Foundations of High Rise Buildings - JEA Conferences€¦ · Foundations of High Rise ... Civil Engineering Conference (JICEC06) Subsoil ... raft in difficult geological conditions

prof. Dr. Ing. Yasser El-Mossallamy 1

Professor Yasser El-Mossallamy

Slide: 1

The Sixth Jordanian International Civil Engineering Conference (JICEC06)

Foundations of High Rise Buildings

Prof. Dr.-Ing. Yasser El-Mossallamy

Professor of Geotechnical Engineering

Ain Shams Univ. Cairo, Egypt

c/o Arcadis Consult, Germany

[email protected]


Slide: 2


Development of High-rise Buildings in city centers

Frankfurt New York

Hongkong Dubai



Slide: 3


Development of High-rise Buildings in city centers

Although the cost of the foundation of a high rise

building is only a small fraction of the total cost

(about 10 to 15%), the foundation is one of the main

design elements, which affects the whole behaviour

of the building.

On the other hand, the construction time of the

foundation and basement floors takes about 30 to

50 % of the total construction time.

These conditions make the foundation of high rise

buildings one of the most critical construction items

regarding the risk assessment analyses and

optimization of construction schedule.


Slide: 4


Different foundation types

Raft foundation

100 m

1

2

Piled raft

256 m

1

2

Piled foundation

259 m

1

2

Relatively incompressible soil

Compressible soil 1

2



Slide: 5


The Main Concept of Piled Raft

m

D

Q

b

qsjPl

Pk

L

Qt

qsj PlPk

Traditional pile foundation

Piled raft foundation

S

1.0

a L : Pile load share

0,0

0.5

0.2 0.4 0.6 0.0 0.8

0.0

1.0

a L P t = Q / Q

a

Settlement of piled raft

Settlement of corresponding raft a

S =

foundation Traditional raft


Slide: 6


Interaction aspects

X

YZ

Q

Q Q

D

P,i,1 P,i,m

t

Z

Raft/soil Raft/Piles

Pile/SoilPiles/

Piles

Pile/Soil

a a

s s

(x,y)

Q =

(x,y) dA

Raft

dAy)(x,=Q Raft

ni

1i

ip,Piles Q=Q n : No. of piles



Slide: 7


Frankfurt as an example for development of foundations on compressible subsoil


Slide: 8


b) load share

Torhaus Messe Frankfurt

c) Pile loads dependent on pile position



Slide: 9


Messeturm, Frankfurt

a) View

58.8m

58.8

5.0

9.0

G.W.T

3.0

Outer pile ring

Middle pile ring

Inner pile ring

b- Longitudinal section of the foundation

c- Cross section of the tower above the foundation

Totalstructuralload=1880MN

6.0m

d) Load share


Slide: 10


e) Skin friction and pile forces dependent on depth

Messeturm, Frankfurt



Slide: 11


How we measure:

DG Bank, Frankfurt

89.9 m

38.4

m6

4.5

m

47.5 m

NSettlement joint

I

I

Main tower

Main tower

Side building

+ 60

14,5 m

30 m

Quaternary

Frankfurt clay

Section

Plan

Inner core

208 m

47

.5 m

64.5 m

SDG 1

EXT / INK II

EXT / INK I

EXT III

SDG 2

SDG 3

SDG 4

SDG 5

SDG 6

SDG 7

PWD 1

Settlement joint

PWD 2

PWD 3

PWD 4

PWD 5

SDG 8

SDG 9

SDG 10

SDG 11

SDG 12

SDG 13

P V P III

P II

P IV

P I

P VI


Slide: 12


Instruments, Pile load cell



Slide: 13


Measuring raft contact stresses

DG Bank, Frankfurt


Slide: 14


Measuring water pressure beneath the raft

DG Bank, Frankfurt



Slide: 15


Load-settlement behavior of piled raft, Load-time development

DG Bank, Frankfurt

0

0.1

0.2

0.3

0.4

0.5

0.6

0 500 1000 1500 2000 2500 3000 3500

Time [days]

DG Bank

a L

0

0.1

0.2

0.3

0.4

0.5

0.6

0 500 1000 1500 2000 2500 3000 3500

Time [days]

DG Bank

a L

Development of pile load share with time


Slide: 16


Instruments, Measuring room



Slide: 17


Numerical analysis of piled raft

Finite diference method

(FDM)

Finite element method

(FEM)

Boundary element method

(BEM)

- One dimensional analysis

(Load transfer method)

- Two and three dimensional

analysis

- One dimensional analysis

- Two dimensional analysis

Plane strain

Axisymmetry

- Three dimensional

analysis

- Using superposition

technique

- Complete boundary element

structure

- Hain and Lee (1978)

- Hybrid model (O'Neill et al. 1981)

- Modified hybrid model (Chow 1986)

- El-Mossallamy (1996)

Mixed technique

Mathematical procedures


Slide: 18


Comparison between observed and calculated behavior of piled raft

0

4

8

12

16

20

24

L oad [MN]

0 4 00 8 00 1 200

Calculated undrained

Calculated, drained

16 00

Observed behavior

(a)

(b)

(b) E nd of construction

(a)1 year after end of construction

0

4

8

12

16

20

0 4 00 8 00

0

4

8

12

16

20

0 4 00 8 00

L oad [MN] L oad [MN]

a- Total load

b- Pile load share c- Raft load share

Observed behavior

Calculated, drained

Observed behavior

Calculated, drained

Set

tlem

ent

[cm

]



Slide: 19


Different load settlement relationships

0

4

8

12

16

20

24

0 4 8 12 16 20

(1)

(2)

(3)

(4)

Load [MN]

Domain of measured pile loads

Legend

(1) Single pile,

(2) Average behaviorof the same pile as a member

of an equally loaded free standinggroup,

(3) Average behaviorof the same pile as a member

of the pile group below the raft of the DG Bank

(piled raft foundation)

(4) The observedaverage behaviorof

the piled raft piles.

Set

tlem

ent

[cm

]


Slide: 20


(2) Observed

(1) Calculated

Skin friction (kN/m²)

0 40 80 120 160

0

6

12

18

24

30

Normal force (MN)

0 3 6 9 12

0

6

12

18

24

30

15

Depth

(m

)

(1)

(2)(1)

(2)

Development of pile skin friction by piled raft



Slide: 21


Comparison between measured and calculated settlement

Main Tower Side buildings

Settlement joint

1

2

3

0

4

8

12

16

20

Settlement trough along section I - I

1 Measurements , piled raft 2 Calculation , piled raft

3 Calculation , raft without piles

I I

Settlement joint

Sett

lem

en

t [c

m]


Slide: 22


Distribution of bending moments of the piled raft and of the corresponding

raft without piles

Main tower Side buildings

1

2

Settlement jointSettlement joint


1

2



1

2




Slide: 23


Contour lines of normalized vertical stresses beneath the center line of the piled

raft and of the corresponding raft without piles

0 . 0

0 . 1

0 . 2

0 . 3

0 . 4

0 . 5

0 . 6

0 . 7

0 . 8

0 . 9

1 . 0

n

0 . 1 0 . 2

0 . 3 0 . 4 0 . 5

0 . 6

0 . 7

0 . 8

0 . 9

0 . 1 0 . 2 0 . 3

0 . 4

0 . 5

0 . 6

0 . 7

0 . 4 0 . 3

Main Tower Side Building


Settlement joint

n = z

o :Normalized vertical stresses

:Vertical stresses

:Average applied stresses of the main tower

n

z

o

Main Tower Side Building

Conventional raft foundation


Slide: 24


Features of piled raft behavior:

- Pile behavior depends on pile position

- Pile capacity is completely difference than that of corresponding single pile

- Skin friction develops from pile tip to pile top

- Fewer number of piles can decrease the settlement significantly

- Pile arrangement within pile group beneath the structural elements can

reduce the raft internal stresses significantly. This has an effect on the

reinforcement grad, on the raft thickness, on the required excavation depth,

on the design of the required shoring system and on the required dewatering.



Slide: 25


Application of piled raft in calcareous sand

Foundation of High Rise Building (Kuwait)

Salimia, El-Mossallamy et al.


Slide: 26


Subsoil conditions





Slide: 27


Traditional deep foundation of the high-rise building Salimia, Kuwait

624 piles with 0.9 m diameter


Pile length = 22 m




Slide: 28


Behavior of calcareous sand

Silica sand

Calcareous sand

Silica sand

Calcareous sand



Slide: 29


Results of pile load tests in Calcareous sand




Slide: 30


Proposal of an optimized piled raft for the high-rise building Salimia, Kuwait



Pile length = 17 m





Slide: 31


Comparison between traditional piled foundation and piled raft foundation

Traditional deep foundation Piled raft foundation

Total no. piles 1085 396

Pile diameter 0.9 and 0.6 1.2 and 0.6

Pile length 22 m 17 m

Total length of piles 23870 m 6732 m




Slide: 32


Application of piled raft in difficult geological conditions

Foundation of High Rise Building (Jabal Omar Complex Makkah, Saudi Arabia)



Slide: 33




Design aspects:

1- Foundation partially on soil, partially on rock

2- High earth pressure (30 m height)

3- Unequal earth pressure


Slide: 34






Slide: 35


36.9

m

52.7 m

115.3

0.0 = 98.9 mNN

Q

T

GW

-15.8 m

-23.4 m

-37.8 m

a) Cross section

b) Plan

Q = Quaternary Sand/Gravel

T = Tertiary clay

Plaxis 3D Foundation

Case history: Japan Center


Slide: 36


Embedded piles

Embedded piles:

soil

pile

tskin

Ffoot



Slide: 37


3D FE-Model


Slide: 38


Loads



Slide: 39


Loads


Slide: 40


Graphical presentation of the piles in different working planes



Slide: 41


3D FE-Model


Slide: 42


Axial strain 1

(

50E

1

Asymptote

Failure line

urE

1

qf

qa

0 2 4 6 8 10 12 14 16

0

300

600

900

1200

1500

De

via

tori

c s

tre

ss (

Axial strain 1

FEM results

Test resultsCD - Triaxial test

= 400 KN/m²3

= 100 KN/m²3

= 200 KN/m²3

Hardening soil model

g g

f

n

/ ’

’ = 29° = 0,0

= 20 / 10 kN/m³

E = 30 MN/m² w = 1,0

c = 40 kN/m² E = 90 MN/m²

= 0.2 R = 0.9

’

f

ref

ref

50ref

ur

Applied Constitutive Law



Slide: 43


Table 1: Geotechnical parameters a- Hardening soil mode Soil parameter Filling Quaternary

Sand/Gravel

Overconsolid

ated clay

E ref

50 [MN/m

2] 20 30 35

Eur

ref [MN/m

2] 50 75 105

ur [-] 0.2 0.2 0.2

m [-] 0.5 0.5 1.0

Rf [-] 0.9 0.9 0.9

/ ´ [kN/m3] 18/8 19/11 20/10

kx [m/sec] 10-3

10-3

2.5 x 10-5

ky [m/sec] 10-3

10-3

0.01 kx

c´ [kN/m2] - - 20

´ [°] 30 35 20

Ko [-] 0.5 0.43 0.8

where:

Eref50 Primary loading stiffness

Eurref

Unloading/reloading stiffness

ur Unloading/reloading Poisson’s ratio

m Power in stiffness laws

Rf Failure ratio

/ ´ Total / Effective unit weight of soil

c´ Cohesion

´ Angle of internal friction

Ko Coefficient of earth pressure at rest

kx, ky Permeability coefficient in the

horizontal and vertical direction

b- Mohr-Coulomb model Soil parameter Limestone

E [MN/m2] 750

[-] 0.3

/ ´ [kN/m3] 20/10

kx [m/sec] 10-3

ky [m/sec] 10-3

c´ [kN/m2] 200

´ [°] 35

Structure elements Piles:

E concrete = 30000 MN/m² and = 0.2

Anchor tendons:

E steel = 195000 MN/m²

Soil parameters


Slide: 44


Foundation settlement under working loads

Set

tlem

ent

(cm

)

obs. 1obs. 1obs. 1

Set

tlem

ent

(cm

)

obs. 1obs. 1obs. 1



Slide: 45


Piled raft of Minaret


Slide: 46


Geological conditions (Rock surface contour lines



Slide: 47


Geological Sections


Slide: 48


Finite element model

Alluvium deposit Alluvium deposit

Igneous rock



Slide: 49


Page 49

Foundation model

Igneous rock


Slide: 50


Piled raft of Minaret

Igneous rock



Slide: 51


Raft Settlement

Max. settlement = 37.1 mm


Slide: 52


Raft Settlement

Max. settlement = 37.1 mm



Slide: 53


Page 53

Pile Stiffness (MN/m)


Slide: 54




Slide: 55


Tank cross section

Embedded piles for large tanks on soft soil

No. of piles = 376

Pile diameter = 1.5 m


Slide: 56





Slide: 57




Slide: 58


58

INFOGRAPH – Calculation

- 3-dim. finite element analysis

- Structural system modeled as an overall system

- Dynamic analysis


a(T)

0,000

0,100

0,200

0,300

0,400

0,500

0,600

0 0,5 1 1,5 2 2,5 3 3,5 4



Slide: 59




Slide: 60




Slide: 61



Slide: 62


Design concept of piled rafts

Model Simulation

soil-structure interaction

Lab testing (e.g.

Triaxial tests)

Field tests(e.g. SPT)

Optimization analysis

- economic conditions

- serviceability

requirements

Back-calculation

Comparison

Structural design

Foundation design

• Serviceability limit state

• Ultimate Limit state

Determine the required structural parameter

1- pile stiffness depending on pile position

2- soil subgrade reaction modulus for the raft

Soil model

Geo

tech

nic

al

eng

inee

rsS

tru

ctu

ral

eng

inee

rs

Pile load test,

Prototype



Slide: 63


Application of piled raft


Foundation on medium to dense sandFoundation on overconsolidated clay

Foundation on heterogeneous subsoil,

uncoupled piled raftFoundation on soft clay

Raft

Compacted

soil

Raft

Compacted

soil

0

0

0

200

400

600

800

1000

1

2

3

Set

tlem

ent

(cm

)T

ota

l ap

pli

ed l

oad (

MN

)

Time

1.7.97 1.1.98 1.7.98 1.1.99 1.7.99 1.1.00

0

0

0

End of basic

construction

Final

construction

G.S. = 423.3 müM

GW cal.= 421.0 müM

403.0 müM

388.8 müM

Foundation = 420.52 müM

0.5 m

Moraine

High plastic clay

Middle plastic clay

ABCDEFGHIJ

Section 8-8

High shelves

Piles

17.0

m1

4.0

m

°

°

Tower

Neighboringbuilding

Neckar Street

Kaiser Street

Side building

Gallusa

nla

ge

Neighboringbuilding

Conclusion / Résumé


Slide: 64


Aim of piled raft


Optimizing the foundation designControlling the settlement

Increasing the bearing capacity

slip lineneglected

pile existence neglected

a) Prandtl zone for complete free flow failure

b) Assumed block failure with free flow at the pile base area

g t

t

F

F

Conclusion / Résumé



Slide: 65


Documents

Foundations of High Rise Buildings - JEA Conferences€¦ · Foundations of High Rise ... Civil Engineering Conference (JICEC06) Subsoil ... raft in difficult geological conditions