1.
Today is My Presentation Topic Name Is –
Explain any tube system and structural
configuration of a building having that system.
Mohammad Khasrul Alam.
ID No. : 003-18-23.
Department Of Civil Engineering.
Southern University Bangladesh.

2.
Index
CONTENT
ITRODUCTION
CONCEPT OF TUBE STRUCTURE
CONCEPT
HISTORY
TYPES
COMPARISON

3.
INTRODUCTION -
 The tube is the name given to the systems where in order to
resist lateral loads (wind, seismic, etc.) a building is designed to
act like a three-dimensional hollow tube. The system was
introduced by Fazlur Rahman Khan while at Skidmore, Owings
and Merrill's (SOM) Chicago office. The first example of the
tube’s use is the 43-story Khan-designed DeWitt-Chestnut
Apartment Building in Chicago, Illinois, completed in 1963.
 The system can be constructed using steel, concrete, or
composite construction (the discrete use of both steel and
concrete). It can be used for office, apartment and mixed-use
buildings. Most buildings in excess of 40 stories constructed in
the United States since the 1960s are of this structural type.

4.
Concept of tube structure
 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.
CONCEPT
 The tube system concept is based on the idea that 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 that amounts to a dense and strong
structural wall along the exterior of the building.
 This exterior framing is designed sufficiently strong to resist all
lateral loads on the building, thereby allowing the 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 gravity loads within the
structure to it and increases its ability to resist overturning due to
lateral loads.

6.
HISTORY
 Since 1963, a new structural system of framed tubes appeared in
skyscraper design and construction.
 Fazlur Khan defined the framed tube structure as "a three dimensional
space structure composed of three, four, or possibly more frames, braced
frames, or shear walls, joined at or near their edges to form a vertical
tube-like structural system capable of resisting lateral forces in any
direction by cantilevering from the foundation."Closely spaced
interconnected exterior columns form the tube. Horizontal loads, for
example wind, are supported by the structure as a whole. About half the
exterior surface is available for windows. Framed tubes allow fewer
interior columns, and so create more usable floor space. Where larger
openings like garage doors are required, the tube frame must be
interrupted, with transfer girders used to maintain structural integrity.

7.
Continue…
The first building to apply the tube-frame construction
was the DeWitt- Chestnut apartment building which
Khan designed(1963) and was completed in Chicago by
1965. This laid the foundations for the tube structures of
many other later skyscrapers, including his own John
Hancock Center and Willis Tower, and can been seen in
the construction of the World Trade Center, Petronas
Towers, Jin Mao Building, and most other supertall
skyscrapers since the 1960s. The strong influence of tube
structure design is also evident in the construction of the
current tallest skyscraper, the Burj Khalifa.

8.
See Figure :-
DeWitt-Chestnut apartment
building, Chicago 1965 John Hancock Center 1969

9.
See Figure :-
World Trade Center, 1987 Petronas Towers, 1998

10.
See Figure:-
Jin Mao Tower,
Shanghai,1998
Burj Khalifa, Dubai,2010

11.
TYPES :-
1)Framed tube system
2)Tube -in a tube system
3)Bundled tube system
4)Braced tube system

12.
FRAMED TUBE SYSTEM:-
 This is the simplest incarnation of the tube.
Closely spaced perimeter columns
interconnected by beams. It can take a
variety of floor plan shapes from square and
rectangular, circular. This design was first
used in Chicago's DeWitt-Chestnut
apartment building, designed by Khan and
completed in 1965, but the most notable
examples are the Aon Center and the
destroyed World Trade Center towers.

13.
FRAMED TUBE SYSTEM-
 Closely spaced perimeter columns interconnected
by deep spandrels.
 Whole building works as a huge vertical cantilever
to resist overturning moments.
 Efficient system to provide lateral resistance with
or without interior columns.
 Exterior tube carries all the lateral loading.
 Gravity loading is shared between the tube and the
interior columns or walls, if they exist.

14.
Continue…

15.
Continue…-
 The forces in 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
All 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

16.
TUBE IN A TUBE 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.
 More effective in high-rise structure
because the bending and transverse shears
are supported three-dimensionally at the
flange and web surface in the structure.
 The analysis of tube structures has to be
based on three-dimensional analysis using
finite element.

17.
Continue…
 Proportioning:
 30m minimum floor 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.

18.
Continue…
Behavior of Tube in Tube Tall Building
 (a) Deform shape of frame;
 (b) Deform shape of shear wall;
 (c) Deform shape of composite structure
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

19.
Advantages:
 The wind- resisting system located on the perimeter of
the building – more resistance to overturning
moments.
 Core framing leads to a significant gain in rentable
space.
 Identical framing for all which are no subjected to
varying internal forces due to lateral loads.
 From a practical point of view, the final analysis and
design of the tube can proceed unaffected by the
lengthy process of resolving

20.
BUNDLED TUBE
 Instead of one tube, a building consists of several tubes tied
together to resist the lateral forces. Such buildings have
interior columns along the perimeters of the tubes when
they fall within the building envelope. Notable examples
include Willis Tower and One Magnificent Mile.
 The bundle tube design was not only highly efficient in
economic terms, but it was also "innovative in its potential
for versatile formulation of architectural space. Efficient
towers no longer had to be box-like; the tube-units could
take on various shapes and could be bundled together in
different sorts of groupings." The bundled tube structure
meant that "buildings no longer need be boxlike in
appearance they could become sculpture."

21.
Continue…
 It is a cluster of individual tubes connected together to act
as a single unit
 Maintain a reasonable slenderness (i.e., height-towidth)
ratio – Neither excessively flexible and nor sway too much
 Cross walls or cross frames – increases threedimensional
response of the structure.
 The 110-story Sears Tower completed in 1974 was the first
bundled tube structure in which nine steel framed tubes are
bundled at the base
 Individual tubes could be of different shapes, such as
rectangular, triangular or hexagonal as is demonstrated by
this building.

22.
Diagrammatic view of the bundled tube

23.
BRACED TUBE SYSTEM
 Also known as ‘Trussed Tube’ or ‘Exterior Diagonal-tube
System’ - utilized for greater heights, and allows larger spacing
between the columns
 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.
 The most notable examples are the John Hancock Center, the
 Citigroup Center, and the Bank of China Tower.

24.
Continue…
Behavior under Gravity loading:-
 (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.
Behavior under lateral loading:-
 a) If the diagonals are initially disconnected
from the intermediate columns, the columns
and diagonals of the face will be in tension
while the spandrels are in compression .
 Because of the shear lag effect the
intermediate columns will now be less highly
stressed than the corner columns. the
connection points on the diagonals will be
displaced upward by more than the
corresponding points on the unconnected
intermediate columns.
 b) If the diagonals and intermediate columns
are connected together, iterative vertical
forces will be mobilized
 These upward forces cause an increase in
tension in the intermediate columns

26.
REFERENCES
 Mir M.Ali and Kyoung Sun Moon “Structural
 Developments in Tall Buildings: Current Trends and
 Future Prospects”
 en.wikipedia.org
 Kyoung Sun Moon “Material-Saving Design Strategies
 for Tall Building Structures”
 Text book- Engineering Architecture the vision of Fazlur R. Khan by
 Yasmin Sabina Khan
 sefindia.org

27.
Let's see…

28.
Thank You
See you again any other class and
any other presentation.
End