4.5.3. Perhitungan Pintu Gerbang Kembar Baja Saluran C
m g t g t
L t g t g m
L tot W
+ 31,00 + 26,75
+ 33,00 + 36,00
+ 37,00
Gambar 4.32
Pintu Gerbang Saluran C
1. Perhitungan Dimensi balok Horisontal a. Perhitungan Pembebanan
q =
γ
w
.½.h
1
+h
2
.b q
1
= 1 x ½ 8,856 + 9,25.0,394 = 3,565 tm
q
2
= 1 x ½ 8,444 + 8,856.0,412 = 3,565 tm
q
3
= 1 x ½ 8,011 + 8,444.0,433 = 3,565 tm
q
4
= 1 x ½ 7,553 + 8,011.0,458 = 3,565 tm
q
5
= 1 x ½ 7,065 + 7,553.0,488 = 3,565 tm
q
6
= 1 x ½ 6,541 + 7,065.0,524 = 3,565 tm
q
7
= 1 x ½ 5,971 + 6,541.0,57 = 3,565 tm
q
8
= 1 x ½ 5,341 + 5,971.0,63 = 3,565 tm
q
9
= 1 x ½ 4,625 + 5,341.0,716 = 3,565 tm
q
10
= 1 x ½ 3,776 + 4,625.0,849 = 3,565 tm
q
11
= 1 x ½ 2,67 + 3,776.1,106 = 3,565 tm
q
12
= 1 x ½2,67.2,67 = 3,565 tm
Diambil beban maksimum: q
h
= 3,565 tm b. Perhitungan Lebar Gerbang secara praktis
L =
2 2
12W 16W
=
2 2
7,9 x
12 7,9
x 16
= 4,16367 m = 416,367 cm c. Momen Yang Terjadi :
1. Momen Pada Balok Horisontal : q
h
= 3,565 tm = 35,65 kgcm M = 18.q
h
.L
2
= 18 x 35,65 x 416,367
2
= 772642,145 kg cm
2. Momen pada balok vertikal M = 18.q
v
.b
2
Dimana : b = sisi panjang jarak antar balok horisontal
q
v
= beban masing-masing segmen b
1
= 40,295 cm b
2
= 42,27 cm b
3
= 44,57 cm b
4
= 47,295 cm b
5
= 50,595 cm b
6
= 54,7 cm b
7
= 60,015 cm b
8
= 67,295 cm b
9
= 78,215 cm b
10
= 97,74 cm b
11
= 144,307 cm b
12
= 178,013 cm
m
1
= 18 x 35,65 x 40,295
2
= 7236,508 kg cm
m
2
= 18 x 35,65 x 42,27
2
= 7963,266 kg cm
m
3
= 18 x 35,65 x 44,57
2
= 8853,439 kg cm
m
4
= 18 x 35,65 x 47,295
2
= 9969,128 kg cm
m
5
= 18 x 35,65 x 50,595
2
= 11408,851 kg cm
m
6
= 18 x 35,65 x 54,7
2
= 13335,256 kg cm
m
7
= 18 x 35,65 x 60,015
2
= 16052,635 kg cm
m
8
= 18 x 35,65 x 67,295
2
= 20183,306 kg cm
m
9
= 18 x 35,65 x 78,215
2
= 27265,082 kg cm
m
10
= 18 x 35,65 x 97,74
2
= 42576,64 kg cm
m
11
= 18 x 35,65 x 144,307
2
= 92811,011 kg cm
m
12
= 18 x 35,65 x 178,013
2
= 141231,567 kg cm
d. Penentuan Profil σ
ijin
=
nt
W M
dengan M = 772642,145 kg cm W
nt
= 0,8.W
br
W
br
=
1,25.M
=
1400 772642,145
x 1,25
= 689,859 cm
3
1. Dicoba profil IWF 350 x 175 x 7 x 11 h
= 35 cm W
x
= 775 cm
3
b = 35 cm
I
x
= 13600 cm
4
d = 0,7 cm
t = 1,1 cm
a. Cek terhadap Kekuatan Bahan Terhadap lentur :
σ =
x
W M
=
3330 772642,145
= 996,958 kgcm
2
σ σ
ijin
= 1400 kgcm
2
Aman Terhadap Geser :
D = ½.q.L = ½ x 35,65 x 416,367 = 7422,711 kg S
x
= d.½.h.¼.h + b - d.t.½.h - t = 0,7.½.35.¼.35 + 35 - 0,7.1,1.½.35 - 1,1 = 420,424 cm
3
τ =
x x
d.I D.S
= 1360
x 3
, 1
420,424 x
7422,711 = 20,86 kgcm
2
τ τ
ijin
= 0,58. σ
ijin
= 812 kgcm
2
Aman Terhadap lendutan :
ƒ =
x 2
48.E.I .M
5.L =
13600 x
10 x
2,1 x
48 772642,145
x 416,367
x 5
6 2
= 0,513 cm ƒ ƒ
ijin
= 1500.L = 1500 x 416,367 = 0,833 cm Aman
2. Profil C 350 x 100 x 14 x 16 h
= 35 cm W
x
= 734 cm
3
b = 10 cm
I
x
= 12840 cm
4
d = 1,4 cm
t = 1,6 cm
h d
t b
d t
b h
a. Cek terhadap kekuatan bahan Terhadap lentur
σ =
x
W M
=
754 772642,145
= 1052,646 kgcm
2
σ σ
ijin
= 1400 kgcm
2
Aman Terhadap Geser :
D = ½.q.L = ½ x 35,65 x 416,367 = 7422,711 kg S
x
= d.½.h.¼.h + b - d.t.½.h - t = 1,4.½.35.¼.35 + 10 - 1,4.1,6.½.35 - 1,6 = 444,167 cm
3
τ =
x x
d.I D.S
= 1284
x 4
, 1
444,167 x
7422,711 = 160,481 kgcm
2
τ τ
ijin
= 0,58. σ
ijin
= 812 kgcm
2
Aman Terhadap lendutan :
ƒ =
x 2
48.E.I .M
5.L =
12840 x
10 x
2,1 x
48 772642,145
x 416,367
x 5
6 2
= 0,543 cm ƒ ƒ
ijin
= 1500.L = 1500 x 416,367 = 0,833 cm Aman
2. Perhitungan Tebal Pelat Penutup a = jarak antar balok vertikal = 17 L = 17 x 416,367 = 59,481 cm
b = jarak antar balok horisontal Perhitungan:
σ
ijin
= 1400 kgcm
2
dan k = 0,8 P
= ½.γ
w
.h
1
+ h
2
σ
ijin
=
2 2
2 2
2
t b
a .b
12.k.P.a
Tabel 4.6
Tebal Pelat Penutup Pintu Gerbang C Segmen
b cm h
1
cm h
2
cm P kgcm
2
t cm 1
19,69 9,25
9,053 9,152
0,302 2
40,295 9,053
8,65 8,852
0,531 3
42,27 8,65
8,227 8,439
0,535 4
44,57 8,227
7,782 8,005
0,539 5
47,295 7,782
7,309 7,545
0.544 6
50,595 7,309
6,803 7,056
0.547 7
54,7 6,803
6,256 6,529
0,55 8
60,015 6,256
5,656 5,956
0,551 9
67,295 5,656
4,983 5,319
0,549 10
78,215 4,983
4,201 4,592
0,542 11
97,74 4,201
3,223 3,712
0,523 12
144,307 3,223
1,78 2,502
0,465 13
178,013 1,78
0,89 0,284
Tebal penutup maksimum pada segmen dengan t = 0,551 cm. Tebal penutup pintu gerbang diambil 6 mm.
3. Perhitungan Tebal Penutup Pintu Gerbang a. Tebal Pintu Gerbang
tp = h + 2t = 35 + 2 x 0,6 = 36,2 cm
Dimana : h = tinggi balok cm
t = tebal pelat penutup pintu cm
b. Perhitungan Lebar Pintu Gerbang tp = 36,2 cm
j = 15.tp = 7,24 cm
n = 25 cm
m = 3 cm p
= 15 cm z
= 12 cm α = 15
o
L =
o
Cos tp2
m z
w2
+ tp2 + j.tg
α
=
o
15 Cos
36,22 3
12 7902
+ 36,22 + 7,24 tan 15
o
= 463,242 cm, diambil lebar pintu gerbang 470 cm
39,38 41,21
71,55 84,88
110,60 267,02
63,04 56,99
52,41 48,78
45,81 43,33
100,00 178,01
144,31 97,74
78,22 67,30
60,02 54,70
50,60 47,30
44,57 42,27
40,30 19,69
67 67
67 67
67 67,5
69,6
470 1025
925
Gambar 4.33
Pembebanan dan Penempatan Profil Pintu Gerbang Saluran C
4. Perhitungan Engsel Pintu Gerbang Dimensi engsel akan dihitung berdasarkan spesifikasi dan beban yang
bekerja pada masing-masing gerbang.
a G
Pintu Gerbang
Ambang Kg1
Kg2 P
Ambang Fb
Kw1
Kw2 Fb
H h
0,5 m H
1 3
H
2 3
H H
Gambar 4.34
Pembebanan pada Engsel Pintu Gerbang C
a. Dimensi Engsel Atas 1. Spesifikasi Pintu Gerbang
Lebar gerbang = 4,7 m Tinggi gerbang = H + Fb = 9,25 + 1 = 10,25 m
Profil horizontal : IWF 350 x 175 x 7 x 11 dengan berat 49,6 kgm Profil vertikal : IWF 350 x 175 x 7 x 11 dengan berat 49,6 kgm
Tebal pelat penutup : 0,006 m dengan γ
besi
= 7850 kgm
3
Profil C 35 x 100 x 14 x 16: 60,6 kgm
2. Berat Pintu Gerbang Balok vertikal : C 35 = 2 x 10,25 x 60,6
= 1242,3 kg
IWF 350 x 175 x 7 x 11 = 6 x 10,25 x 49,6 =
3050,4 kg Balok horizontal : C 35 = 2 x 4,7 x 60,6
= 569,64 kg
IWF 350 x 175 x 7 x 11 = 13 x 4,7 x 49,6 =
3030,56 kg Pelat = 2 x 10,25 x 3,95 x 0,006 x 7850
= 3813,923 kg +
Q = 11706,823 kg
Safety Factor = 15 x Q = 0,15 x 11706,823 = 1756,023 kg
Berat pintu G = 11706,823 + 1756,023 = 13462,846 kg 3. Keseimbangan Akibat Berat Pintu
a = 0,5 x 4,7 = 2,35 m G = 13462,846 kg
Kg =
h a
G x
=
10,25 2,35
x 13462,846
= 3086,604 kg Kg
1
= Kg = 3086,604 kg
←
Kg
2
= Kg = 3086,604 kg
→
4. Keseimbangan Akibat Tekanan Hidrostatis Fb = tinggi jagaan freeboard = 1 m, L = lebar pintu = 4,7 m
Tinggi ambang = 1 m, H = 9,25 m H’ = H - tinggi ambang = 9,25 - 1 = 8,25 m
P = ½. γ
w
H’
2
.L = ½ x 1 x 8,25
2
x 4,7 = 159,947 t = 159946,875 kg Kw
1
=
h H
P
3 1
=
10,25 8,25
x 159946,875
3 1
= 42912,576 kg
→
Kw
2
=
h H
PFb
3 2
=
10,25 8,25
x 1
159946,875
3 2
= 101429,726 kg
←
5. Perhitungan Diameter Pen Engsel K’ =
2 1
2 1
Kw Kg
=
2 2
42912,576 3086,604
= 43023,439 kg y
= 10 cm M = y.K
1
= 10 x 43023,439 = 430234,39 kg cm W =
32 D
.
3
dan W =
ijin
M
→ σ
ijin
= 1400 kgcm
2
32 D
. 14
, 3
3
=
1400 430234,39
→ D = 14,631 cm
Diambil diameter pen engsel = 15 cm Check terhadap geser :
τ =
2
R .
. 3
K .
4
=
2
7,5 x
3,14 x
3 430234,39
x 4
= 324,782 kgcm
2
τ τ
ijin
= 812 kgcm
2
Aman 6. Perhitungan Diameter Stang Angker
K” = ½.K’.cos½. α = ½ x 43023,439 x cos ½ x 45° = 19874,032 kg
F =
K
→ σ
ijin
= 1400 kgcm
2
¼. π.D
2
=
1400 19874,032
→ D = 4,252 cm Diambil diameter stang angker = 5 cm = 50 mm
7. Perhitungan Diameter Pelat Angker a. Perhitungan berdasarkan tegangan geser beton.
b. Pelat angker dipasang sedalam 20 cm di dalam dinding beton. σ
bs
= 0,56
bk
= 0,56 225 = 8,4 kgcm
2
F =
bs
K
3 a x L =
4 ,
8 19874,032 → a = 39,433 cm
3 adalah banyaknya bidang geser, yaitu: kiri, kanan, bawah. Diambil ukuran pelat angker 40 x 40 cm
c. Tinjauan terhadap potongan I - I M = ½.
σ
bs
.a.½.a
2
= 18 σ
bs
.a
3
= 18 x 8,4 x 40
3
= 8400 kg cm W = 16.a.
δ
2
dan W =
ijin
M
→ σ
ijin
= 1400 kgcm
2
16 x 40 x δ
2
=
1400 8400
→ δ = 2,683 cm d. Tinjauan terhadap potongan II - II
P = ½.a
2
. σ
bs
= ½ x 40
2
x 8,4 = 6720 kg M = P.
⅓.½.a 2 = 6720 x ⅓ x ½ x 40 x 2 = 63356,768 kg cm 16 x 40 x
δ
2
=
1400 63356,768
→ δ = 2,605 cm Diambil tebal pelat angker = 2,7 cm
b. Dimensi Engsel Bawah 1. Perhitungan Diameter Pen Engsel
K
2
= Kw
2
= 101429,726 kg G = 13462,846 kg
F =
ijin
G
→ σ
ijin
= 1400 kgcm
2
¼. π.D
2
=
1400 13462,846
→ D = 3,5 cm Diambil diameter pen angker = 4 cm = 40 mm
Check terhadap geser : τ
ijin
=
2 2
R .
. 3
K .
4
σ
ijin
= 812 kgcm
2
814 =
2
R x
3,14 x
3 101429,726
x 4
→ R = 7,283 cm ≈ 8 cm Diambil diameter pen angker = 16 cm = 160 mm
2. Perhitungan Pelat Andas a. Perhitungan plat I
σ’
bk
= 225 kgcm
2
F =
bk
G
a
2
=
225 13462,846
→ a = 7,735 cm, b. Perhitungan plat II
σ’
bk
= 225 kgcm
2
F =
bk 2
K
a
2
=
225 101429,726
→ a = 21,232 cm, diambil ukuran 25 x 25 cm c. Tinjauan potongan I - I
I
I a
a
M = ½. σ
bs
.a.½.a
2
=18. σ
bs
a
3
= 18 x 8,4 x 25
3
= 16406,25 kg cm W = 16.a.
δ
2
dan W =
ijin
M
→ σ
ijin
= 1400 kgcm
2
16 x 25 x δ
2
=
1400 16406,25
→ δ = 1,677 cm ; diambil tebal 1,7 cm
4.6. PERHITUNGAN DINDING GERBANG DAN KAMAR 4.6.1. Perhitungan Konstruksi Dinding Gerbang A
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