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Jumlah tulangan dalam 1 m =
04 ,
113 364
= 3,22 ≈ 4 tulangan
Jarak tulangan 1 m =
4 1000
= 250 mm
Dipakai tulangan 4 ∅ 12 mm – 200 mm
As yang timbul = 4 . ¼ x
π x d
2
= 452,16 mm
2
As 364 ........aman
4.5. Perencanaan Balok Bordes
20 qu balok 260
20
3 m
150
Data perencanaan: h = 300 mm
b = 150 mm d`= 40 mm
d = h – d` = 300 – 40 = 260 mm
4.5.1. Pembebanan Balok Bordes ¾ Beban mati q
D
Berat sendiri = 0,15 x 0,30 x 2400
= 108 kgm Berat dinding
= 0,15 x 2 x 1700 = 510 kgm
Berat plat bordes = 0,15 x 2400
= 360 kgm q
D
= 978 kgm
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¾ Akibat beban hidup q
L
q
L
= 300 kgm ¾ Beban ultimate q
U
q
U
= 1,2 . q
D
+ 1,6. q
L
= 1,2 . 978 + 1,6.300 = 1653,6 kgm
¾ Beban reaksi bordes ¾ q
u
= bordes
lebar bordes
aksi Re
= 2
6 ,
1653 .
2 1
= 413,4 Kgm 4.5.2.
Perhitungan tulangan lentur Tulangan tumpuan
M
u
= 1860,3 kgm = 1,8603.10
7
Nmm Mn
= φ Mu
= =
8 ,
10 .
8603 ,
1
7
2,32 . 10
7
Nmm m
= 29
, 11
25 .
85 ,
240 .
85 ,
= =
fc fy
ρb = ⎟⎟
⎠ ⎞
⎜⎜ ⎝
⎛ +
β fy
600 600
. .
fy fc
. 85
,
= ⎟
⎠ ⎞
⎜ ⎝
⎛ + 240
600 600
. 85
, .
240 25
. 85
, =
0,053 ρ
max
= 0,75 . ρb
= 0,75 x 0.053 = 0,04 ρ
min
= 0058
, 240
4 ,
1 4
, 1
= =
fy Rn =
=
2
.d b
Mn =
2 7
260 .
150 10
. 32
, 2
2,3 Nmm
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ρ
ada
= ⎟⎟
⎠ ⎞
⎜⎜ ⎝
⎛ −
− fy
2.m.Rn 1
1 m
1
= .
29 ,
11 1
⎟⎟ ⎠
⎞ ⎜⎜
⎝ ⎛
− −
240 3
, 2
. 29
, 11
. 2
1 1
= 0,01
ρ
ada
ρ
max
ρ
ada
ρ
min
di pakai ρ
ada
= 0,01 As =
ρ ada . b . d = 0,01 x 150 x 260
= 390 mm
2
Dipakai tulangan ∅ 12 mm
= ¼ . π x 12
2
= 113,04 mm
2
Jumlah tulangan =
04 ,
113 390
= 3,45 ≈ 4 buah
As yang timbul = 4. ¼ .
π. d
2
= 452,16 mm
2
As 390 ....... Aman
Dipakai tulangan 4 ∅ 12 mm
4.5.3. Perhitungan Tulangan Geser Balok Bordes
Vu = 2480,4 kg = 24804 N Vc =
. c
f b.d.
. 6
1 = 16 . 150 . 260. 25 .
= 32500 N ∅ Vc
= 0,75 . Vc = 24375 N
3 ∅ Vc
= 73125 N Vu
∅ Vc Jadi di perlukan tulangan geser
Ø Vs = Vu - Ø Vc
= 24804 – 24375 = 429 N Vs perlu =
75 ,
Vs φ
= 75
, 429
= 572 N
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Pu Mu
1.25 0.75
0.25
Av = 2 . ¼
π 8
2
= 2 . ¼ . 3,14 . 64 = 100,48 mm
2
s = 14615
429 260
240 48
, 100
perlu Vs
d .
fy .
Av =
× ×
= mm
S max = d2 = 2
260 = 130 mm
Jadi dipakai sengkang dengan tulangan D 8 – 100 mm
4.6. Perhitungan Pondasi Tangga
Gambar 4.3 Pondasi Tangga
Direncanakan pondasi telapak dengan kedalaman 1,25 m dan panjang 1,40m - Tebal
= 250 mm - Ukuran alas
= 1400 x 1250 mm -
γ tanah = 1,7 tm
3
= 1700 kgm
3
- σ tanah
= 3 kgcm
2
= 30000 kgm
2
- Pu =
10704.30 kg
- h = 250 mm
- d = h - p - 12 Ø
t
- Ø
s
= 250 – 40 – ½ .12 – 8 = 196 mm
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4.7. Perencanaan kapasitas dukung pondasi
