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
= 94.38 x 2,400.00
= 226.518,86 kg
= 226,52 ton 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
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
Berat sendiri voided slab + berat concrete slab + berat aspal + berat trotoar + berat concrete barrier
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
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
TAMPAK ATAS JEMBATAN
Jadi, berdasarkan perhitungan yang telah dilakukan pada abutment 1, dapat digunakan pondasi bored pile diameter 400mm dengan jumlah 15.00 nos untuk satu abutment.
POTONGAN A-A
POTONGAN B-B
