4.10.3. Momen tumpuan kanan frame 287 Mu = 355,90 kNm
Data Perencanaan Balok Induk 80
40 direncanakan :
Tulangan lentur : D22 mm ; fc’
= 30 Mpa Tulangan geser
: Φ12 mm ; fy
= 400 Mpa Tinggi balok h : 800 mm ;
β = 0,85
Lebar balok b : 400 mm
Selimut beton p : 40 mm Tinggi efektif d = h-p-Ø tul sengkang-
2 tullentur
= 800-40-12- 2
22 = 737 mm
fy x
fy xfc
x maks
600 600
85 .
75 .
1
400 600
600 400
30 85
. 85
. 75
.
x
x x
x maks
= 0.023
fy 4
. 1
min
400 4
. 1
min
= 0.0035
85 .
xfc fy
m
30 85
. 400
x m
= 15.68
91
2
xbxd Mu
Rn
2
737 400
8 .
90 ,
355 x
x Rn
= 2,05
fy
xmxRn x
m perlu
2 1
1 1
400
05 .
2 68
. 15
2 1
1 68
. 15
1 x
x x
perlu
= 0.0053
Syarat : ρmin ρperlu ρmax
0.0035 0.0053 0.023 maka dipakai
ρperlu = 0.0053 As perlu =
ρ x b x d = 0.0053x 400 x 737
= 1575,08 mm
2
dipakai 6D22 As ada = 2281 mm
2
As’ perlu = 50 As = 0,5 x 2281 mm
2
= 920,12 mm
2
dipakai 4D22 As ada = 1521 mm
2
Syarat : As min
1
= d
b fy
fc
4
= 737
400 400
4 30
x = 1009.18 mm
2
As min
2
= d
b fy
4 ,
1 =
737 400
400 4
, 1
x x
= 1031.8 mm
2
As min
1
≤ As ≥
As min
2
1009.18 mm
2
≤ 2281 mm
2
≥ 1031.8 mm
2
........... OK
92
Kontrol analisa penampang :
a = b
fc fy
As
85 ,
= 400
30 85
, 400
2281 x
x x
= 89.45
ØMn = ØAs.fy.d- 2
a
ØMn =
2 45
. 89
737 400
2281 8
, x
x x
x10
-6
= 505.31 kNm ØMn
≥ Mu 505.31 kNm
≥ 355,90 kNm ...............OK
Kontrol jarak tulangan = b–2xselimut beton–2xtul.Sengkang–
5xtul.lentur = 400 - 2x40 - 2x12 – 6x22
= 164
mm Syarat
:
1 6
164 = 32.8 22 .....................OK
6D22
400
4D22
3
12
800
Gambar 4.12. Penampang Balok Ukuran 4080 pada Tumpuan Bentang Kanan
93
4.10.4. Kontrol Torsi
1 0 2 0 3 0 0
8 0 0
Gambar 4.13. Penampang Balok Torsi
Tu = 0,23 kNm
Tn = Tu
=
0,23 0,75 =
0,31 kNm Acp =
400 x 800 = 320000 mm
2
Pcp = 2 400 + 800 = 2400 mm
Syarat : Tu =
Pcp Acp
fc
2
. 12
Tu = 0,23 kn m
= 2400
320000 .
12 30
7 ,
.10 5
2 -6
= 14,61 kn m
Tu = 0,23 kn m Maka pengaruh torsi diabaikan
Karena tinggi balok h = 800 mm maka dipasang tulangan praktis 2D22 As=760,3 mm
2
10 As tul tarik pokok = 10x2281mm
2
= 228,1 mm
2
. 94
4.10.5. Penulangan Geser Balok
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