analisis stabilitas tiang -eng

8/20/2019 Analisis Stabilitas Tiang -EnG

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References:

Coduto, D.P. (1994): Foundation design: principles and

practices

Day, R.W. (2010): Foundation engineering handbook

Hardiyatmo, H.C. (2011): Analisis dan Perancangan

Fondasi, Bagian II

Teng , Wayne C. (1992): Foundation Design

Tomlinson, M.J. (2001): Foundation design and

construction

Deep Foundation


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Topics (from SAP):Kapasitas dukung tiang terhadap gaya lateral

dalam tanah kohesif

a. Ujung tiang bebas (tiang pendek dan tiang panjang)

b. Ujung tiang terjepit (tiang pendek dan tiang panjang)

Defleksi tiang a. Ujung tiang bebas (tiang pendek dan tiang panjang)b. Ujung tiang terjepit (tiang pendek dan tiang panjang)

Analisis stabilitas fondasi tiang

a. Beban tiang

b. Kapasitas dukung tiang

c. Jumlah tiang

d. Susunan tiang

e. Kontrol

Turap

a. Pengertian

b. Tipe struktur turap

c. Tipe turap dari segi bahan

Perancangan turap jenis kantilever

a. Gaya-gaya yang bekerja

b. Panjang turap yang dipancang

c. Dimensi turap dan pemilihan profil turap

Perancangan turap dengan angkur

a. Letak tumpuan angkur

b. Dimensi batang angkur

c. Konstruksi angkur

Fondasi caisson

a. Pengertian dan jenis fondasi caisson

b. Bentuk tampang fondasi sumuran

c. Analisis fondasi sumuran


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Basic principle of Pile Foundation Design

a. Load

• Vertical load (downward/upward)• Lateral load

• Moment

Type of structural load :• Dead load relatively constant over time, including the

weight of the structure itself, and immovable fixtures

• Live load temporary, of short duration, or moving. These

dynamic loads may involve considerations such as impact,momentum, vibration, slosh dynamics of fluids, fatigue, etc.

• Environmental load act as a result of weather, topography

and other natural phenomena (


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Design of Pile Foundation

b. Bearing capacity of the pile

• Dead loadPa : Axial load capacity (downward)

T a : Axial load capacity (upward)

Ha : Lateral load capacity

• Live load / Environmental load

Pas = 1½ PaT as = 1½ T a


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c. Number of pile

Based on dead load

V : Vertical load

Pa : Allowable axial load capacity

n : number of pile

d. Pile arrangement

By trial and error

• Pile distance > minimum distance

• The center of pile group is located at the load resistance point

a P

V n

Design of Pile Foundation


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Example:

An upper structure is made by reinforced concrete, with the

sectional size of 2,0 m x 2,0 m, and 20 m high. Pile foundation isused with the thickness of pile cap = 1,0 m, pile head on the ground

surface. Seismic coefficient = 0,10.

Allowable bearing capacity of the pile (based on soil characteristic)

• Pa = 400 kN/pile dead load

• T a = 100 kN/pile dead load

• Ha = 10 kN/pile dead load

Unit volume weight of concrete ( concrete) = 25 kN/m3

Design the pile foundation.


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Solution:

a. Considering dead load

Construction weight, P1 = 222025 = 2000 kN

Assumed Pile-cap weight, P2 = 250 kN

Total vertical weight, V = P1 + P2 = 2250 kN

Number of pile use 6 piles

The seismic load may act to every direction, therefore

symmetrical piles is considered.If pile-cap is square use 8 piles.

6,54002250

a P V n


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Control of the pile-cap weight

Pile-cap weight

= 331 m325kN/m3 = 225 kN

P1 = 2000 kN

Pile-cap load = 225 kNV total = 2225 kN

p (=287,12 kN) < Pa (= 400 kN)

The foundation can be used

kN128,278

8

2225

n

V p

P1=2000 kN

O

0,5

O

0,5

0,5 0,5

1,0

1,0

1,0

1,0 1,0


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b. Control by the seismic load

Seismic load is calculated as the weight of upper structure,

working on the center weight of the structure.

Upper structure weight:

= 2225 kN = 2000 kN

Seismic load (H):

= 0,12000 = 200 kN

(center weight is working at 10 m

above the ground surface)

20 m

1 m

P2

P1

H

10 m


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Conclusion:

• Due to dead load OK

• Control by seismic load NOT OK

• Increase the pile distance (moment arm)

Pile-cap weigth

= 3,53,5125 = 306,25 kNV = 2000 + 306,25 = 2306,25 kN

H = 200 kN

M = 2200 kN m

x 2 = 3(-1,25)2 + 3(+1,25)2 = 9,375 m2

0,5

O

0,5

0,5 0,5

1,25

1,25

1,25 1,25

IIIIII


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Dead load

< Pa (= 400 kN)

Seismic load

< 1,5 Pa (downward)

< 1,5 T a (upward)

Conclusion :

The pile foundation arrangement can be applied to support dead

load and seismic load

kN28,288

8

25,2306

n

V p

kN615,581

375,9

25,12200

8

25,2306III)(columnmaks

p

kN052,5

375,9

25,12200

8

25,2306I)(columnmin

p


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Control by the lateral load due to earthquake

Without inclined pile : Ht = H

For each pile : > Ha= 10 kN

The use of inclined pile is considered

Inclined pile of number: 2, 5, 4, 7

Pile inclination 1 : m = 1 : 4

kN258

200 n

H h t t

0,5

O

0,5

0,5 0,5

1,25

1,25

1,25 1,25

1 2 3

4 5

6 7 8

1

4


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Col I : ( )

( )

< 1,5 T a OK

Col II : (no inclined piles)

( )

Col III : ( )

( )

< 1,5 Pa OK

kN052,5614 P P V

kN263,14

052,544

m

V

H

kN43,41 244 mm

V P

kN28872 n

V V V

kN14555 n

V H

kN581853 P V P

kN5991 255 mn

V P


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Lateral load

= 200 + (-1,263 – 145,404) = 53,333 kN

< Ha= 10 kN

Conclusion: the group pile arrangement could support the horizontalload.

NOTE:Seismic load may work to every direction, therefore the inclined

pile is designed symmetrical to both X and Y axes.

it H H h

kN667,68333,53

n H h t t

analisis stabilitas tiang -eng

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