1
Primer 1.
Odrediti potrebnu površinu armature za stub poznatih
dimenzija, pravougaonog popre
č
nog preseka, optere
ć
en
momentima savijanja usled stalnog (M
g
) i povremenog
(M
w
) optere
ć
enja vetrom. Podaci za prora
č
un:
M
g
= 100 kNm
M
w
= ±200 kNm
b = 25 cm
d = 65 cm
MB 30
RA 400/500
b
=
25
d = 65
M
g
±M
w
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2
a. zategnuta spoljašnja ivica stuba
M
u
= 1.6×100 + 1.8×200 = 520 kNm
pretp. a
1
= 7 cm
h = 65 - 7 = 58 cm
MB 30
⇒
f
B
= 20.5 MPa
b
=
25
d = 65
M
g
=100
M
w
=200
821
.
1
05
.
2
25
10
520
58
k
2
=
×
×
=
%
281
.
37
‰
10
.
4
/
5
.
3
/
a
b
=
⇒
=
µ
ε
ε
2
a
cm
70
.
27
40
05
.
2
100
58
25
281
.
37
A
=
×
×
×
=
usvojeno:
6R
Ø
25
(29.45 cm
2
)
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4
2
2
.5
28
4
.5
4
.5
4.5
25
65
2x8
4.5
5
.5
3R
Ø
25
3R
Ø
25
2R
Ø
12
U
Ø
8/20
3R
Ø
25
SPOLJA
UNUTRA
a
I
= 2.5 + 0.8 + 2.5/2 = 4.55 cm
usv. a
I
= 4.5 cm
a
II
= 4.5 + 3.0 + 2.5 = 10 cm
a
1
= (4.5 + 10)/2 = 7.25 cm
a
2
= 4.5 cm
h = 65 - 7.25 = 57.75 cm
h
≈
58 cm = h
ra
č
.
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5
Primer 2.
Odrediti potrebnu površinu armature za stub poznatih
dimenzija, pravougaonog popre
č
nog preseka, optere
ć
en
zadatim uticajima. Podaci za prora
č
un:
M
g
= 100 kNm
N
g
= 500 kN
M
w
= ±200 kNm
b = 25 cm
d = 65 cm
MB 30
RA 400/500
b
=
25
d = 65
M
g
±M
w
N
g
PDF created with pdfFactory trial version
www.pdffactory.com
