,5 /2 <
< Rwf ∙ γwf∙ γc = 18∙ 0,85∙ 1,0 = 15,3 /2 .
6. , .
lw = 2 (L 2 ) + 4 [(L hk) 4 ] =
= 2∙ (100 2) + 4∙ [(100 40] 4) = 420 .
kf ≥ 2 qtr∙ L / (lw∙ βf ∙ γwf∙ γc) = 2∙ 16,05∙ 100 / (420∙ 0,8∙ 18∙ 0,85∙ 1,0) = 0,62 .
kf = 7 , . 38* [1].
. 21
3.
: . 1.
. 22
1 . , , .
, , , 13 1 .
4. .
, , 1, 2 3 (. .):
Agr, 1 = 1/2 (bv 1 + bn 1 )∙ h 1 = 1/2∙ (6,75 + 19)∙ 12,25 = 157,72 2.
bv 1 = 190 245 / 2 = 67,5 .
Agr, 2 = 1/2 (bv 2 + bn 2 )∙ h 2 = 1/2∙ (22,3 + 46,8)∙ 12,25 = 423,24 2.
bv 2 = 468 2∙ 122,5 = 223 .
|
|
Agr, 3 = c∙ L = 8∙ 88 = 704 2.
Agr = Σ Agr,I = 2 Agr, 1 + Agr, 2 + Agr, 3 = 2∙ 157,72 + 423,24 + 704 = 1442,7 2.
, ,
Ntr = σb∙ Agr = 0,536∙ 1442,7 = 773,3 .
, 1, .
:
lw = Ntr / [ 2 kf (βf∙ Rwf∙∙ γwf)∙γc] = 773,3 / (2∙ 1,0∙ 0,7∙ 18∙ 0,85∙ 1,0) = 36,1 .
htr = lw + 1 = 36,1 + 1 =37, 1 ≈ 380 .
.
:
qtr = Ntr / L = 773,3 / 88 = 8,8 /.
:
Mtr,op = qtr∙ ctr 2 / 2 = 8,8 ∙ 192 / 2 = 1588,4 ∙.
():
Qtr,lev = qtr∙ ctr = 8,8 ∙ 19 = 167,2 .
. 23
:
Mtr,pr = qtr∙ l 2 / 8 = 8,8 ∙ 502 / 8 = 1161,6 ∙c.
:
Qtr,pr = qtr∙ L / 2 - Qtr,lev = 8,8∙ 88 / 2 167,2 = 220 .
: Wtr = 1∙ 382 / 6 = 240,7 3;
σtr = Mtr,op / Wtr = 1588,4 / 240,7 = 6,6 /2 < Ry∙γc = 23 /2;
τtr = Qtr,pr / Atr = 220 / (1 ∙ 38) = 5,8 /2 < Rs∙γc = 13,34 /2;
σef = √σtr 2 + 3 τtr 2 = √ 6,62 + 3∙ 5,82 = 12 /2 < 1,15 Ry∙γc = 26,45 /2.
5. .
4:
Agr,r = 2 Agr, 4 = 2 Agr, 1 = 2∙ 157,72 = 315,44 2.
Nr = σb∙ Agr,r = 0,536 ∙ 315,44 = 169,1 .
qr = Nr / br = 169,1 / 19 = 8,9 /.
1.
Mr = 8,9∙ 192 / 2 = 1606,2 ∙;
Qr = 8,9∙ 19 = 169,1 ;
hr = √ 6∙ 1606,2 / (1,0∙ 23∙ 1,0) = 20,47 .
hr = 240 .
169,1 / (24 ∙ 1,0 ∙ 0,58 ∙ 23 ∙ 1,0) = 0,53 < 1.
:
τw = √ { 6 Mr / [βz∙ kf ∙ 2 (hr 1 ) 2 ]} 2 + {Qr / [βz ∙kf∙∙ 2 (hr 1 )]) 2 =
= √ {6∙ 1606,2 / [0,7∙ 1,0∙ 2∙ (24 1)2]}2 + (169,1 / [0,7∙ 1,0∙ 2∙ (24 1)]}2 =
= 14 /2 < 15,3 /2 .
4.
: N = 4500 ; 345; 12;
2- 401.
1. [1] :
Ry = 31,5 /c2; Run = 47 /c2; Rwf = 21,5 /c2;
Rwz = 0,45 Run = 0,45∙ 47 = 21,15 /c2; Rb = 0,75 /c2;
βf = 0,7; βz = 1,0; γwf = 1,0; γwz = 0,85.
2. .
Rb,loc = αφRb = 1∙ 1,2∙ 0,75 = 0,9 /2.
Apl,req = N / Rb,loc = 4500 / 0,9 = 5000 2.
B = hk + 2 c = 388 +2∙ 80 = 548 .
= 550 . L= Apl,req / B = 90,9 . L= 910 .
ttr = 12 . (. .)
c = B / 2 - hk / 2 ttr = 550 / 2 388 / 2 12 = 69 ;
b = 400 9,5 = 390,5 ; = 388 ; 1 = 388 ; b 1 = 255 .
3. .
σb = N / (L ∙ B) = 4500 / (91 ∙ 55) = 0,899 /c2 < Rb,loc = 0,9 /c2.
1. b / a = 390,5 / 388 ≈ 1,0 α 1 = 0,048;
M 1 = α 1 ∙ σb∙ a 2 = 0,048 ∙ 0,899 ∙ 38,82 = 64,96 ∙ .
2. b 1 / a 1 = 255 / 388 = 0,6572 β = 0,082;
M 2 = β∙ σb∙ a 12 = 0,082 ∙ 0,899 ∙ 38,82 = 111,0 ∙ .
3.
M 3 = σb∙ c 2 / 2 = 0,899 ∙ 6,92 / 2 = 21,4 ∙ .
, .
, , 1 3 .
c = √ 6 M 1 / σb = √ 6 ∙ 54,96 / 0,899 = 12,02 . = 120 .
= 388 + 2∙ 120 = 628 . = 630 .
L = 5000 / 63 = 79,4 .
L = 800 . = 315 194 12 =
= 109 .
σb = 4500 / (80 ∙ 63) = 0,893 /c2
3.
M 3 = σb∙ c 2 / 2 = 0,893 ∙ 10,92 / 2 = 53 ∙ .
1.
M 1 = α 1 ∙ σb∙ a 2 = 0,048 ∙ 0,896 ∙ 38,82 = 64,5 ∙ .
.
2 : b 1 / a 1 = 205 / 388 = 0,5155 β = 0,0622;
M 2 = β∙ σb∙ a 12 = 0,0622 ∙ 0,896 ∙ 38,82 = 83,86 ∙ .
2.
tpl = √ 6 Mmax / (Ry∙ γc) = √ 6 ∙ 83,86 / (31,5 ∙ 1,0) = 3,99 .
.
2 , (. .). 2* :
b 1 = 200 ; a 1 = 388 / 2 = 194 ;
b 1 / a 1 = 200 / 194 = 1,031 ≈ 1,03 β = 0,1132;
M 2* = β∙ σb∙ a 12 = 0,1132 ∙ 0,896 ∙ 19,42 = 38,2 ∙ .
1, .
tpl = √ 6 Mmax / (Ry∙ γc) = √ 6 ∙ 64,5 / (31,5 ∙ 1,0) = 3,5 .
tpl = 36 .
4. .
, :
βf∙ Rwf γwf = 0,7 21,5 1,0 = 15,05 /2;
βz∙ Rwz∙ γwz = 1,0∙ 21,15∙ 0,85 = 17,98 /2.
.
kf = 14 , , tf = 14 .
htr = N / [ 4 kf (βf∙ Rwf∙∙ γwf)∙γc] + 1 =
= 3210 / (4∙ 1,4∙ 0,7∙ 21,5∙ 1,0∙ 1,0) + 1 = 54,4 .
htr = 550 .
5. , ( ):
Σlw = 2 L = 2 ∙ 81 = 162 ;
kf ≥ N / (Σlw∙ βf∙∙ Rwf ∙ γwf∙ γc) = 4500 / (162∙ 0,7∙ 21,5∙ 1,0∙ 1,0) = 1,85 .
kf = 20 .
6. .
.
1
qtr = σb∙ (a 1 / 2 + ttr + c) = 0,896 ∙ (38,8 / 2 + 1,2 + 10,9) = 28,22 /.
Mtr ≈ qtr∙ ltr 2 / 8 = 28,22 ∙ 812 / 8 = 23144 ∙.
Wtr = ttr∙ htr 2 / 6 = 1,2 ∙ 552 / 6 = 605 3.
Mtr / (Wtr∙ Ry∙ γc) = 23144 / (605 ∙ 31,5∙ 1,0) = 1,21 > 1.
.
tf = 16 . Wtr = 1,6 ∙ 552 / 6 = 807 3.
Mtr / (Wtr∙ Ry∙ γc) = 23144 / (807 ∙ 31,5∙ 1,0) = 0,91 < 1.
.
7. .
qr = σb∙ a 1* = 0,896 ∙ 19,42 = 17,38 /.
Mr = qr∙ b 12 / 2 = 17,38 ∙ 202 / 2 = 3476 ∙.
Qr = qr∙ b 1 = 17,38 ∙ 20 = 347,6 .
,
hr = √ 6 Mr / (tr∙ Ry∙ γc) = √ 6 ∙ 3476 / (1,6 ∙ 31,5∙ 1,0) = 20,3 .
hr = 220 .
Qr / (hr∙ tr∙ Rs∙ γc) = 347,6 / (22 ∙ 1,6 ∙ 0,58 ∙ 31,5 ∙ 1,0) = 0,54 < 1.
8. , .
. kf = 1,2 tr = 1,2∙ 16 ≈20 .
τw = √ {6∙ 3476 / [0,7∙ 2,0∙ 2∙ (22 1)2]}2 + (347,6 / [0,7∙ 2,0∙ 2∙ (22 1)]}2 =
= 18 /2 < 21,5 /2 .
. 24
5.
: N = 1580 ; 12 (= 0,75 /2;
27; 245.
1. = 300 .
2. :
Apl,req = N / (Rb,loc∙γc) = 1580 / (0,9 ∙ 1,0) = 1756 2,
Rb,loc = αφRb = 1∙ 1,2∙ 0,75 = 0,9 /2.
L B = 420 420 ; Apl = 42∙ 42 = 1764 2.
(. . 25).
. 25
3. .
σb = 1580 / 1764 = 0,896 /c2.
1. b / a = 300 / 270 = 1,11 α 1 = 0,055;
M 1 = α 1 ∙ σb∙ a 2 = 0,055 ∙ 0,896 ∙ 272 = 35,9 ∙ .
2. b 1 / a 1 = 60 / 270 = 0,22 < 0,5; b
M 2 = σb∙ b 2/ 2 =0,896 ∙ 62 = 16,13 ∙ .
3. b / a = 65 / 220 = 0,295 < 0,5
M 3 = 0,896 ∙ 6,52 / 2 = 18,93 ∙ .
1 , , (. .).
1* (): b / a = 300 / 135 = 2,22 > 2.
- α 1 = 0,125;
M 1 = α 1 ∙ σb∙ a 2 = 0,125 ∙ 0,896 ∙ 13,52 = 20,41 ∙ .
tpl = √ 6 Mmax / (Ry∙γc) = √ 620,41 / (24 ∙ 1,0) = 2,26 .
tpl = 24 .
4. .
.
:
βf∙ Rwf∙∙ γwf = 0,7 ∙ 18 ∙ 0,85 = 10,71 /2;
βz∙ Rwz∙ γwz = 1,0 ∙ 0,45 ∙ 37∙ 0,85 = 14,15 /2.
.
kf = tr = 10 ,
htr,req = Ntr / [ 8 kf (βf∙ Rwf∙∙ γwf)∙γc] = 1580 / (8∙ 1,0∙ 0,7∙ 18∙ 0,85∙ 1,0) = 18,44
htr = 200 .
. , .
( )
qtr = σb∙ (a / 2 + ttr + c) = 0,896 ∙ (27 / 2 + 1 + 6,5) = 18,8 /.
Mtr = qtr∙ b 2 / 2 = 18,8 ∙ 62 / 2 = 338,4 ∙.
Qtr = qtr∙ b = 18,8 ∙ 6 = 112,8 .
Wtr = ttr∙ htr 2 / 6 = 1 ∙ 202 / 6 = 66,7 3.
Mtr / (Wtr∙ Ry∙ γc) = 338,4 / (66,7 ∙ 24∙ 1,0) = 0,21 << 1.
Qtr / (htr∙ ttr∙ Rs∙ γc) = 112,8 / (20 ∙ 1,0 ∙ 0,58 ∙ 24 ∙ 1,0) = 0,405 < 1.
. , , , .
5. .
, 1, () . .
, , . ( ) :
Agr,d = a / 2∙ b = 27 / 2∙ 30 = 405 2.
qd = σb∙ Agr,d / ld = 0,896∙ 405 / 30 = 12,1 /.
Md = 12,1∙ 302 / 8 = 1361 ∙;
Qd = 12,1∙ 30 = 181,5 .
Wd,req = Md / (Ry∙ γc) = 1361 / (24∙ 1,0) = 56,7 3.
hd,req = √ 6 Wd,req / td = √ 6∙ 1361 / 1,0 = 18,44 .
hd = 190 .
Qtr / (hd∙ td∙ Rs∙ γc) = 181,5 / (19 ∙ 1,0 ∙ 0,58 ∙ 24 ∙ 1,0) = 0,686 < 1.
5. .
(. .):
Agr,d = 1/2∙ (bn + bv) ∙ 2 h = 1/2∙ (30 + 16,5)∙ 2∙ 6,75 = 313,86 2.
. 26
qd = σb∙ Agr,d / ld = 0,896∙ 313,86 / 30 = 9,4 /.
, , ,
Md = 9,4∙ 302 / 12 = 705 ∙;
Qd = 9,4∙ 30 = 141 .
Wd,req = Md / (Ry∙ γc) = 705 / (24∙ 1,0) = 29,4 3.
hd,req = √ 6 Wd,req / td = √ 6∙ 29,4 / 1,0 = 13,3 .
hd = 140 .
Qtr / (hd∙ td∙ Rs∙ γc) = 141 / (14 ∙ 1,0 ∙ 0,58 ∙ 24 ∙ 1,0) = 0,724 < 1.
. 27
6. , , .
τw = √ { 6 Mr / [βf∙ kf ∙ 2 (hd 1 ) 2 ]} 2 + {Qr / [βf ∙kf∙∙ 2 (hd 1 )]) 2 =
= √ {6∙ 705 / [0,7∙ 1,0∙ 2∙ (14 1)2]}2 + (254,6 / [0,7∙ 1,0∙ 2∙ (14 1)]}2 =
= 19,5 /2 > 15,3 /2.
. hd = 160 .
τw = √ {6∙ 2418,7 / [0,7∙ 1,0∙ 2∙ (16 1)2]}2 + (254,6 / [0,7∙ 1,0∙ 2∙ (16 1)]}2 =
= 15,02 /2 < 18∙ 0,85 = 15,3 /2 .
:
τw = √ { 6 Mr / [βz∙ kf ∙ 2 (hr 1 ) 2 ]} 2 + {Qr / [βz ∙kf∙∙ 2 (hr 1 )]) 2 =
= √ {6∙ 2418,7 / [1,0∙ 1,0∙ 2∙ (16 1)2]}2 + (254,6 / [1,0∙ 1,0∙ 2∙ (16 1)]}2 =
= 10,51 /2 < 0,45∙ 37∙ 0,85 = 14,15 /2 .
7. , .
:
kf ≥ qtr∙ Ltr / [βf∙∙(Ltr + b)∙ Rwf∙∙ γwf =
= 18,8∙ (2∙ 2 + 2∙ 1 + 6) / [0.7∙ (2∙ 2 + 2∙ 1 + 6 + 6)∙ 18∙ 0,85] = 1,17 .
kf = 12 .
:
kf ≥ qd∙ Ld / (βf∙∙ 2 Ld∙ Rwf∙∙ γwf) =
= 9,4∙ 30 / (0.7∙ 2∙ 30∙ 18∙ 0,85) = 0,45 .
38* [1] tpl = 24 kf = 8 .
6. .
, 5, :
263 (h = 262 ; bf = 260 ).
1. . 5.
2. , , , . 28 .
, , b∙ tpl, b .
M = σb∙ A∙c,
, ;
.
A = 1/2 (bn + bv)∙ h = 1/2 (42 + 26,2)∙ (21 13) = 272,8 2.
c = ( 2 bn + bv) h / [ 3 ∙ (bn + bv)] = (2 ∙ 42 +26,2) ∙ 8 / [3∙ (42 + 26,2)] = 4,3 .
= 0,896∙ 272,8∙ 4,3 = 1053,2 ∙ .
tpl = √ 6 M / b∙ Ry = √ 6 ∙ 1053,2 / (26,2∙ 24) = 3,17 .
tpl = 32 .
, , , , .
1. : Ak = h∙ bf = 26,2∙ 26 = 681,2 2.
2. : Ak* = π∙ d 2 / 4;
dk = √ 4 Ak / π = √ 4 ∙ 681,2 / 3,14 = 29,5 .
3. Apl = 42 x 42 = 1764 2;
dpl = √ 4 ∙ 1764 / 3,14 = 47,4 .
4.
β = dk / dpl = 0,62 ≈ 0,6.
, kr = 0,02 kτ = 0,0377 ( . 6.10 [2]);
5. Mr Mτ 1 :
Mr = kr∙ N = 0,02 ∙ 1580 = 31,6 ∙ ;
Mτ = kτ∙ N = 0,0377 ∙ 1580 = 59,6 ∙ ;
6. , tpl = 36 (, ):
σr = 6 Mr / tpl 2 = 6∙ 31,6 / 3,62 = 14,63 /2;
στ = 6 Mτ / tpl 2 = 6∙ 59,6 / 3,62 = 27,59 /2;
τ = N / ( 2 π∙ b∙ tpl) = 1580 / (2 ∙ 3,14 ∙ 26,2 ∙ 3,6) = 2,67 /2.
7.
σf = √ σr 2 + στ 2 σr∙ στ + 3 τ 2 =
√ 14,632 + 27,592 14,63∙ 27,59 + 3∙ 2,672 = 24,35 /2 <
< 1,15 Ry ∙ γc = 1,15∙ 24∙ 1,0 = 27,6 /2.
.
7. : 261;
N = 1580 ; 12 (Rb = 0,75 /c2);
245 (Ry = 24 /2).
. 29
(. .).
: 1- , 2- .
. . 4.21, [2] = 131 < 400 = 210 , 2 ≥ . 2 = 2∙ 131 = 262 > 210 , .
1. .
1. b / a = 210 / 131 = 1,6 → β = 0,128;
M 1 = β∙ σb∙ a 2 = 0,128∙ 0,896∙ 13,12 = 19,68 ∙.
2. M 2 = σb∙ c 2 / 2 = 0,896 ∙ 7,92 / 2 = 27,96 ∙.
2 1.
, , .
440 400 . Apl = 44∙ 40 = 1760 2 σb* = = N / Apl = 1580 / 1760 = 0,898 /c2 < σb,loc = 0,9 /2.
1*. b / a = 220 / 131 = 1,68 → β = 0,1288;
M 1 = β∙ σb∙ a 2 = 0,1288∙ 0,898∙ 13,12 = 19,85 ∙.
2*. M 2 = σb∙ c 2 / 2 = 0,898 ∙ 6,92 / 2 = 21,38 ∙.
tpl = √ 6 Mmax / (Ry∙ γc) = √ 6 ∙ 21,38 / (24 ∙ 1,0) = 2,31 .
tpl = 24 .
2. , .
) , .
qr, 1 = σb∙ a = 0,898 ∙ 13,1 = 11,76 /.
:
Mr, 1 = qr, 1∙ b 2 / 2 = 11,76∙ 222 / 2 = 2845,92 ∙;
Qr, 1 = qr, 1∙ b = 11,76∙ 22 = 258,72 .
, tr = 10 :
Wr 1, req = Mr, 1 / (Ry∙ γc) = 2845,92 / (24∙ 1,0) = 118,58 3;
hr 1, req = √ 6 ∙ Wr 1, req / tr = √ 6 ∙ 118,58 / 1,0 = 26,67 .
, , hr 1 = 310 .
, kf = 10 :
-
τw = √ { 6 Mr, 1 / [βf∙ κf∙ 2 ∙(hr 1 1 ) 2 } 2 +
+ { Qr, 1 / [ βf∙∙κf∙ 2 ∙∙(hr 1 1 )} 2 =
= √ {6∙ 2845,92 / [0,7∙ 1,0∙ 2∙ (31 1)2}2 + {258,72 / [0,7∙ 1,0∙ (31 - 1)}2 =
= 14,88 /c2 < Rwf∙ γwf∙ γc = 18 ∙ 0,85 ∙ 1,0 = 15,3 /c2;
-
τw = √ { 6 Mr, 1 / [β∙ κf∙ 2 ∙(hr 1 1 ) 2 } 2 +
+ { Qr, 1 / [ β∙∙κf∙ 2