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Tube structures
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- 2. • What ismean bytube ? • Concept of tubestructure. • Types of tubestructure • Comparison What We Are Going To Learn
- 3. • • • What is meanby tube ? The systems which resist lateral loads on a building is designed to act like a three- dimensional hollow tube. Can be constructed using steel,concrete, or composite construction. It can be used for office,apartment and mixed- use buildings.Mostly buildings with 40+ stories
- 4. • • • Concept of tubestructure A building can be designed to resist lateral loads by designing it as a hollow cantilever perpendicular to the ground. In the simplest incarnation of the tube,the perimeter of the exterior consists of closely spaced columns that are tied together with deep beams through moment connections. This assembly of columns and beams forms a rigid frame.
- 5. • • • • This exterior framingresist alllateral loads on the building, thereby allowingthe interior of the building to be simply framed for gravity loads. Interior columns are comparatively few and located at the core. The distance between the exterior and the core frames is spanned with beams or trusses. This maximizes the effectiveness of the perimeter tube by transferring some of the gravityloads within the structure to it and increases its abilityto resist overturning due to lateral loads.
- 6. Examples of Tubestructures DeWitt-Chestnut apartment building, Chicago 1965 John Hancock Center 1969
- 7. Examples of Tubestructures Jin Mao Tower, Shanghai 1998 Burj Khalifa, Dubai 2010
- 8. • • • • Framed tube system Tube-in a tube system Bundled tube system Braced tube system Types of Tube structures
- 9. Framed tube system Closely spaced perimeter columns interconnected by beams. It can take a variety of floor plan shapes from square and rectangular, circular. Most notable examples are the Aon Center and the destroyedWorldTrade Center towers. • • •
- 10. Framed tube system •Closely spaced perimeter columns interconnected by deep spandrels. • Whole building works as a huge vertical cantilever to resist overturning moments. • Exterior tube carries allthe lateral loading. • Gravity loading is shared between the tube and the interior columns or walls,if they exist.
- 11. • If thetube loaded on sideAB,then the whole frames AB and CD are called ‘Flange frames’ and the frames AD and BC are called ‘Webframe’ Cont… Shear lag
- 12. • The forcesin the web frame are growing smaller toward the center linearly instead in Fig(b) this phenomenon is called Shear lag. • The ratio of the stress at the center column to the stress at the corner column is defined as ‘Shear-lag factor’. • Stress distribution of the flange and web column - opposite sides of the neutral axis are subjected to tensile and compressive forces - under lateral load - Fig. (b) • The prime action is the flexibility of the spandrel beams that produces a shear lag that will increases the stresses in the corner column and reduces those in the inner columns of both the flange panels AB and DC and the web panels AD and BC
- 13. Tube in atube system • An outer framed tube together with an internal elevator and service core. • The outer and inner tubes act jointly in resisting both gravity and lateral loading in steel-framed buildings. • The bending and transverse shears are supported three- dimensionally at the flange and web surface in the structure.
- 14. Proportioning: • 30m minimumfloor dimension • Centrally stability core around lifts/stairs, moment frame around perimeter • 30 to 60 floor, 100 to 160m height • Clear floor plates, but wide perimeter columns and deep perimeter beam constrains view • Traditionally 2 or 3 zone elevator arrangement, but would benefit from optimization using double decks or sky lobbies.
- 15. Behavior ofTube inTubeTall Building • • Respond as a unit to lateral forces The reaction to wind is similar to that of a frame and shear wall structure • The wall deflects in a flexural mode with concavity downwind and maximum slope at the top, while the frame deflect in a shear mode with concavity upwind and maximum slope at the base • Composite structure - flexural profile in the lower part and shear profile in the upper part.The axial forces cause the wall to restrain the frame near the base and the frames to restrain the wall at the top
- 16. • The deflection& wall moment curve indicate the reversal in curvature with a point of inflexion • Fig-c - The shear is uniform over the height of the frame, except near the base where it reduces to a negligible amount • At the top, (where the external shear is zero), the frame is subjected to a significant positive shear - balanced by an equal negative shear at top of the wall, with a corresponding concentrated interaction force acting between the frame and the wall.
- 17. Advantages: Cont… • More resistanceto overturning moments. • Core framing leads to a significant gain in rentable space. • Identical framing for allwhich are no subjected to varying internal forces due to lateral loads. • The final analysis and design of the tube can proceed unaffected by the lengthy process of resolving detail layout and service requirements in the core area.
- 18. Bundled tube • Insteadof one tube, several tubes are tied together to resist the lateral forces. • The bundle tube design wasnot only highly efficient in economic terms, but it was also innovative in its potential for versatile formulation of architectural. • The bundled tube structure meant that "buildings no longer need be boxlike in appearance they could become sculpture."
- 19. • It isa cluster of individual tubes connected together to act as a single unit • Maintain a reasonable slenderness (i.e., height-to- width) ratio – Neither excessively flexible and nor swaytoo much • Cross walls or cross frames – increases three- dimensional response of the structure. • Individual tubes could be of different shapes, such as rectangular, triangular or hexagonal as is demonstrated by this building
- 20. Diagrammatic view ofthe bundled tube
- 21. Braced tube system •Steel buildings-steel diagonals/trusses used • Reinforced concrete buildings-diagonals are created by filling the window openings by reinforced concrete shear walls-diagonal bracing • Braced tube structures are lateral load-resisting systems- Located at the building perimeters made the structural systems for tall buildings much more efficient and economical.
- 22. Behavior under Gravityloading:- • (a) - Intermediate columns will displace downward by more than corresponding points on the diagonal- controlled by the vertical displacement of the less highly stressed corner columns. • (b) - Downward forces on each diagonal are carried at its ends by the corner columns - compressive forces are increased at each intersection with a diagonal = equalization of the stresses in the intermediate and corner columns.
- 25. Types Frame d Tube Material Efficient HeightAdvantages Disadvantages Steel 80 Efficiently resists lateral loads by locating lateral systems at the building perimeter. Shear lag hinders true tubular behavior. Narrow column spacing obstructs the view. Concrete 60 Brace d Tube Steel 100 (With Interior Columns) – 150 (Without Interior Columns) Efficiently resists lateral shear by axial forces in the diagonal members. Wider column spacing possible compared with framed tubes. Reduced shear lag. Bracings obstruct the view. Concrete 100 Comparison of tube systems
- 26. Types Material Efficien t Height AdvantagesDisadvantages Bundl ed Tube Steel 110 Reduced shear lag. Interior planning limitations due to the bundled tube configuration. Concrete 110 Tube in Tube Ext. Framed Tube (Steel or Concrete) + Int. Core Tube (Steel or Concrete) 80 Effectively resists lateral loads by producing interior shear core - exterior framed tube interacting system. Interior planning limitations due to shear core.
- 27. Terima Kasih Hamse AbdiOmar (18660111) Kelas : B Dosen: Pak Agung Sedayu ,M.T