A Presentation on Petronas  Twin Towers, Kuala Lumpur, Malaysia

By- Nawal Kishor Dwivedi

General Facts

  • 6rd tallest building in the world as on March 2014
    6rd tallest building in the world

    6rd tallest building in the world

  • Tallest building in world from 1998 to 2004
  • Preceded by International Commerce Center, Hong Kong ,China
  • Surpassed by Nanjing Greenland Financial Complex ,China
  • Location : KLLC , Jalan Ampang of Kuala Lumpur, Malaysia
  • Type : Commercial , Tourist attraction
  • Construction was started on 1st march 1993 & completed on 1st march 1996
  • Cost : us$ 1.6 billion
  • Owner : KLLC holdings
  • Number of storey: 88 (+ 4 basement floors)
  • Total height : 451.9 m (architectural )  378.6 m ( roof )
  • LIFTS/ELEVATORS : 78
  • Floor Area : 395000 M Sq
  • Material : Concrete , Steel
  • Architect : Cesar Pelli
  • Structural Engineer : Thornton Thormaseti
  • Contractors : Tower 1 : Hazama Corporation   Tower 2 : Samsung Engg.& Co.

Project Data

  • Each tower : 88 storeys
  • Tower 1 : Petronas head quarters
  • Tower 2  : Local and international private, Tenants, Klcc holdings
  • Smaller circular bustle  or annex added to each tower rising 44 storey
  • Towers connected by sky bridge at 41st & 42nd storey
  • Sky bridge: centre-line span: 58.44 metres; width, 5.29 metres ,Height, 9.45 metres
  • Finished ceiling height: 2.65 metres
  • Height of pinnacles: 73.5 – 75 metres
  • Floor area varries as tower accends
  • CENTRAL CORE GROSS AREA :510 m sq approx
  • Facilities : 3 level concert hall,   6 storey retail and entertainment park,  Petroleum research centre,  4 STOREY BASEMENT PARKING etc.

Foundation

  • Early excavation problem : limestone bedrock
  • 300000 metric ton weight of each tower to be spread on mat foundation
  • Pressure exerted by each tower : 1140 k-pa (more than twice bearing cap. Of soil available) Also bed rock was sloping – may lead to failure
    Petronas Twin Towers foundation section

    Petronas Twin Towers foundation section

  • Construction site shifted 60 m away, Finally rested on concrete mat anchored with concrete friction piles
  • 4.5 m thick raft supported on 45-105 m rectangular piles
  •  Longer piles where deep bed rock- to avoid differential settlement
  •  M45 concrete used for piles, 13200 cu m of m60 concrete used in raft
  •  Chilled water used- minimize differential temperaure

Central Core

  • Central core in each tower, accommodate – lifts, exit stairs, mechanical services
  • Two solid walls running n-s and e-w- web cantilever beams projecting-makes it stiff takes more than half the twisting moment
  • Highly reinforced thick corner walls-  resist wind
  • Core varries from 22 sq m to 19 x 22 m in four steps
  • Outer walls 750 to 350 mm
  • Inner walls costant 350 mm- to avoid complication with lift shaft  concrete grade drops from 80 -40 mpa as it accents
Central core and Floor Plan

Central core and Floor Plan

Columns

  • Columns cast in reusable steel forms
  • Finely finished columns open to view at most of the floors
  • 16 tower column- vary along hight in dia. 2.4 m to 1.4 m dia
  • Concrete varied from M80 to M30 in 3 steps, 12 bustle columns – 1.4m to 1m
  • Setbacks at 60, 73 and 82, Sloping columns over 3 story heights
  • Above floor 84 – high slope – steel column used to avoid complication

 

Beams

  • Tapered ring beams all around
  • Depth 1.15 m AT COLUMN TO 725 mm AT FLAT ZONE
  • Span variation due to column changes and set backs
  • Beam grade matches column grade to simplify pumping

Outriggers

  • E-w outrigger link core and columns at floor 38-40
  • 3 level beams linked by mid span posts – help resist wind effect

Sky Bridge

  •  Double deck bridge spanning 58.4 m
    Petronas Twin Towers Sky Bridge

    Petronas Twin Towers Sky Bridge

  •  Connects two tower at skylobby elevator transfer station on floor 41 and 42
  •  Easy circulation b/w upper tower floors
  •  Minimize lift usage
  •  Reduces fire exit requirement
  •  Great height and span requires steel for light weight and easy const.
  •  Two hinged arch supports the span Self centering action from restrain at arch crown and spherical pin at supports

Pinnacle

  •  Each tower crowned by- 73 m tapering top
  •  Accommodates – building maintenance machine , aviation lighting and lighting protection
  •  Due to steep sloping column
  •  Concrete construction impractical
  •  Steel used throughout
  •  Lower pinnacle- 8 structural steel frames
  •  Upper pinnacle – single mast of tapering circular cross section

Dynamic Studies

Cross wind effects  on structure and user comfort,

Pinnacle elevation

Pinnacle elevation

Analytical modelling :

  •  3d modelling using sap90  including perimeter beams, columns, central column representing core & outrigger system
  •  column gross cross section properties used- compressive stresses dominant
  •  Elastic moduli ‘e’ values varied with strength  according to aci318
  •  ‘E’ values not reduced for creep- short term wind loading
  •  Beams assumed to be ‘cracked’- avg. Stiffness i/2

Wind modelling

  •   Design wind 35 m/s assumed at 10m elevation
  •   Return period 50 years
  •   Forcing function determined using it
  •   Analysis for dynamic force at 1-2% damping
  •   Results revealed
  •   2% damping reduces base shear
  •   Values well below limits
  •   No  reqirement of tuned dampers

Similar dynamic modelling done for sky bridge,pinnacle,  Sky bridge reqired tuned mass dampers-3 each leg

Conclusion

  •  Mixed construction for cost and usability benefit
  •  Use of HPC – reasonable sections, low cost ,  more space
  •  Concrete construction- simple equipment’s less skill , easy connection
  •  Concrete – benefits wind behavior –inherent stiffness and damping
  •  Steel – fast and flexible erection- permits last minute change
  •  Wind excitation –beneficial for–size 55mm to .3m
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •