High rise

1. HIGHRISE
STRUCTURES- I
Lecture 8
Dr Anjali S Patil

2. 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 settings
◻ cultural significance and prestige
◻ human aspiration to build higher

3. High rise is defined differently by different bodies
Emporis standards-
“A multi-story structure between 35-100 meters tall, or a building of
unknown height from 12-39 floors is termed as high rise.
Massachusetts, United States General Laws – A high-rise is being
higher than 70 feet (21 m).
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.

4. Timeline of high rise structures

5. STRUCTURE SYSTEMS
• Bearing wall structures (upto approximately 28 stories)
• Core structures (and bridge structures)
• Suspension buildings
• Skeleton structures and flat slab building structures
• Rigid frame (upto 30 stories)
• Braced frame structures : frame with shear wall/ core (45 stories)
• Braced frame structures : frame with shear wall/ core (45 stories)
• Staggered wall- beam structures (upto 40 stories)
• Frame with shear, band and outrigger trusses (upto 60 stories)
• Partial tubular frames (upto 65 stories)
• Exterior framed tubular (upto 90 stories)
• bundled framed tubes (upto 110 stories)
• Exterior diagonalised tubes (upto 115 stories)
• Mega structures
• Hybrid structures

6. DEVELOPMENT OF STRUCTURAL SYSTEM M
S
First Generation1780-1850
⮚ 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.
HOME INSURANCE
BUILDING
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 skeleton of welded- or riveted-steel
columns and beams, often encased in concrete, runs through
the entire building.
⮚ This type of construction makes for an extremely strong
structure, but not such attractive floor space. The interiors are
full of heavy, load-bearing columns and walls
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
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.
Burj Khalifa, in Dubai

8. Structural system classification

9. TALL BUILDING TRENDS IN 2013
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.)

10. TALL BUILDING TRENDS IN 2013
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

11. 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.
◻ Gravity loads are caused by dead and live loads. Lateral loads tend to snap
the building or topple it. The building must therefore have adequate shear
and bending resistance and must not lose its vertical load-carrying capability.
The skyscraper pushes down on into the ground
.But when the wind blows, the columns in the
windy side stretch apart, and the columns on the
other side squeeze together.

12. Variation of wind load with the variation of forms
Round shape
Minimum wind pressure
Irregular shape
Maximum wind
pressure
Plan view

13. LOAD DISTRIBUTION SYSTEM :
All type of loads can be considered
as_
• Vertical load &
• Lateral load
Vertical loads transfer through_
• Bearing wall
• Column
• Column
• Core
• Diagonal frame
Lateral loads transfer through_
• Shear wall
• Slab
• Beam
• Diagonal Frame

14. Structural member:
Beam :
Beam is a rigid structural member designed to carry
and transfer loads across spaces to supporting
elements.
Column :
A rigid relativity slender structural member designed
primarily to support axial compressive loads
applied at the member ends.
In high rise buildings it can be use as mega column,
In high rise buildings it can be use as mega column,
concrete filled tubular(CFT) etc.
Shear wall:
A vertical diaphragm or wall acting as a thin, deep
cantilever beam in loads to the ground foundation.
Bracing :
It is a structural element for positioning,
supporting, strengthening or restraining the
member of a structural frame.

15. Core :
Core is one of the most important structural and
functional elements of the high rise building.
The core of a building is the area reserved for elevators’ stairs,
mechanical equipments and the vertical shafts that are
necessary for ducts, pipes and wires.
Its wall are also the most common location for the vertical
wind bracing.
The placement of the service core stems from four generic types
which are :
which are :
- Central core
- Split core
- End core
- Atrium core
Central core End core Atrium core
split core

16. Type I : Shear Frames
Type II : Interacting Systems
Type III: Partial Tubular
Systems Type IV: Tubular
Systems
(CTBUH, 1980)
Structural typology:
According to ‘Council on Tall Buildings and Urban habitat’ there are four
types
of structural system-
According to Mir M. Ali and Kyoung Sun Moon, Structural systems of tall
buildings can be divided into two broad categories-
1.interior structures and
2.exterior structures.
According to material it can be also-
1. Concrete type and
2. steel type

17. INTERIOR STRUCTURES
By clustering steel 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
Interior structure
1. Rigid Frames
2. Shear Wall Hinged Frames
3.Shear Wall (or Shear Truss) - Frame Interaction System
4. Outrigger Structures
Interior and exterior classification is based on the distribution of the components of the
primary lateral load-resisting system over the building.
4. Outrigger Structures
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.
Exterior structure
1. Tube
2. Diagrid
3. Space Truss Structures
4. Super frames
5. Exo-skeleton

18. INTERIOR STRUCTURES
By clustering steel 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.

20. 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.
◻ Consist of columns and girders joined by moment
Seagram
building
◻ Consist of columns and girders joined by moment
resistant connections.
◻ Can build upto 20 to 25 floors
2)SHEAR WALL STRUCTURE
◻ Concrete or masonry 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

21. 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
◻
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.
◻ An build upto 150 floors
Shangai World
financial centre

22. 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 incarnation of the tube, the
perimeter of the exterior consists of
closely spaced columns that are tied
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

23. 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 pluralistic styles.
◻ Early designs of tall buildings recognized the
effectiveness of diagonal bracing members in
◻
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

24. 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.
◻
Bank of China, Hong Kon
◻ 4)Exo skeleton structure
◻ In exoskeleton 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.
Hotel de las Atres

25. 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
◻ 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.

26. 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
◻ 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.

27. References :
• Council on Tall Buildings and Urban Habitat. (CTBUH)
• Structural Developments in Tall Buildings: Current Trends and Future
Prospects -Mir M. Ali† and Kyoung Sun Moon
• http://www.aij.or.jp/jpn/symposium/2006/loads/Chapter7_com.pdf
• High-rise building structure -Wolfgang Schueller
www.greatbuilding.com .
• www.greatbuilding.com .
• www.riba.com .