Perencanaan Tebal Perencanaan Tebal PerkerasanPerkerasan

METODE AASHTOMETODE AASHTO

METODE AASHTOMETODE AASHTO Rumus umum:Rumus umum:

Log Wt18 = 9.36 log (SN+1)-0.20+Gt/(0.40+(1094/(SN+1)Log Wt18 = 9.36 log (SN+1)-0.20+Gt/(0.40+(1094/(SN+1)5.195.19))))

+log (1/R) + 0.372(Si-3)+log (1/R) + 0.372(Si-3)

Dimana:Dimana: Wt18 = beban lalin selama UR atas dasar beban 18 kips yang Wt18 = beban lalin selama UR atas dasar beban 18 kips yang diperhitungkan terhadap faktor regionaldiperhitungkan terhadap faktor regional Gt = log (4.2-Pt)/(4.2-1.5)Gt = log (4.2-Pt)/(4.2-1.5) Si = soil support (korelasi CBR) (Bina Marga = DDT)Si = soil support (korelasi CBR) (Bina Marga = DDT)

R R = faktor regional (Bina Marga = FR) = faktor regional (Bina Marga = FR)SNSN = structural number (Bina Marga = ITP) = structural number (Bina Marga = ITP)

Soil SupportSoil Support

Punya korelasi dengan CBRPunya korelasi dengan CBRsubgradesubgrade

Gunakan GrafikGunakan Grafik CBR CBR skala log skala log Si Si skala linear skala linear

1 2 3 4 5 10 50 100 200

1.01.0 2.02.0 3.03.0 4.04.0 5.05.0 6.06.0 7.07.0 8.08.0 9.09.0 10.010.0

Soil Support Value (Si)Soil Support Value (Si)

California Bearing Ratio (CBR)California Bearing Ratio (CBR)

Regional FactorRegional Factor

Roadbed material frozen to depth of 0.2 Roadbed material frozen to depth of 0.2 to 1.0to 1.0

5” (130 mm) or more5” (130 mm) or more Roadbed material dry, summer and fall 0.3 Roadbed material dry, summer and fall 0.3

to 1.5to 1.5 Roadbed material Roadbed material wetwet, , spring thawspring thaw 4.0 to 4.0 to

5.05.0

Percentage of Vehicle Percentage of Vehicle Concentration (C)Concentration (C)

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36

Total Volume in One Direction-hundreds of vehicle/hour

C (

%)

Percentage that commercial vehicle were of total traffic both lane

Passenger cars in left lane

Commercial vehicle in left lane

Structural Layer Structural Layer CoefficientsCoefficients

Pavement Component Coefficient (ai)

SURFACE COURSE- Road Mix (Campuran di jalan), low stability 0.20- Plant Mix (AMP), high stability 0.44- Sand asphalt 0.40BASE COURSE- Sandy gravel 0.07- Crushed stone 0.14- Cement treated base 0.15-0.23- Bitumeous Treated (ATB&ATBL) a. coarse graded 0.34 b. sand asphalt 0.30- Lime treated (campuran kapur & batu) 0.15-0.30SUB BASE- Sandy gravel 0.11- Sand or sandy clay 0.05-0.10

Contoh:Contoh:PerhitungaPerhitungan EDFn EDFdari data dari data LoadometeLoadometerr

Axle Load Group (lbs)

Representative Axle Load, Lbs

Equiv. Factor

No. Of Axles

Equiv. 18 kip Single Axles

single axlesunder 3000 2000 0.0003 512 0.23000-6999 5000 0.012 536 6.47000-7999 7500 0.0425 239 10.28000-11999 10000 0.12 1453 174.412000-15999 140000 0.4 279 111.616000-18000 17000 0.825 106 87.518001-20000 19000 1.245 43 53.520001-21999 21000 1.83 4 7.322000-23999 23000 2.63 3 7.924000 and over 0 0.0

Sub total 458.9tandem axlesunder 6000 4000 0.001 9 0.06000-11999 9000 0.008 337 2.712000-17999 15000 0.055 396 21.818000-23499 21000 0.195 457 89.124000-24999 27000 0.485 815 395.330000-32000 31000 0.785 342 268.532001-33999 33000 1 243 243.034000-35999 35000 1.245 173 215.436000-37999 37000 1.535 71 109.038000-39999 39000 1.875 9 16.940000-41999 41000 2.275 0 0.042000-43999 43000 2.74 1 2.744000 and over 0 0.0

Sub total 1364.31823.2

Total all trucks = 3146Pt = 2.5 SN = 3

Total

Contoh:Contoh:Perhitungan EDFPerhitungan EDFdari data Loadometerdari data Loadometer

Rata2 per truck = 1823.2/3146 = (0) 0.579529561 (18 kip beban sumbu)ADT awal = (1) 4000 kend/hariADT 20 th = (2) 6000 kend/haripersen truk = (3) 20% dari ADTADT rata2 = [ (1)+(2) ] / 2 = (4) 5000 kend/hariUR 20 th

ADT perlajur = (4) / 2 = (5) 2500 kend/hari

ADTT rata2 = 500 kend/hari

Jumlah truk = (6) * 365 * 20 = (7) 3,650,000 trukselama 20 th

Jumlah EAL = (7) * (0) 2,115,282.90 18 kip beban sb standar

Contoh:Contoh:Perhitungan Tebal Perkerasan Cara Perhitungan Tebal Perkerasan Cara AASHTOAASHTO- 4/2D Highway

- UR = 20 th- ADT awal = 18608 vehicle- Jumlah truk = 14% ADT- Pertumbuhan = 2%- Fakt. Reg = 1- Data Traffic- Asumsi SN Awal = 3

Axle load groups

Representative axle load

Equivelent factorNo. of axles

per 1000 trucks

Equivalent 18 kip single axle per

1000 truckssingle axles

under 3 2 0.0003 426.8 0.133-7 5 0.012 669.6 8.047-8 7.5 0.0425 228.2 9.70

8-12 10 0.12 678.8 81.4616-18 14 0.4 230.9 92.36

28-30 29 6.92 0.19 1.31Total 551.30

tandem axlesunder 6 4 0.001 0.38 0.00

6-12 9 0.008 169 1.3512-18 15 0.055 153.6 8.4518-24 21 0.195 139.4 27.1824-30 27 0.485 191 92.6430-32 31 0.795 55.3 43.96

52-54 59 6.25 0.19 1.19Total 365.41

EAL 18 kip = 551.3 + 365.41 = 916.71 per 1000 truck

Dari perhitungan ADTi = 0.02 ; n = 20 th

Design ADT = 1/n (ADT) [(1+i) n̂ - 1]/(ln (1+i)) = 1/20 (18608) [(1+2%) 2̂0 - 1]/(ln (1+2%)) = 22832 kendaraan/2 arah

Design ADT per arah 11416 kendaraan/hari

Jumlah kendaraan per jam untuk satu arah = 476 kend/jam(Vph) --> 90 % (lihat gambar 1)ADTT = 1598 trucks

ADTT pada lajur rencana = 1438 kend.

EAL = 1438*916.71/1000 = 1319

EAL UR 20 th = 9,625,682 EAL

Log Wt 18 = 6.98

Misal:CBR subgrade = 3%Si = 3CBR subbase = 30%Si = 6.8CBR base = 100%Si = 8.8

Tebal perkerasan diatas subgrade: Tebal perkerasan diatas subbase: Tebal perkerasan diatas base:

CBR=3% CBR=30% CBR=30%Pt=2.5 Pt=2.5 Pt=2.5R=1 R=1 R=1LogWt18=6.98 LogWt18=6.98 LogWt18=6.98

Masuk rumus umum!!! Masuk rumus umum!!! Masuk rumus umum!!!

didapat SN = 5.55 didapat SN = 3.45 didapat SN = 2.47

jadi: a1D1+a2D2+a3D3 = 5.55 jadi: a1D1+a2D2 = 3.45 jadi: a1D1 = 2.47

D2,a2

D1,a1

D3,a3

Rumus umum:Rumus umum:Log Wt18 = 9.36 log (SN+1)-0.20+Gt/(0.40+(1094/(SN+1)5.19))

+log (1/R) + 0.372(Si-3)