Structural systems in high-rise buildings have evolved over three generations from the late 18th century to present. Early systems used stone, brick, cast iron and wood. Later systems in the 1850-1940 period used steel frames with concrete. Modern systems from 1940 on use steel cores, outriggers, tube designs, diagrids, and superframes to resist gravity and lateral wind loads. Definitions of high-rise vary but are generally above 35 meters. Drivers for tall buildings include land scarcity, demand for space, and prestige. Innovators like Fazlur Rahman Khan pioneered new efficient systems. Future trends may include taller megatalls over 600 meters using new composite systems and materials.

1. STRUCTURAL SYSTEMS IN
HIGH-RISE BUILDINGS

2. INTRODUCTION
It is difficult to distinguish the characteristics of a
building which categorize it as tall/ High Rise.
In a typical single-storey area, a five story building
will appear tall.
In large cities, a structure must pierce the sky
around 70 to 100 stories if it is to appear tall in
comparison with its immediate neighbors.

3. INTRODUCTION AND DEFINITION
High rise is defined differently by different bodies
 Emporis standards-
 “Amulti-story structure between 35-100 meters tall, or a building of unknown
height from 12-39 floors is termed as high rise.
The International Conference on Fire Safety –
"any structure where the height can have a serious impact on evacuation“
Massachusetts, United States General Laws –
A high-rise is being higher than 70 feet (21 m).
Buildings higher than 100m is termed as skyscraper according to emporis.
Buildings 300m or higher is termed as super tall and buildings 600m or taller is
termed as mega-tall.
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In this study we shall consider all buildings above 35 meters (115 feet)

4. DEMAND FOR HIGH-RISE BUILDINGS
High rise buildings are becoming more prominent these
days due to following reasons
 Scarcity of land
 Increasing demand for business and residential space
 Economic growth
 Technological advancement
 Innovations in structural systems
 Desire for aesthetics in urban cities
 Cultural significance and prestige
 Human aspiration to build higher

5. Dr. Fazlur Rahman Khan (Structural Engineer)
He has been called the “Einstein of
structural engineering" and the "Greatest
Structural Engineer of the 20th Century" for
his innovative use of structural systems
that remain fundamental to modern
skyscraper design and construction.
Innovations: Tube structural systems, Framed tube, Trussed
tube and X-bracing, Bundle tube, Tube in tube, Outrigger and
belt truss, Concrete tube structures & Shear wall frame
interaction system

6. DEVELOPMENT OF STRUCTURAL SYSTEM MS
 First Generation 1780-1850
 The exterior walls of these buildings consisted of
stone or brick, although sometimes cast iron was
added for decorative purposes.
 The columns were constructed of cast iron, often
unprotected; steel and wrought iron was used for
the beams; and the floors were made of wood.
 Second Generation 1850-1940
 The second generation of tall buildings, which
includes the Metropolitan Life Building (1909), the
Woolworth Building (1913), and the Empire State
Building (1931), are frame structures, in which a
HOME
INSURANCE
BUILDING
skeleton of welded- or riveted-steel columns and
beams, often encased in concrete, runs through
the entire building.
EMPIRE STATE
BUILDING

7. DEVELOPMENT OF STRUCTURAL SYSTEMS
 Third Generation 1940-present
 Buildings constructed from after World War II
until today make up the most recent generation
of high-rise buildings.
 Within this generation there are those of steel-
framed construction (core construction and tube
construction), reinforced concrete construction
(shear wall), and steel-framed reinforced
concrete construction .
 Hybrid systems also evolved during this time.
These systems make use more than one type of
structural system in a building.
Structural system
classification

8. TALL BUILDING TRENDS
Considering the worlds 100 tallest buildings in 1990:
 80 percent were located in North America.
 Almost 90 percent were exclusively office use.
 More than half were constructed of steel.
In 2013, for the world's 100 tallest buildings:
 The largest share (43 percent) are now in Asia. (Only one new 200-m-plus
building was built in North America in 2013, compared to 54 in Asia.)
 Less than 50 percent are exclusively office use. Almost a quarter are mixed-
use and 14 percent are residential.
 Almost half were constructed of reinforced concrete and only 14 percent of
steel. (The remaining are composite or mixed structural materials.)

9. TALL BUILDING TRENDS
A composite tall building
utilizes a combination of both
steel and concrete acting
compositely in the main
structural elements.
A mixed—structure tall
building is any building that
utilizes distinct steel or
concrete systems above or
below each other.
Structural material
usage from 1930
to 2013

10. STRUCTURAL CONCERNS
 The primary structural skeleton of a tall building can
be visualized as a vertical cantilever beam with its base
fixed in the ground. The structure has to carry the vertical
gravity loads and the lateral wind and earthquake loads.
The skyscraper pushes down on into the ground.
But when the wind blows, the columns in the windy
side stretch apart (Tension), and the columns on the
other side squeeze together (Compression).

11. STRUCTURAL CONCERNS
Fighting gravity
The weight of the building is supported by a
group of vertical coloumns
Each floor is supported by horizontal steel/concrete
girders running between vertical columns.
Curtain wall made of steel and concrete
attaches to the outside
Wind resistance
Buildings taller than 10 storeys would generally require additional
steel for lateral system.

12. STRUCTURAL CONCERNS
 For taller skyscrapers, engineers have to construct especially
strong cores through the center of the building for the wind
resistance.
 The effects of wind can also be minimized by aerodynamic shaping
of the building. Wind tunnel testing considers appropriate loading for
overall lateral system design and cladding design, and predicts
motion perception and pedestrian level effects.
 Use of damping systems
as the building becomes taller
and the building’s sway due to
lateral forces becomes critical,
there is a greater demand on the
girders and columns that make
up the rigid-frame system to
carry lateral forces.

13. CLASSIFICATION OF TALL BUILDING
STRUCTURAL SYSTEMS
Can be classified based on the structural material used such as concrete or steel
Structural systems of tall buildings can also be divided into two broad categories:
 1) INTERIOR STRUCTURES
 2) EXTERIOR STRUCURES
 This classification is based on the distribution of the components of the primary lateral
load-resisting system over the building.
 A system is categorized as an interior structure when the major part of the lateral
load resisting system is located within the interior of the building.
 Likewise, if the major part of the lateral load-resisting system is located at the building
perimeter, a system is categorized as an exterior structure.
It should be noted, however, that any interior structure is likely to have some minor
components of the lateral load-resisting system at the building perimeter, and any
exterior structure may have some minor components within the interior of the building.

14. INTERIOR STRUCTURES
By clustering steel/concrete columns and beams in
the core, engineers create a stiff backbone that can resist
tremendous wind forces. The inner core is used as an
elevator shaft , and the design allows lots of open space on
each floor
EXTERIOR STRUCTURES
In newer skyscrapers, like the Sears Tower in Chicago,
engineers moved the columns and beams from the core
to the perimeter, creating a hollow, rigid tube as strong as
the core design, but weighing much, much less.

15. Seagram
building
INTERIOR STRUCTURAL SYSTEM
 1)RIGID FRAME
 A rigid frame in structural engineering is the load-
resisting skeleton constructed with straight or curved
members interconnected by mostly rigid connections
which resist movements induced at the joints of
members. Its members can take bending moment,
shear, and axial loads.
 Can build upto 20 to 25 floors
 2)SHEAR WALL STRUCTURE
 Concrete continuous vertical walls may serve both
architecturally partitions and structurally to carry
gravity and lateral loading. Very high in plane
stiffness and strength make them ideally suited for
bracing tall building
 Usually built as the core of the building
 Can build upto 35 Floors
Shear wall core

16. 3) OUTRIGGER STRUCTURES
 The core may be centrally located with
outriggers extending on both sides or in some
cases it may be located on one side of the
building with outriggers extending to the
building columns on the other side
 The outriggers are generally in the form of
trusses (1 or 2 story deep) in steel structures,
or walls in concrete structures, that effectively
act as stiff headers inducing a tension-
compression couple in the outer columns.
 Belt trusses are often provided to distribute
these tensile and compressive forces to a
large number of exterior frame columns.
 Build upto 150 floors
Shangai World
financial centre
Plan View

18. EXTERIOR STRUCTURES
 1) Tube system
 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 of the tube, the perimeter of the
exterior consists of closely spaced columns that
are tied together with deep spandrel 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.
 The different tubular systems are-
1)Framed tube 2)Braced tube
3)Bundled tube 4)Tube in tube

19. 2) Diagrid systems
 With their structural efficiency as a varied version of
the tubular systems, diagrid structures have been
emerging as a new aesthetic trend for tall buildings in
this era of mixture of different styles.
 Early designs of tall buildings recognized the
effectiveness of diagonal bracing members in
resisting lateral forces.
 Most of the structural systems deployed for early tall
buildings were steel frames with diagonal bracings of
various configurations such as X, K, and chevron.
However, while the structural importance of diagonals
was well recognized, the aesthetic potential of them
was not appreciated since they were considered
obstructive for viewing the outdoors.
 Efficiently resists lateral shear by axial forces in the
diagonal members but have Complicated joints
Hearst tower , New York

20. 3) Space truss
 Space truss structures are modified braced tubes with
diagonals connecting the exterior to interior. In a typical
braced tube structure, all the diagonals, which connect the
chord members – vertical corner columns in general, are
located on the plane parallel to the facades.
 However, in space trusses, some diagonals penetrate the
interior of the building.
4) Exo skeleton structure
 In exo-skeleton structures, lateral load-resisting systems
are placed outside the building lines away from their
facades.
 Due to the system’s compositional characteristics, it acts
as a primary building identifier – one of the major roles of
building facades in general cases.
 Fire proofing of the system is not a serious issue due to
its location outside the building line.
Bank of China,
Hong Kon
Hotel de las Atres

21. 5) Super frame structures
 Superframe structures can create ultra
high-rise buildings upto 160 floors.
 Superframes or Megaframes assume
the form of a portal which is provided
on the exterior of a building.
 The frames resist all wind forces as
an exterior tubular structure. The
portal frame of the Superframe is
composed of vertical legs in each
corner of the building which are linked
by horizontal elements at about every
12 to 14 floors.
 Since the vertical elements are
concentrated in the corner areas of
the building, maximum efficiency is
obtained for resisting wind forces.

22. Case Study : PETRONAS TOWER
Petronas tower is a symbol of national pride and shows the
nation's advancement in the word economy and technologies.
Conrete was used for its construction mainly because it
was easily available and cheap when compared with steel,
which was a new material for the builders.
The architect successfully incorporated malaysian and
Islamic motiffs in the design. The skybridge was an important
feature of the design which was implemented later. Petronas
tower has 'tube in tube' structural system. The structural
members are made with high strength concrete which was
cast in site. The perimeter columns are held together with the
help of ring beams. The internal core structure is made of
concrete shear walls. The building didn't require extra
damping systems because the heavy structural members made
of concrete. Even though no new advncements in technology
was made during the project , the available technology was used
smartly.

24. BURJ KHALIFA DUBAI, UAE
 The Burj Dubai project is designed to be the centerpiece of
the large scale Burj Dubai Development that rises into the
sky to an unprecedented height of 800 meters and that
consists of more than 160 floors.
 The decision to build Burj Khalifa is reportedly based on the
government's decision to diversify from an oil based
economy to one that is service and tourism based.Unlike
many super-highrise buildings with deep floor plates,
 the Y-shape floor plans of Burj Dubai maximize views and
provide tenants with plenty of natural light.
 According to officials, it is necessary for projects like Burj
Khalifa to be built in the city to garner more international
recognition, and hence investment. The structural system of
burj khakifa was a new system developed for the building.
The system is called 'butressed core' . In this system the
lateral loads and gravity loads are shared equally between
the interior core and perimeter structural systems linked by
the link beam which makes the structure super strong.

25. BURJ KHALIFA
DUBAI, UAE
The image shows the structural
systems employed in the building,
the blue members are the load
carrying concrete wall system, all
the wall structures are linked to the
core with the help of link beam.

26. FUTURE TALL BUILDINGS
 Nothing could be more stunning than the latest generation of skyscrapers, known as the 'supertalls'.A tower has
to be over 300 metres high to qualify as a supertall, but there is no shortage of contenders: at 829.8 metres high,
the Burj Khalifa in Dubai is undeniably the world’s tallest building, but it won’t be for very long as the race to build
upwards continues around the world.
 We are entering the era of the “megatall.” This term is now officially being used by the Council to describe
buildings over 600 meters in height, or double the height of a supertall .

27. CONCLUSION
 With the present technology and known materials , it is possible to
build more higher and faster.
 It is now possible to build skyscrapers so fast using pre- fabricated
units that it can lead to environmental problems, stress on
resources and overcrowding if not controlled.
 To build higher the base of the building will have to be made wider.
The bundled tube system was a great innovation and was able to
span great heights during it's time , to attain the height of burj
khalifa the bundled tube system will need a bigger base when
compared with the buttressed core system.
 New improved structural systems and new materials in the future
can lead us to even greater heights and more stable buildings. It’s
not technology holding buildings back. It’s money.

28. THANK YOU