Bullet31 TAW Budapest 05 - FenixEdu · e=0.12 e=0.16 e=0.12 4.00 3.30 2.87 7 6 SECTION A-A 6' 1.62 0.53 2.24 4.75 5 4 1.00 3 3.05 0.16 0.25 0.22 2. 1.36 0. 1 2 fp0.1k > 1670 MPa fpuk

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fib Symposium “Keep concrete attractive” Budapest 2005fib Symposium “Keep concrete attractive” Budapest 2005

Post-tensioning in buildingsPostPost--tensioning in tensioning in buildingsbuildings

fib Commission 1 “Structures”

Task Group 1.1 “Design Applications”

WP 1.1.2 – Post-Tensioning in Buildings

J. Almeida, LisbonJ. Camara, LisbonH. Corres, MadridT. Friedrich, ZurichM. Miehlbradt, LausanneJ.-M. Voumard, BernB. Westerberg, Stockholm

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Design teamArchitecte

Structural Designer.......

Contractor

Owner

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The potential offered by prestressing is not fully exploited in building structures field.

more architectural freedom / functional advantages

22.14m

St. Gabriel Tower, Lisbon

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longer spans / improved flexibility

Parking deck “GAD Munsten”, Switzerland Spans 16.0m x 7.5m

BNC Headquarters, LisbonSpans (4.2m + 11.7m + 4.2m) x 8.1m


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slender and lighter floor systems


Fuenlabrada Shopping Center, Spain Spans 12.0m x 12.0mt = 0.32m (0.32m to 0.55m)

BNC Headquarters, LisbonSpans (4.2m + 11.7m + 4.2m) x 8.1mt = 0.22m (0.22m to 0.40m)

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Reduced construction time.


Nestle Distribution Center, ChileSlab on ground 150m x 220mConstruction time ≈ 2 months

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substantial reduction in the total steel area. ⇒ improved details and easier placing and compacting of concrete.

CORE FOOTINGTENDONS LAYOUT

CORE FOOTING

12A2

3

0.25

1

2 2A

3

3Ø25

Ø32//0.20

Ø32//0.20

Ø25//0.20

Ø25//0.20

Ø25//0.20

13

1

1

3

3

3

3

1

1

3

3

3

3

1

1

13

3

3

3

Ø25//0.20

Ø25//0.20

Ø32//0.20

LONGITUDINAL SECTION

Ø32//0.20Ø25//0.20

2A

2

2 layers Ø40//0.20

1

Ø25//0.20

2

2A

2

2A

2A

2

2A

1

1

1

1

2

2

2A

2A

1

1

1 2A

Ø25//0.20

3Ø25


St. Gabriel Tower – footing, LisbonFsd,u ≈ 21 000 kN/m

S500 (2 layers φ40//0.20) – 25 % total Asprestressing steel – 75 % total As

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In many cases in which post-tensioning would provide a visibly superior solution, it happens that a more conventional non-prestressed solution is often selected.


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2 POST-TENSIONING IN BUILDINGS2.1 General2.2 Basic concepts of prestressing2.3 Design aspects2.4 Technology of Prestressing in Building

P P

q

q

Pq

a) Axial effect only

b) Eccentric axial effect

c) Axial and transverse effect

P q P+q

Tens

ion

Com

pres

sion

0 0 0

Pee

P

Pe e

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2 POST-TENSIONING IN BUILDINGS2.1 General2.2 Basic concepts of prestressing2.3 Design aspects2.3.1 Structural effects and tendon profiles2.3.2 Prestressing force2.3.2.1 Maximum prestress2.3.2.2 Losses of prestress2.3.3 Serviceability limit states (SLS)2.3.4 Ultimate Limit States2.3.5 End anchorage and intermediate anchorages2.3.6 Structural Restraints

L

No significant restraintMax. movement ≈ prop. to L/2

No significant restraintMax. movement ≈ prop. to L

Significant restraint forcesSmall movements

“Wherever the axial effects of the prestress end up, the transverse effects will always act fully on the prestressedmember, and can be accounted for in every aspect of design.“

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2 POST-TENSIONING IN BUILDINGS2.1 General2.2 Basic concepts of prestressing2.3 Design aspects2.4 Technology of Prestressing in Building2.4.1 The Monostrand Post-Tensioning System - Unbonded and Sheathed Strand2.4.2 The Bonded Slab Post-Tensioning System2.4.2.1 The Monostrand System2.4.2.2 The Multistrand System2.4.3 Stressing Equipment and Clearance2.4.4 Installation2.4.5 Fire resistance2.4.6 SpecificationsAnnex: Specification Example

Bare strandsCement grout

H =21 mmB= 75 mm

B

HFlat steel duct

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15 mm 160 105x75100 110 75

[mm]

100

Strand type

13 mm

XrX

150 90

Anchor dim.YrY

70 110x70

XXr

Y Yr

X

2 POST-TENSIONING IN BUILDINGS2.1 General2.2 Basic concepts of prestressing2.3 Design aspects2.4 Technology of Prestressing in Building2.4.1 The Monostrand Post-Tensioning System with Unbonded and Sheathed Strand2.4.2 The Bonded Slab Post-Tensioning System2.4.2.1 The Monostrand System2.4.2.2 The Multistrand System2.4.3 Stressing Equipment and Clearance2.4.4 Installation2.4.5 Fire resistance2.4.6 SpecificationsAnnex: Specification Example

A

B

C

Centre hole jack Twin ram jack

A [mm] B [mm] 2 strand jack 2 strand jack 4 strand jack

C [mm] rectangular anchor 4 strands 5 strands

square or circular anchor 1 strand 2 strands 4 strands

950 - 1100 70 - 90

110 130

280 400

70 105 115

700 - 1200

60 - 80 - -

300 400

- - -

Anchorage space requirements

Jack clearance requirements

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1 INTRODUCTION2 POST-TENSIONING IN BUILDINGS

3 POSTENSIONED FLOORS3.1 Conceptual design3.2 Applications4 POSTENSIONED FOUNDATION4.1 Conceptual design4.2 Applications5 POSTENSIONED TRANSFER SLABS AND BEAMS5.1 Conceptual design5.2 Applications6 PREFABRICATED POST-TENSIONED SOLUTIONS6.1 Conceptual design6.2 Applications

The document covers the more common practical applications in concrete buildings

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N N

PP

0

Nsσ

σsN+P

090% of N balanced

60% of N balanced

0% of N balanced

4 POSTENSIONED FOUNDATION4.1 Conceptual design4.1.1 Influence of stiff elements and subgrade friction4.1.2 Raft foundations4.1.3 Post tensioned slab on ground4.2 Applications

0

10

20

0 25 50 75 100 125 150

Bearing Pressure, kPa

L/h

P/A = 0 MPaP/A = 1 MPaP/A = 2 MPa

Basic Concepts

Raft foundations - Preliminary Design

Slabs on ground – Design Criteria

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5.2.1. Pacific Place Buildings, Hong Kong

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3.2.1.Fuenlabrada Shopping Center, Spain

35 000 m2

Construction time ≈ 3 months(3 000 m2 / week)

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3.55

32

3.90

1.55 1.55 8.15 1.55 1.55 8.775 1.55 1.55

50

70

35 4.00

50

2.50

50

2.50 2.50

50

5.25

50

2.50 2.50

50

6.375

50

2.00 2.00

50

3.51

30

60

65

55

30

-3,92

63

63

63

63

1.00

30

16.70

-0,05

3.587

+4,15

55

55

+8,35

4.55

3.90

30

3.50

30+12,15

Section

10.00 11.25 11.87 5 10.00

+18,00

A B C D E

1 2 3 4 5 6

E

C

B

A

6.095 6.095 8.125 11.875 4.055

10.0

011

.25

11.8

7510

.00

D

4.2.1.Foundation raft “P&C Bergisch Gladbach”, Switzerland

City centre area

Original solution - pile-raft foundation

Alternative solution – banded postensioned foundation raft

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8 9 10 11 12

E

3.2.4.1Crown Plaza Hotel,Funchal

Solid slab, t = 0.25m, spans ≈ 7.5m

“Local” use of post-tensioning in areas where greater spans (10m to 12m) are needed.

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1

A B

2

e=0.16

C

A

D E F

A

6.99

e=0.40

6.88 6.18 6.99 2.58

2.53

3.23

2.68

1.91

e=0.16

e=0.16

e=0.16

e=0.40

e=0.16

e=0.12

e=0.16

e=0.12

4.00

3.30

2.87

67

SECTION A-A

6'

1.62 0.53

2.24

4.75

45

1.00

3

3.05

0.16

0.25

0.22

2.22

1.36 0.12

fp0.1k > 1670 MPafpuk > 1860 MPa

Ordinary Steel: S400

3.23

2 1

0.160.

40

Prestressing Steel

CORBEL GEOMETRY0.12

Concrete: C30

0.40 0.16

PLAN

3.2.4.2“Oeiras House”, LisbonPROBLEM STATEMENT/QUESTION

At the South enter, the corbel have no continuity with the interior slab.

A solid band, free spanning about 13m, has to equilibrate vertical and bending effects induced by the corbel

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DETAIL 1

B

F

DETAIL 1

F

A

C, D & E

CABLE A

CABLES C, D & E

CD

EF

BA B

CABLE LAYOUT

DE

C

F

B

F

SECTION A-A (Cables A, C, D and E)

PLAN

B A

CABLES A, B, C, D, E, F - 3 Monostrands (0.6'') - Peff=3x150 kN

1

2

13.06

0.05

0.05

A B DC E

B D

A

fp0.1k > 1670 MPafpuk > 1860 MPa

Ordinary Steel: S400

Prestressing Steel

Concrete: C30

BF

C

A

DE

VIEW

SECTION

3 MonostrandsPeff = 150 kN/strand)

Peff = 150 kN/strand)3 Monostrands

ADOPTED SOLUTION

Prestressing lay-out to balance bending and torsion effects

Design Criteriom – to balance permanent deflections

Unbonded monostrands

3.2.4.2“Oeiras House”, Lisbon

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-55-50-45-40-35-30-25-20-15-10-505

d [m

m] g

g+P

RESULT

3.2.4.2“Oeiras House”, Lisbon

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K J H Ea

5.375 4.85 4.525

Section with tendon

6.2.2.Platform for a Heliport “KHIB-Ibbenburen”Switzerland

About 20 m above ground level

Extending 5 m over the outside edge of the existing building

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Post-tensioning principles and technology can be used in any structure, independently of its importance, covering a wide range of building structural applications, improving the construction quality and promoting concrete as structural material.

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Bullet31 TAW Budapest 05 - FenixEdu · e=0.12 e=0.16 e=0.12 4.00 3.30 2.87 7 6 SECTION A-A 6' 1.62 0.53 2.24 4.75 5 4 1.00 3 3.05 0.16 0.25 0.22 2. 1.36 0. 1 2 fp0.1k > 1670 MPa fpuk

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