Perhitungan Pembebanan pada Pondasi Jembatan A. Beban Voided Slab
I. Data Voided Slab
Panjang Jembatan (P) = 11.60 m Lebar Jembatan (L) = 15.00 m
Luas Jembatan = P x L
= 174.00 m2
Digunakan voided slab tipe PC VS-67/97 dengan data berikut:
B = 0.97 m
H = 0.67 m
L = 11.60 m
d = 0.30 m
Luas 1 modul voided slab = B x L
= 11.25 m2
Jumlah voided slab =
=
= 15.46 bh
= 16.00 bh
Volume void =
=
= 26.24 m3 Volume total voided slab =
=
= 94.38 m3 II. Data Material
Mutu beton = 400.00 kg/cm2
Fc' = 33.20 MPa
Ec (modulus elastisitas) = 27,081.14 MPa
Bj Beton = 2,400.00 kg/m3
Bj Aspal = 2,200.00 kg/m3
III. Beban-beban yang Bekerja pada Voided Slab a) Beban Mati QDL)
1) Berat sendiri voided slab
Volume voided slab = 94.38 m3
Berat sendiri voided slab = Vol. voided slab x Bj beton 1
4𝑥 𝜋 𝑥 𝑑 𝑥 𝐿 𝑥 𝑞𝑡𝑦 𝑣𝑜𝑖𝑑 𝑥 𝑞𝑡𝑦 𝑣𝑜𝑖𝑑𝑒𝑑 𝑠𝑙𝑎𝑏 1
4𝑥 𝜋 𝑥 0.30 𝑥 11.60 𝑥 2 𝑥 16 𝐿𝑢𝑎𝑠 𝑗𝑒𝑚𝑏𝑎𝑡𝑎𝑛
𝐿𝑢𝑎𝑠 1 𝑚𝑜𝑑𝑢𝑙 𝑣𝑜𝑖𝑑𝑒𝑑 𝑠𝑙𝑎𝑏 174.00
11.25
𝐵 𝑥 𝐻 𝑥 𝐿 𝑥 𝑞𝑡𝑦 𝑣𝑜𝑖𝑑𝑒𝑑 𝑠𝑙𝑎𝑏 − 𝑣𝑜𝑙𝑢𝑚𝑒 𝑣𝑜𝑖𝑑 0.97 𝑥 0.67 𝑥 11.6 𝑥 16 − 26.24
= 94.38 x 2,400.00
= 226,518.86 kg
= 226.52 ton
2) Berat concrete slab
Luas jembatan = 174.00 m2 Tebal beton = 0.120 m
Volume concrete slab = Luas jembatan x tebal beton
= 174.00 x 0.12
= 20.88 m3
Berat concrete slab = Vol. concrete slab x Bj Beton
= 20.88 x 2,400.00
= 50,112.00 kg
= 50.11 ton 3) Berat aspal
Luas jembatan = 174.00 m2 Tebal aspal = 0.05 m
Volume aspal = Luas jembatan x tebal aspal
= 174.00 x 0.05
= 8.70 m3
Berat aspal = Vol. aspal x Bj aspal
= 8.70 x 2,200.00
= 19,140.00 kg
= 19.14 ton
4) Berat trotoar
Lebar trotoar = 1.11 m Panjang trotoar = 11.60 m Tinggi trotoar = 0.25 m
Jumlah trotoar = 2.00 bh (kanan & kiri jembatan)
Volume trotoar = Lebar trotoar x panjang trotoar x tinggi trotoar x jumlah trotoar
= 1.11 x 11.60 x 0.25 x 2.00
= 6.44 m3 Berat trotoar = Volume trotoar x Bj beton
= 6.44 x 2,400.00
= 15,451.20 kg
= 15.45 ton 5) Berat concrete barrier
Lebar concrete barrier = 0.29 m Panjang concrete barrier = 11.60 m Tinggi concrete barrier = 0.70 m
Jumlah concrete barrier = 2.00 bh (kanan & kiri jembatan)
Volume concrete barrier = Lebar cocnrete barrier x panjang concrete barrier x tinggi concrete barrier x jumlah
= 0.29 x 11.60 x 0.70 x 2.00
= 4.71 m3
Berat concrete barrier = Volume concrete barrier x Bj beton
= 4.71 x 2,400.00
= 11,303.04 kg
= 11.30 ton
Total Beban Mati =
= 226.52 + 50.11 + 19.14 + 15.45 + 11.30
= 322.53 ton
b) Beban Hidup (QLL)
Luas jembatan = 174.00 m2 Beban lalu lintas = 1.50 ton/m2
Total Beban Hidup = Luas jembatan x beban lalu lintas Total Beban Hidup = 1.50 x 174.00
= 261.00 ton c) Beban Total (Qtotal) pada Voided Slab
QDL = 322.53
QLL = 261.00
Qtotal = QDL + QLL
= 277.42 + 261.00
= 583.53 ton
B. Pondasi Abutment 1 I. Material
Mutu beton = 450.00 kg/cm2
Fc' = 37.35 MPa
Ec (modulus elastisitas) = 28,723.88 MPa
Bj Beton = 2,400.00 kg/m3
II. Data Abutment 1
Lebar abutment = 15.00 m
B1 = 0.25 m
B2 = 0.80 m
H1 = 0.62 m
H2 = 0.70 m
Volume abutment = (B1 x H1 x lebar abutment) + (B2 x H2 x lebar abutment)
= (0.25 x 0.62 x 15.00) + (0.80 x 0.70 x 15.00)
= 10.73 m3
Berat abutment = Volume abutment x Bj beton
= 10.73 x 2,400.00
= 25,740.00 kg
= 25.74 ton III. Data Wing Wall
Lebar wing wall = 0.30 m
B wing wall = 2.50 m
Berat sendiri voided slab + berat concrete slab + berat aspal + berat trotoar + berat concrete barrier
H wing wall = 0.70 m Jumlah wing wall = 4.00 bh
Volume wing wall = Lebar wing wall x B x H x jumlah wing wall
= 0.30 x 2.50 x 0.70 x 4.00
= 2.10 m3
Berat wing wall = Volume wing wall x Bj beton
= 2.10 x 2,400.00
= 5,040.00 kg
= 5.04 ton
IV. Data Plat Injak
Lebar plat injak = 15.00 m B plat injak = 2.00 m H plat injak = 0.30 m Volume plat injak = Lebar plat injak x B x H
= 15.00 x 2.00 x 0.30
= 9.00 m3
Berat plat injak = Volume plat injak x Bj beton
= 9.00 x 2,400.00
= 21,600.00 kg
= 21.60 ton
V. Beban yang Bekerja pada Abutment 1
Abutment 1 menerima 1/2 dari beban total pada voided slab
Q abutment = berat sendiri abutment + 1/2 x Qtotal voided slab
= 25.74 + 1/2 x 583.53 Q abutment = 317.50 ton
VI. Tinjauan Terhadap Beban Tetap
Beban yang diterima oleh 1 buah pondasi pilecap jembatan adalah:
Q abutment = 317.50 ton
Q wing wall = 5.04 ton Q plat injak = 21.60 ton
Pa = Q abutment + Q wing wall + Q plat injak
= 317.50 + 5.04 + 21.60
Pa = 344.14 ton
Digunakan pondasi bored pile diameter 40cm dengan spesifikasi berikut:
Diameter (D) = 0.40 m
Luas penampang = 1,256.00 m2
P ijin bored pile = 60.00 ton
Safety factor = 2.50 Kebutuhan Bored Pile untuk Abutment 1:
Pa' = Pa x safety factor
= 344.14 x 2.50
Pa' = 860.36 ton
N Bored Pile = Pa' / P ijin bored pile
= 860.36 / 60.00
= 14.34 nos N Bored Pile digunakan = 15.00 nos
Jarak antar bored pile (S) = 2D ≤ S ≤ 3D
= 2 x 0.40 ≤ S ≤ 3 x 0.40
= 0.80 ≤ S ≤ 1.20 S digunakan = 1.00 m
Kebutuhan panjang area pondasi
L pondasi = S x (N bored pile -1)
= 1.00 x (15 - 1) L pondasi = 14.00 m Cek, apakah lebar pondasi < lebar jembatan:
L pondasi < Lebar jembatan 14.00
< 15.00 OK!!
Gambar hasil desain pondasi jembatan:
TAMPAK ATAS PENAMPANG ABUTMENT 1
TAMPAK ATAS PENAMPANG ABUTMENT 2
Jadi, berdasarkan perhitungan yang telah dilakukan pada abutment 1, dapat digunakan pondasi bored pile diameter 400mm dengan jumlah 15.00 nos untuk satu abutment.
TAMPAK ATAS JEMBATAN
POTONGAN A-A
POTONGAN B-B
