2015-10-08

Bella Hotel Bella Hotel

Image size: 7,94 cm x 25,4 cm

Bella Sky •Taking precast concrete to the limit

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Kaare K.B. Dahl

2015-10-08

Bella Hotel

Agenda

• The background

• Key figures

• Handling the vertical load

• Horizontal stability

• Steel or concrete?

• 3 of the greatest challenges

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Project team

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Owner: Bella Conference Center

Architect: 3xN

Structures: Ramboll

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Bella Conference Center

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Bella Hotel

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Basic requirements • 4-star hotel • >800 rooms • Max. height 78.235m above sea level • Direct acces to the Bella Center • Northern road uninterrupted

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Key figures

• two 76.5 m high towers

• 24 stories

• 2 connecting bridges

• 812 4-star hotel rooms

• 44.000 m2

• 3 restaurants

• 32 meeting rooms

• 800.000.000 BRL

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A leaning building

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Pisa: 4 degrees

Bella Hotel: 15 degrees

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Tower 1 Horizontal displacement of the top 10 stories

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Tower 2 Horizontal displacement of the lower 14 stories

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Main forces

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Destabilizing moment

1.200.000 kNm

Max. foundation load

300.000 kN acting on

15*20m slab

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Basic buildup

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Precast elements

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Why do the towers lean?

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6.616 concrete elements

• walls

• columns

• beams

• hollow core slabs

450 staircase concrete elements

The main structural system (as we thought it was going to be at the very start)

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The main structural system as it really is

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Leading horizontal loads towards the back

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Normal floor plan

6. floor

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Calculations

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Horizontal and vertical load take-down The whole structure is calculated in one go

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Structural calculations using ROBOT:

13 load cases

6-9 iterations pr. loadcase

Computertime per tower: 3 PC’s each 48 hours

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Iterations – correct modelling of foundations

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Starting point

Iteration: 1

Iteration: 2

Iteration: 3

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Horizontal stability

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Basic buildup

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Longditudinal stability Tower 1

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Bella Hotel 30

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Longditudinal stability Tower 1

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Longditudinal stability Tower 1

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Transverse stabilitet

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Steel or Concrete?

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Why precast concrete instead of steel frame?

• Stiffness • A steel frame structure will require many diagonals.. • low selfweight=> vibrationproblems.

• Sound transmission • very demanding transmission values between rooms is readily solved by using concrete walls.

• Firesafety • Steel requires fireproofing – concrete does not.

• Quick erection of main structural system • there is – after all – only a few leaning elements.

• Overall shorter time for building the house • there are many walls in this building.

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Bella Hotel

Steel or concrete?

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Bella Hotel

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Why precast concrete instead of steel frame?

• Stiffness • A steel frame structure will require many diagonals.. • low selfweight=> vibrationproblems.

• Sound transmission • very demanding transmission values between rooms is readily solved by using concrete walls.

• Firesafety • Steel requires fireproofing – concrete does not.

• Quick erection of main structural system • there is – after all – only a few leaning elements.

• Overall shorter time for building the house • there are many walls in this building.

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Vibrations

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Comfort criteria (ISO 10137) residential: max. 0.047 m/s2 office: max. 0.071 m/s2 Calculation max 0.068 m/s2

Comfort criteria residential: max. 0.04 m/s2 office: max. 0.06 m/s2 Calculation max 0.042 m/s2

0.68 Hz 1.07 Hz

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Why precast concrete instead of steel frame?

• Stiffness • A steel frame structure will require many diagonals.. • low selfweight=> vibrationproblems.

• Sound transmission • very demanding transmission values between rooms is readily solved by using concrete walls.

• Firesafety • Steel requires fireproofing – concrete does not.

• Quick erection of main structural system • there is – after all – only a few leaning elements.

• Overall shorter time for building the house • there are many walls in this building.

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General build-up

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≥ ≥

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Why precast concrete instead of steel frame?

• Stiffness • A steel frame structure will require many diagonals.. • low selfweight=> vibrationproblems.

• Sound transmission • very demanding transmission values between rooms is readily solved by using concrete walls.

• Firesafety • Steel requires fireproofing – concrete does not.

• Quick erection of main structural system • there is – after all – only a few leaning elements.

• Overall shorter time for building the house • there are many walls in this building.

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General build-up

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≥ ≥

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3 of the greatest challenges

• The connection between the longitudinal and transvers wall

• Vertical joints in walls (shear capacity)

• The top connecting bridge

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Transvers wall

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Joint over transvers wall elements

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Transvers wall elements

Beam element (transvers vall)

Insitu joint (transvers wall) Longitudinal wall

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Joint over transverse wall elements

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320mm

500mm 700mm

23 stories 24 stories

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Joint over transvers wall elements

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Transvers wall elements

Beam element (transvers vall)

Insitu joint (transvers wall) Longitudinal wall

8Y25 in top and bottom

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Longitudinal wall

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Joint over longitudinal wall

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Longitudinal wall element

Insitu-joint (longitudinal wall)

Beam element (transvers wall)

4Y32 in top and bottom

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The connection between the longitudinal and transversal wall

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Joint over longitudinal wall

Joint over transvers wall

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4 Y32 + 6 Y25 + 2 Y16

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Vertical joints in walls we need from 50 to 550kN/m

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50kN/m

550kN/m

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The top connecting bridge

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Connecting bridge

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Factors influencing the movements of the towers

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• Windload

• Wind on the facades

• Torsion of the towers

• Oscillation

• Eccentric liveload (long.)

• Eccentric liveload (transv.)

• Creep of the concrete

• Creep of the subsoil..

• ”Skewed” heating

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Tilnærmet flytning i bagenden er 12mm Settlement of heel

approx. 12mm

Settlement of toe approx. 22mm

Creep of subsoil PLAXIS-3D-calculations

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Factors influencing the movements of the towers

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• Windload

• Wind on the facades

• Torsion of the towers

• Oscillation

• Eccentric liveload (long.)

• Eccentric liveload (transv.)

• Creep of the concrete

• Creep of the subsoil

• ”Skewed” heating

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y

x

Resulting movement

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Ux Uy Partial Uxregn Uyregn

(mm) (mm

)

(mm) (mm)

Creep 140 18 1,00 140 18

Wind 7 71 1,00 7 71

Eccentric 16 60 1,00 16 60

Thermal 12 98 0,5/1,3 5 38

Total away 168 186

Total against 28 169

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Thank you

Questions?