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TRENDS AND INNOVATIONS IN HIGH-RISE BUILDINGS OVER
THE PAST DECADE
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by
1
MASSACM I
OF 1*KCHN0L0LGY
Wenjia Gu
B.S. Civil Engineering
University of Illinois at Urbana-Champaign, 2014
JUL 02 2015
LIBRAR IES
SUBMITTED TO THE DEPARTMENT OF CIVIL AND ENVIRONMENTAL
ENGINEERING IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF MASTER OF ENGINEERING IN CIVIL ENGINEERING
AT THE
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
JUNE 2015
C2015 Wenjia Gu. All rights reserved.
The author hereby grants to MIT permission to reproduce and to distribute
publicly paper and electronic copies of this thesis document
in whole or in part in any medium now known of hereafter created.
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Certified by:
Accepted b v:
Jerome Connor
Professor of Civil and Environmental Engineering
Thesis Supervisor
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?'Hei4 Nepf
Donald and Martha Harleman Professor of Civil and Environmental Engineering
Chair, Departmental Committee for Graduate Students
TT
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TRENDS AND INNOVATIONS IN HIGH-RISE BUILDINGS OVER
THE PAST DECADE
by
Wenjia Gu
Submitted to the Department of Civil and
Environmental Engineering on May 21, 2015 in
Partial Fulfillment of the Degree Requirements for
Master of Engineering in Civil and Environmental Engineering
ABSTRACT
Over the past decade, high-rise buildings in the world are both booming in quantity and
expanding in height. One of the most important reasons driven the achievement is the
continuously evolvement of structural systems. In this paper, previous classifications of
structural systems are summarized and different types of structural systems are introduced.
Besides the structural systems, innovations in other aspects of today's design of high-rise
buildings including damping systems, construction techniques, elevator systems as well as
sustainability are presented and discussed.
To better understand current high-rise buildings, information about buildings above 200
meter completed within recent ten years and the current 100 tallest building in the world is
collected and analyzed. Structural systems of worldwide 100 tallest buildings are discussed,
from which trends are found. Data shows that tubular systems are in vast majority in recent
high-rise building designs and an increasing number of buildings are using concrete and
composite materials instead of steel. Developments in structural systems also reduce
structures' dependence on auxiliary damping devices. Additionally, sustainability has been
given more and more consideration.
Thesis Supervisor: Jerome Connor
Title: Professor of Civil and Environmental Engineering
3
4
TABLE OF CONTENTS
1. IN TRO D U C TIO N .................................................................................
7
2. HIGH-RISE BUILDINGS .........................................................................
9
2.1 D efinition ......................................................................................
3.
9
2 .2 Facts ...........................................................................................
. 10
2 .3 Lo ad s ............................................................................................
. 13
STRUCTURAL SYSTEMS ......................................................................
15
3.1 Previous Classifications ...................................................................
15
3.2 Different Types of Structural Systems ....................................................
18
3.2.1
R igid Fram e ...........................................................................
18
3.2.2
Core and outrigger ................................................................
20
3.2.3
Framed Tube ......................................................................
22
3.2.4
Trussed Tube ......................................................................
23
3.2.5
T ube in tube ...........................................................................
25
3.2.6
Bundled system ......................................................................
26
4. INNOVATIONS IN HIGH-RISE BUILDGINS ............................................
28
4.1 Damping Systems .........................................................................
28
4.2 Construction Techniques .................................................................
30
4.3 E levator System s ..............................................................................
32
5
TABLE OF CONTENTS
4.4 Sustainability .................................................................................
35
5. ANALYSIS OF CURRENT HIGH-RISE BUILDINGS ....................................
37
5.1 Structural System s ...........................................................................
37
5.2 Construction Materials .......................................................................
39
5.3 Sustainability ..............................................................................
40
6. CASE STUDY OF BURJ KHALIFA ...........................................................
42
7. CONCLUSION .................................................................................
47
Al. REFERENCES
....................................................
A2. 100 TALLEST BUILINGS IN THE WORLD BY 2015 ................................
6
48
50
1. INTRODUCTION
Over the past decade, high-rise buildings are both booming in quantity and
expanding in height over the whole world. The number of constructed buildings above 200
meters is increasing every year and the height of the world's tallest building has been raised
from 508 meters in the year 2004 to 828 meters now. Some of the many reasons leading to
this phenomenon include an expanding real estate market that emerges from the steadily
growing global economy, providing investors and contractors with more and more
opportunities, as well as the implicit competitions between countries, metropolitan areas,
and cities to attract more global spotlight.
To fulfill the request of taller and taller buildings, engineers keep working on the
optimization of structural systems to improve the structure's resistance over the load acting
on it. Several studies have discussed the performance of different structural systems from
different perspectives. Over the past decade, a number of high-rise buildings have adopted
integrated structural systems that combined two or more basic structural systems, and
innovative systems such as buttress core system can also be seen in completed buildings.
Besides the aspect of the structural system, structural material also plays an important role in
improving the structural stability and efficiency of the building.
Another important factor that helps pushing the limit of the height of buildings is the
development of construction techniques. With the help of high-tech construction equipment,
concrete can be pumped to a much higher distance than ever, even for high strength concrete.
7
Innovative construction methods also shortened the construction time so that for the owner
the cost of developing a new high-rise building could be reduced.
Other considerations for the design of high-rise buildings including the damping
system, fire design and emergency egress also have some changes over the past decade.
Nonstructural factors such as sustainability of the building are given more and more
importance now.
Information about the 100 tallest completed buildings in the world has been
collected. By studying the structural system as well as other properties of these 100
buildings, the current structural design trends can be found and comparisons between
theoretical analysis and actual can be discussed, which will help engineers break the record
of the most attractive high-rise building.
8
2. HIGH-RISE BUILDINGS
2.1 Definition
Before looking into the design trends and the innovations behind the increasing
number of high-rise buildings over the past decade, it is important to define what high-rise
buildings mean and what makes them different from other structures.
A tall building is referred as a multi-story structure in which most occupants depend
on elevators to reach their destinations. The most prominent tall buildings are called
high-rise buildings in most countries (Challinger, 2008). Although these terms do not have
internationally agreed definitions, a high-rise building, however, can be defined as follows:
According to the Council of Tall Buildings and Urban Habitat, a high-rise building
is "a building whose height creates different conditions in the design, construction, and use
than those that exist in common buildings of a certain region and period".
"Any structure where the height can have a serious impact on evacuation" (The
International Conference on Fire Safety in High-Rise Buildings).
"For most purposes, the cut-off point for high-rise buildings is around seven stories.
Sometimes, seven stories or higher define a high-rise, and sometimes the definition is more
than seven stories. Sometimes, the definition is stated in terms of linear height (feet or
meters) rather than stories. " (Hall, 2007)
Besides what is listed above, another important feature of a high-rise building is that
it is the lateral load not the gravity load that governs the design of the structure. Lateral loads,
9
including wind load and earthquakes, are crucial for high-rise buildings and can be resisted
efficiently by choosing appropriate structural systems. The exact height above which a
building can be defined as a high-rise building is specified by codes of the particular area
where the building is standing.
2.2 Facts
As a representative of the development in high-rise buildings, the record of the tallest
building in the world keeps being broken over the past decade. The 508-meter Taipei 101
Tower (Figure 1) which was opened on the last day of 2014 kept its title as the world's
tallest building for a mere six years before the Bun Khalifa (Figure 2), standing at nearly
830 meters above the ground, stole its glory in the year of 2010. Yet once again, this glory
will be overshadowed in the near future by the 1000-meter-tall Saudi Arabia's new
landmark, the, which is under construction now (Figure 3).
Figure 1: Taipei 101.
10
Figure 2: Bur Khalifa.
Figure 3: Kingdom Tower.
At the same time, the number of high-rise buildings completed is also increasing
each year. Information about buildings that are over 200 meters completed each year from
2005 to 2015 is collected and analyzed. Results show that the number of completed
buildings over 200 meters is basically increasing over time, and the average height of these
buildings is increasing as well. As Figure 4 shows, the number of such buildings completed
in 2014 is three times that in 2005, and the number of buildings above 200 meters is
expected to double by the end of 2015. For the height of completed buildings, as Figure 5
indicates, the average height of all buildings that are above 200 meters completed in the year
-
of 2015 is nearly 50% more than that in the year 2005. It is raised by almost 100 meters
from 213 meters to 303 meters.
200
t84
180
160
140
120
100
807
80
2
.
40
20
: 0
Year of Completion
Figure 4: Number of completed buildings above 200m each year.
11
350
e
300
250
m
200
-150
100
50
0
Year of Completion
Figure 5: Average height of completed buildings above 200m each year.
For the current 100 tallest buildings in the world, as can be seen in Figure 6, there
are only 28 buildings were completed before the year of 2005. As much as 72 buildings
were completed within the past ten years. Researches in this paper are focused on these 72
high-rise buildings.
" Number of buildings
completed between
2005-2015
" Number of buildings
completed before
2005
Figure 6: Completion time of the 100 tallest buildings in the world.
12
2.3 Loads
The structural design of buildings is governed by all the loads that are acting on
them. A standing structure is supposed to experience loads from two aspects - gravity loads
and lateral loads.
Gravity loads are forces acting vertically on the structure such as the self-weight of
the building, so they are the same for high-rise buildings and low-rise buildings unless the
force will be larger at the bottom of high-rise buildings because of the accumulation of loads
over height.
Lateral loads including wind loads and earthquakes, on the other hand, are crucial
for the design of high-rise buildings. Wind loads will increase as the height of the buildings
rises, and they act as pressures on the structure. Therefore, for buildings over certain height,
there will be large lateral loads acting on it due to the wind. Besides the force resulted along
the direction of the wind, dynamic effects of the wind should also be considered. The
structure will also experience motion perpendicular to the direction of the wind, which is
generated by the formation of vortex shedding acting on alternation sides of the structure.
The maximum displacement in the lateral direction generally occurs in the along-wind
direction, while the peak accelerations of the structure occur in the cross-wind direction.
The earthquake is another important factor to consider in the design of high-rise
buildings because of the intense vibration. This will result in the internal forces within the
structure. To reduce the influence of earthquakes on the structure, the structure is supposed
13
to be as ductile as possible to avoid failure, and dampers are usually implemented in the
structure.
14
3. STRUCTURAL SYSTEMS
The maximum height that a building can achieve is dependent on the ability of its
structure to resist loads that are acting on it. The development of the structural system is a
continuously evolving process. Since 1960 before which the predominant type of structural
system was conventional rigid frame, the emergence of tubular systems, core and outrigger
systems has helped to raise the height of buildings. Over the past decade, new developments
in structural systems such as diagrid systems and buttressed core systems have been applied
to the design of many high-rise buildings and showed satisfying performance in the
resistance of gravity and lateral loads.
3.1 Previous Classifications
In 1969, Fazlur Rahman Khan classified structural systems for high-rise buildings
relating to their heights with considerations for efficiency in the form of "Heights for
Structural Systems" diagrams for the first time (Khan, 1969). Later, these diagrams were
upgraded by way of modifications (Khan, 1972, 1973). He developed these schemes for both
steel and concrete buildings as can be seen in Figure 7. Feasible structural systems,
according to him, are rigid frames, shear walls, interactive frame-shear wall combinations,
belt trusses, framed tubes, trussed tubes, tube-in-tube systems and other tubular systems.
15
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Figure 7: Classificationof high-rise building structuralsystems by F.R.Khan
(above: steel; below: concrete).
Another classification of the structural system of high-rise building was developed
in 2007 by Mir M. Ali. This classification is based on lateral load-resisting capabilities. He
divided structural systems of high-rise buildings into two broad categories: interior
structures and exterior structures, which was based on the distribution of the components of
16
ME
the primary lateral load-resisting system over the buildings as shown in Figure 8 (Ali, 2007).
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 loading-resisting systems is located at the perimeter of the buildings, this system
is categorized as an exterior structure.
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Figure 8: Classificationof high-risebuildingstructuralsystems by Mir A. Ali (above: interior
structures; below: exterior structures)
3.2 Different Types of Structural Systems
3.2.1 Rigid Frame
The rigid frame structure, also called moment-resisting frame structure, is the most
basic type of framing systems. It consists of horizontal (girders) and vertical (columns)
members that are connected through rigid connections at the joint (Figure 9). Such framing
systems resist loads primarily through the flexural stiffness of the structural members. The
size of columns is mainly controlled by the gravity load, while the size of girders is
controlled by the requirements of lateral sway of the building as well as the vertical
deflection under dead and live loads. Because of the need for space in high-rise buildings,
the number of columns should be minimized, which increases the span of girders. Therefore,
18
the size of girders will be increased to ensure the stability of the structure. Additionally, as
the height of buildings increases, bending rigidity of both girders and columns should be
increased to reduce the lateral deflection. Besides, the expense of the moment-resisting
connections is really high. Therefore, the rigid frame would be an efficient structural system
for buildings under 30 stories (Kowalczyk, Sinn, & Kilmister, 1995).
Connections must be
capable of resisting
bending moments
Deformed shape
Bending moment diagram
Figure 9: Rigidframe.
19
3.2.2 Core and Outrigger
The core and outrigger system is another common structural system in high-rise
buildings. The vertical core elements mostly consist of concrete shear walls or braced
system to resist lateral loads. The outriggers are generally in the form of trusses in steel
structures, or walls in concrete structures, which extend on both sides from the central core
connecting the core to the perimeter of the building. The existence of outriggers can reduce
the overturning moment in the core and can transfer the reduced moment to the outer
elements as shown in Figure 10 (Taranath, 1998).
Shear wall or
braced frame
core
Column
20
Outrigger
truss
connected
directly
to core
_F
Moment in core with
--
+
\outrigger
Leeward
columns in
compression
bracing
\.--Moment in core without
outrigger bracing
Windward
columns in
tension
Figure10: Core and outriggersystem.
Belt trusses are often combined in core and outrigger systems to distribute the
tensile and compressive forces to a large number of exterior frame columns, which are
located at the perimeter of the structure. Belt trusses also help in minimizing differential
elongation and shortening of columns. In the design of existing high-rise buildings,
outriggers are also supported by mega-columns in the exterior perimeter of the structure.
Some other advantages of the core and outrigger system includes that the exterior
column spacing can satisfy more aesthetic and functional requirements. For the aspect of
construction, the exterior framing system consists of simple beams and columns and does
not require moment-resisting connections as in rigid frame system, which is beneficial to the
construction process.
The core and outrigger system may be formed in any combination of steel, concrete
21
and composite construction. Because of the structural benefits of this system and the
advantages listed above, the core and outrigger system has been very popular over the past
decade.
3.2.3 Framed Tube
The framed tube system is the most basic tubular system in high-rise buildings.
The tubular system expresses the concept that a building can be designed as a
hollow cantilever perpendicular to the ground to resist lateral loads by designing it. In the
simplest framed tube system, the exterior perimeter of the structure consists of closely
spaced columns that are tied together with deep spandrel beams through moment
connections (Figure 11).
Closely spaced columns
I
:b
Figure 11: Framed tube system.
22
For a framed tube under lateral loads, the corner columns experience the largest
axial forces, and forces are distributed non-linearly along the direction parallel to wind and
perpendicular to wind. This is because the axial forces in the middle columns of the frame
lag behind that in the corner columns because that the structure acts like a hollow tube
instead of a solid one. This phenomenon is called the shear lag effect, as shown in Figure 12.
In the design of framed tube system, the optimal purpose if to limit the shear lag effect.
Cosrmpive
Figure 12: Shear lag effect.
3.2.4 Trussed Tube
The trussed tube is a variation of the framed tube system. By adding large truss
elements around the perimeter of the tube system, the bending stiffness of the structure can
be increased, and the number of exterior columns can be decreased. The truss elements can
also transfer some of the gravity loads acting as inclined column. At the same time, the
23
diagonals of a trussed tube connected to the joints of columns and beams effectively
eliminate the effects of shear lag around the structure. Therefore, the space of columns in the
perimeter of the building can be arranged more widely and the sizes of spandrel beams and
columns can be designed smaller than the framed tubes (Khan, 1967).
Innovative structural systems over the past decade include diagrid systems and
hexagrid systems (Figure 13). The difference between conventional trussed tube structures
and the diagrid system is that almost all conventional vertical columns can be eliminated for
diagrid structures. This is because the diagonal members in diagrid structural systems can
carry both gravity loads and lateral loads through their triangulated configuration (Panchal
and Patel, 2014). The hexagrid system, also called beehive system, is another evolutionary
structural system in the design of high-rise buildings. In addition to eliminating perimeter
columns, another noticeable advantage of the hexagrid systems is that each structural
element can be optimized. This is a relatively new idea and more exploration is required for
the implement of this structural system in the design of high-rise buildings (Askarinejad,
2012).
Z
Z
N
N/
NZ
NZ
4 N
I
Figure 13: Trussed tube systems (Left: conventional trussed tube; middle: diagridsystem;
24
right: hexagrid system).
3.2.5 Tube in Tube
The tube in tube system uses the core to resist part of the lateral loads in order to
enhance the stiffness of the tubular systems. This structural system consists of an outer tube
in the perimeter and a core tube inside the structure. The core tube inside could be made of a
framed tube, a trussed tube or a solid tube holding elevators and other services. The floor
system connecting the core and the exterior tube transfers the lateral loads to both systems,
while the exterior tube system carries more loads because its greater structural stiffness
(S.R.S.Kuman and A.R.S. Kuman, 2014).
The tube in tube system is flexible in materials because the two tube systems can be
constructed using completely different materials. Current designs of high-rise buildings
combine concrete shear wall core with outer steel framed tube, which is an efficient system
in resisting of different types of loads and has been widely implemented. Figure 14 shows
the floor plan of a typical tube in tube structure, which is the China Trade Center, located in
Beijing, China. The structure of this building consists of a concrete core and the exterior
steel framed tube.
25
Figure 14: Floorplan of typical tube in tube system.
3.2.6 Bundled system
The bundled tube structural systems in a combination of several individual tubes
connected together to act as a single unit. The structural stiffness of the building is notably
increased. In this system, the shear lad effect in the flanges is largely reduced by the
existence of the internal webs. The bundled tube system also allows wider column spacing
in the tubular walls, and the stress in columns is distributed more evenly than that in a single
tube system.
One of the most typical bundled tube systems is the 110-story Willis Tower
completed in 1974 which was also the first buildings using such systems. There are nine
steel framed tubes in total bundled at the bottom of the buildings and they are terminated in
different heights as Figure 15 shows. Such structural system provides the high-rise building
with new possible appearance instead of the simple boxlike shape.
26
D
110
90
Section D-D
66
Section C- C
50
30
Section 8 B
A
Section A-A
Figure 15: Structuralsystem of Willis Tower.
One innovative structural system using the bundled form over the past decade is the
buttressed core system, which was implemented in the design of Burj Khalifa. The most
important factor of this system is a tripod-shape structure in which a strong concrete core in
the center anchors three structural elements arranged around it. The structure of Burj Khalifa
will be discussed more in the case study section later.
27
4. INNOVA TIONS IN HIGH-RISE B UILD GINS
4.1 Damping Systems
As the evolution of structural systems and development in construction materials
especially high-strength concrete, the weight of the high-rise building has been decreased
considerably than that of earlier ones. Lighter structures reduce cost as well as the
construction time. However, they may cause serious structural motion problem due to the
wind load. An implement of damping systems will help control the structural motion.
Damper can reduce not only the amount of lateral displacement but also the acceleration of
the structure. Structures with more damping can reduce the magnitude of vibration and
dissipate the vibration more quickly (Moon, 2005).
Damping system can be divided into two categories, passive damping systems and
active damping systems. Passive damping systems have fixed properties and they do not
need energy to perform as intended, while active damping systems do need energy input
serving as actuators to modify the damping system properties under different load cases.
Therefore, active damping systems are more efficient than passive systems. However,
passive damping systems are more commonly used in high-rise buildings because of the cost
and reliability.
Passive damping systems can be further divided into two subcategories, auxiliary
mass systems to generate counteracting forces such as tuned mass dampers (TMD) and
tuned liquid dampers (TLD), and energy dissipating materials based systems such as viscous
28
dampers and visco-elastic dampers.
Active damping systems are a more advanced form of performance driven
technologies, which is the tendency of today's high-rise building design. Examples include
active mass dampers (AMD) and active variable stiffness devices (AVSD). Different types
of auxiliary damping systems are summarized in Figure 16 (Connor, 2003).
Tuned Mass Dampers ( TMD)
Tuned Lquid Dampers (TLD)
Vicus Dampers_
Passive System
Viscoelassk Dampers
Hysteretic Dampers
Fricton Dampers
-Etem4Aagne
Dampers
Active Mass Dampers (AMD)
Acive
System
Acive Various Stifless (AVS) Devices
Figure 16: Various types of auxiliary dampingsystems.
However, it is noticeable that as the continuously evolvement of structural systems
more and more high-rise buildings do not need additional damping systems anymore. The
property of the structure itself is sufficient to protect the building from vibrations due to
29
wind. Such structural factors that will help decrease the dependence of high-rise buildings
on auxiliary damping systems include bundled systems, twisted shape of the building and
opening at the top, as shown in Figure 17. Trump Tower, which is located in Chicago,
implemented no additional damping systems. The stiffness and weight of the building,
combined with the asymmetric setbacks, laterally support and stabilize the tower ad
minimize perceptible motion.
Figure17: Buildings using geometries to reduce reliance on auxiliary dampingsystems (left
1 &2: bundled systems; middle: opening at top; right 1 &2: twisted shapes).
4.2 Construction Techniques
While structural engineers managed to find a plan for buildings to rise out of the
ground theoretically or experimentally, it still remains a challenge for contractor to actually
30
build it. As the height of high-rise buildings increases, so does the challenge contractors face.
Construction teams not only have to erect steel and concrete members, they also have to do
it precisely, safely, time and cost efficiently and environmentally friendly. Therefore,
construction techniques have to be developed.
Being time efficient not only means that the building can open to public sooner, but
also means lower construction cost. An innovation applied in the construction of the Shard
in London is the top-down construction method. It allowed the first 23 stories of the
concrete core and much of the surrounding tower to be built before the basement had been
fully excavated. This technique was a world first and saved four months time and a huge
amount of budget on the complex program.
As the development
of construction materials especially the creation of
high-strength concrete, more and more high-rise buildings start to use concrete to construct
the structure. Having more powerful pump means high that high-strength concrete is able be
delivered to high levels at greater speed. The KK100 in Shenzhen set a record of pumping
high-strength C 120 grade concrete to the height of 417 meters.
To guarantee workers' safety, precaution for hazard prevention has to be taken
seriously. During construction of Doosan Haeundae We've the Zenith Tower, to prevent
spalling, which is the explosion that can occur when the concrete is exposed to high
temperatures, contractors built the tower with high strength concrete using a spalling failure
prevention method.
31
To make sure the building is in its upright position, GPS technology has been used
over the past decade. This would not have been possible before satellites and GPS
technologies were mature. The Al Hamra Tower, which is located in Kuwait City, utilized
Leica Geosystems Core Wall Survey Control System, a procedure developed by Leica
Geosystems using GPS observations combined with a precision inclination sensor to provide
reliable coordinated points at the top of the building. Another example is used in the
construction of Almas Tower in Dubai, where vortex shedding suppression devices based on
simple principles were used as temporary measures during the construction stage to prevent
excessive wind induced movement of the spire.
4.3 Elevator Systems
As the height of high-rise building increases rapidly, the upgrade of many of its
accessories is required. One of the developed accessories is the elevator system. For
high-rise buildings, efficient mobility is an absolute necessity. Past elevators are
incompatible with today's super-tall buildings, as they have relatively slow rising and
descending rates, causing much time loss when traveling between high levels; some elevator
shafts are so large in size that they take up much of the level's space; some buildings are so
tall that the steel elevator cables are close to the limit where they can no more carry their
own weight.
During the past decade, various technical advancements are seen in the elevator
32
system of high-rise buildings. One smart design is the double deck elevator (Figure 18). As
the name indicates, the double deck elevator consists of two individual cars attached
together, one on top of the other. Both cars operate in the same elevator shaft. Such a
scheme could increase efficiency dramatically during high traffic periods. During such time,
single elevator would stop at every floor, but the double deck elevator will only stop at every
other floor as one of its cars transport passenger on odd floors and the other transport
passengers on even floors. Besides the improved efficiency in elevator shaft usage, the
operation speed of the elevator has also increased throughout the years. Table 1 below
shows the comparison of elevator speed of some of the world's famous buildings. It can be
seen that the speed has increased in the last few decades. The improvement in elevator speed
is accompanied by more powerful magnetic motors, high-tech air pressure adjustment
systems, and lighter and stronger materials. Finnish manufacturer Kone has developed a
carbon fiber dubbed UltraRopeTM that is seven times lighter than steel cables (Figure 19).
The UltraRopeTM will be used in the 1000-meter-tall Kingdom Tower, Saudi Arabia, which
is under construction.
Currently, engineers are picturing elevator systems that will travel both vertically
but also horizontally. As elevators will carry passengers horizontally, vertical shafts could be
reduced, thus saving floor spaces. ThyssenKrupp is poised to revolutionize elevator power
system by using magnetic drive similar to that seen on a Maglev train. The system will be
the world's first cable-free elevator and counter-weight free.
33
Building
Completion Year
Elevator Speed (m/s)
Chrysler Building, New York City
1930
4.5
Empire State Building, New York City
1931
7.1
Willis Tower, Chicago
1974
8.1
Taipei 101, Taiwan China
2004
16.8
Shanghai Tower, Shanghai
2015
18
CTF Finance Tower, Guangzhou
2016
20 (expected)
Table 1: Comparisonof elevator speed of some of the worlds famous buildings.
Coss,
440.MV *kVWwwM
-of
NWe-
we-IR010
Figure 18: Scheme ofdouble deck elevator
Elevator moving masses (kg)
108600
13900
Steel Cable
UltraRope"
.
Figure 19: Comparisonof traditionalsteel cable to Kone UltraRopeT M
34
4.4 Sustainability
Over the past decades, more and more factors besides structural and constructional
aspects are taken into consideration in the design of high-rise buildings. As global warming
and fossil fuel are becoming increasingly concerned topics, engineers are challenged to put
further effort into designing buildings that are more environmentally friendly. Measures that
care most commonly seen in achieving the sustainability of high-rise buildings can be
categorized into two aspects - constructional and operational.
Constructional sustainability is the measures taken during the construction process.
These measures include purchasing construction materials locally or regionally, thus
reducing total mileage of transportation, which in turn reduced carbon footprint. Another
measure is to reuse and recycle excess materials. In excess of 95% of structural steel was
recycled after the construction of New York Times Building, New York City.
Analogously, operational sustainability indicates the measures taken after the
completion of construction and during its normal operation. One of the most common
measure is the use of double-sided windows or double wall curtains with low-emissivity
coating to improve thermal insulation (Figure 20). Additionally, use of LED lights for
signage will reduce electricity consumption significantly. The Shanghai World Financial
Center features over 7000 LEDs, and the power consumption for its signage is merely 220
KW, which is much lower than even the shorter buildings around it. Buildings by rivers or
seas can reduce energy cost by using river or seawater to cool the buildings. An example is
35
the Trump Tower in Chicago that utilizes water from the Chicago River to cool the building.
The cooling system allows the water to recirculate back to the river. Building in high
sunshine areas can install solar panel to heat water. Bun Khalifa features solar panels that
are capable of heating 140,000 liters of water daily. In cities where pollution is heavy,
buildings have air filtration and circulation system to guarantee occupants breathe clean air.
In recognition of and to promote sustainability in building, the U.S Green Building Council
(USGBS) awards the Leader in Energy and Environmental Design (LEED) certificate to
buildings that are outstanding in sustainability. The certification has four levels - certified,
silver, gold, and platinum. The Taipei 101, which is located in Taipei City, has been
awarded the LEED Platinum certificate and will set the quality and performance benchmark
for super-tall buildings.
Figure 20: Double skinnedfacade curtain wall system.
36
5. ANALYSIS OF CURRENT HIGH-RISE BUILDINGS
To better understand the implement of different structural systems, construction
materials and design critics of high-rise buildings in the actual world, information about
high-rise buildings above 200 meters completed in the past ten years as well as the current
100 tallest buildings in the world has been collected and analyzed.
5.1 Structural Systems
Based on the properties of different types of structural systems which are
introduced in previous section, structural systems of modem high-rise buildings are divided
into seven categories: rigid frames, core and outrigger systems, framed tubes, trussed tubes,
tube in tube systems and bundle systems. The results have been shown in Figure 21 and
Figure 22.
Figure 21 shows the distribution of structural systems of high-rise buildings above
200 meter completed during each period over time. As the figure shows, tube in tube
systems have been more and more used in the design of high-rise buildings, while rigid
frame systems is no more been used within the past five decades.
Figure 22 shows the distribution of structural systems of the current worldwide 100
tallest buildings. As can be seen, vast majority of the structural system consist of tubular
systems and core and outrigger systems, in which the tube in tube system has the largest
percentage of 38%.
37
16
14
12
"
10
Bundled system
" Tube in tube
" Trussed tube
-
5*
" Framed tube
6
N Core and outrigger
4,
* Rigid Frame
...
...
2...
Figure 21: Distributionof structuralsystems of buildings over 200m over time.
2%
0 Bundled system
U Tube
intube
8 Trussed tube
a Framed tube
M Core and outrigger
0 Rigid Frame
Figure 22: Distributionof structuralsystems of the current 100 tallest buildings.
Taking the average stories of different types of structural systems of the current 100
tallest buildings in the world, comparison can be conducted with previous theoretical
analysis of structural systems. As Figure 23 shows, bundle system has the highest average
38
number of stories, while core and outrigger system has the lowest average number of stories.
Rigid frame system has the second highest average number of stories, which is quite
different from previous analysis, because of relatively small sample size.
100
90
;
80
70
60
s0
40
30
20
10
0
Core and
outrigger
Tube in
tube
Framed
tube
Trussed
tube
Rigid
Frame
Bundled
system
Figure 23: Average number of stories of different types of structuralsystems.
5.2 Construction Materials
To study the trend of construction materials, information about worldwide 100
tallest buildings in each period is collected. Result is shown in Figure 24.
A steel building is defined as a building where the main vertical and lateral
structural elements and floor systems are constructed from steel. Similarly, a concrete
building is defined as one where the main vertical and lateral structural elements and floor
systems are constructed from concrete. A composite building utilizes a combination of both
steel and concrete acting compositely in the main structural elements. A mixed-structure
39
building is any building that utilizes distinct steel and concrete systems above or below each
other.
As the figure indicates, a high percentage of buildings are using composite materials
in the past few decades. The most common combination is a steel building with a concrete
core. At the same time, the number of buildings using concrete as the construction materials
is increasing as well. One possible reason behind the increasing number of concrete
buildings is the development of high-strength concrete and concrete pumping techniques
which have been discussed previously.
100
* Unknown
75
"
50
Mixed
a Composite
" Concrete
25
" Steel
0
1960
1970 1980 1990 2000 2005
2010 2015
Figure 24: Distributionof construction materials of 100 tallest buildings in each
period.
5.3 Sustainability
Since the matter of sustainability has been given more and more consideration in
recent years, the sustainable design of 72 buildings completed in the past decade that are
40
listed in the current 100 tallest buildings is studied besides the aspects of structural systems
and construction materials. Result is shown in Figure 25.
As the result shows, 43 percent of buildings have considered sustainability in their
design, and most of them are awarded LEED certificates. According to the data collected,
most popular measures of sustainable design of high-rise buildings include double-sided
windows or double curtain walls to provide thermal protection and water recycling and air
filtration systems.
* Number of buildings
considering
sustainability
* Number of buildings
without considering
sustainability
Figure 25: Distribution of buildings consideringsustainability.
41
6. CASE STUDY OF BURJ KHALIFA
At 828 meters, the Burj Khalifa (formerly the Burj Dubai) has 163 stories and is the
world's tallest freestanding structure as well as the world's tallest building (Figure 26).
Construction of the tower began in January 2004 and the structure was topped out in
October 2009. It was officially opened in January 2010. The architectural and engineering
designer of this tower was Skidmore, Owings and Merill (SOM) of Chicago and its primary
contractor is Samsung Engineering and Construction Group of South Korea.
Figure 26: Bur Khalifa.
The structural system of Buj Khalifa is buttressed core system that is mentioned
above. It is designed to efficiently support a super-tall building utilizing a strong central core,
buttressed by its three wings. The vertical structure is tied together at the mechanical floors
through outrigger walls in order to maximize the building's stiffness. It is an inherently
42
stable system in that each wing is buttressed by the other two. The central core provides the
torsional resistance for the building, while the wings provide the shear resistance and
increased moment of inertia. The result is an efficient system where all of the building's
vertical structure is used to resist both gravity and lateral loads (Figure 27).
wing
central core
corridor wall
Figure 27: Typicalfloorplan of Bur Khalifa.
The structural integrity of the building itself can also serve as the damping system.
The building rises to the heavens in several separate stalks, which top out unevenly around
the central spire. This somewhat odd-looking design deflects the wind around the structure
and prevents it from forming organized whirlpools of air current, or vortices, that would
rock the tower from side to side and could even damage the building. The variation of the
tower shape, and width, resulted in wind vortices around the perimeter of the tower that
behaved differently for different shapes at different frequencies, thus disorganizing the
43
interaction of the tower structure with the wind (Figure 28). Over 40 wind tunnel tests were
conducted on Burj Khalifa to examine the effects wind would have on the tower and its
occupants. Engineers determined that no tuned-mass damping was needed.
VM
T~-
PWoo
Lower
Pan
Figure 28: Wind profile aroundBur] Khalifa.
During the construction process, over 45,000 m3 of concrete weighing more than
110,000 tons were used to construct the concrete and steel foundation, which features 192
piles. Each pile is 1 .5m in diameter and 43m long buried more than 50m deep. The
construction of Burj Khalifa's used 330,000 m3 of concrete and 39,000 tons of steel rebar.
Special mixes of concrete are made to withstand the extreme pressure of the massive
building. It was difficult to create a concrete that could withstand both thousands of tons
bearing down on it and high Persian Gulf temperatures that can reach 50 0C (122 0F). To
44
combat this problem, the concrete was not poured during the day. Instead, it was poured at
night when the air is cooler and the humidity is higher, and during the summer months ice
was added to the mixture. In November 2007, the highest reinforced concrete core walls
were pumped using 80 MPa concrete from ground level to the height of 606 meters, which
broke the previous pumping record of 470m in the Taipei 101.
At the aspect of elevator systems, eight escalators and 57 elevators were installed in
Burj Khalifa, of which two are double-deck elevators used exclusively for the travel to the
observation deck. Engineers of Bun Khalifa considered triple deck elevators at first, but the
final design called for double deck elevators. With the rising and descending speed up to
1Om/s, these are the world's fastest double-deck elevators. The elevator system of this tower
is also awarded as the longest travel distance elevator in the world that is 504 meters, and the
world's highest elevator which lands at 638 meters (Otis, 2010).
Burj Khalifa is also considered as a sustainable building. Solar panels are capable of
heating 140000 liters of water daily. A special performance glazing glass with low
emissivity provides the tower with advanced thermal protection. Due to its significant height,
the building is able to utilize ventilation from where air temperature is cooler and humidity
is relatively lower. When air is drawn in at the top of the building, it requires less energy for
air conditioning, ventilation, and dehumidification system. LED modules used for signage
throughout to ensure reliable low maintenance lighting with low energy consumption.
Additionally, Burj Khalifa has one of the largest condensate recovery systems in the world.
45
Collecting water from air conditioning condensate discharge prevents it from entering the
wastewater stream and reduces the need for municipal potable water (Burj Khalifa,
CTBUH).
46
7. CONCLUSION
Over the past decade, both the number of high-rise buildings and the average height
of high-rise buildings have increased rapidly. Continuously evolving structural systems
creates opportunities for structures to be more efficient. Other developments in construction
techniques, accessory systems as well as structural materials have enabled the structure to
actually stand taller and taller.
Based on the study of recent high-rise buildings and the current 100 tallest buildings
in the world, following trends can be summarized: By the year of 2015, tubular structures
are in vast majority of the structural systems in recent high-rise buildings, in which tube in
tube system is the most popular one and has been applied in the design of a large number of
high-rise buildings. Advancements in structural systems also help to reduce buildings'
dependence on auxiliary damping devices. For structural materials, there is an increasing
trend to use concrete and composite materials to construct the structure. Additionally,
sustainability has been given more consideration in modem high-rise building designs.
47
Al. REFERENCES
Ali, Mir M.; Moon, Kyoung Sun (2007). "Structural Developments in Tall Buildings:
Current Trends and Future Prospects". ArchitecturalScience Review 50 (3): 205-223.
Ali, M.M. (2001). "Art of the Skyscraper: The Genius of Fazlur Khan". New York: Rizzoli.
Askarinejad,
P. (2012). "Beehive
(Hexagrid):
Innovative
Structural
System
of Tall
Buildings". Council on Tall Buildings and Urban Habitat.
Baker, W. F. (2001). "Structural Innovation." Sixth World Congress on Tall Buildings and
Urban Habitat. Melbourne, Australia.
Challinger, D. "From the Ground Up: Security for Tall Buildings CRISP Report".
Alexandria, VA: ASIS Foundation Research Council; 2008.
Connor, J.J. (2003). Introductionto StructuralMotion Control.
Hall, Jr JR (2005). "High-Rise Building Fires". Quincy, MA: National Fire Protection
Association.
Khan, F.R. (1967). "The John Hancock Center". Civil Engineering, 37(10), 3 8-42.
Khan, F.R. (1969).
"Recent structural systems in steel for high-rise buildings". In
Proceedings of the British Constructional Steelwork Association Conference on Steel in
Architecture. London: British Constructional Steelwork Association.
Khan, F.R. (1972). "Influence of design criteria on selection of structural systems for tall
buildings". In Proceedings of the Canadian Structural Engineering Conference. Toronto:
Canadian Steel Industries Construction Council, 1-15.
Khan, F.R. (1973). "Evolution of structural systems for high-rise buildings in steel and
concrete". In J. Kozak (Ed.), Tall Buildings in the Middle and East Europe: Proceedings
of the 10th Regional Conference on Tall Buildings-Planning, Design and Construction.
Bratislava: Czechoslovak Scientific and Technical Association.
Kumar,
S.R.S.;
Kumar,
A.R.A.. "Advanced
structural
forms". Design
of
Steel
Structures. Indian Institute of Technology Madras.
Moon, K. (2005). "Dynamic Interrelationship between Technology and Architecture in Tall
Buildings". Unpublished PhD Dissertation, Massachusetts Institute of Technology.
48
Otis (2010). "Burj Khalifa, the world's tallest building, inaugurated: Global press and first
deck".
observation
to
elevators
Otis
ride
visitors
<http://www.otis.com/_layouts/ProjectNewsPopup.aspx?ID= 1 3&siteURL=http://www.ot
is.com/site/in/pages/OtisNews.aspx> (May 20, 2015)
Panchal, N.B.; Patel,V.R. (2014). "Diagrid structural system: strategies to reduce lateral
forces on high-rise buildings". InternationalJournal of Research in Engineering and
Technology, Volume: 03 Issue: 04
Schueller, W. (1986). High-Rise Building Structure (2nd ed). Malabar, Florida: Krieger.
Taranath, B. S. (1998). Steel, Concrete, & Composite Design of Tall Buildings. Second
Edition. McGraw-Hill. New York, NY.
49
A2. 100 TA LLEST BUILINGS IN THE WORLD BY 2015
Building Name
City
Height
(m)
Floors
Completed
Material
1
Buj Khalifa
Dubai (AE)
828
163
2010
steel/concrete
2
Shanghai Tower
Shanghai (CN)
632
128
2015
composite
Mecca (SA)
601
120
2012
steel/concrete
541.3
94
2014
composite
Taipei (TW)
508
101
2004
composite
Shanghai (CN)
492
101
2008
composite
Hong Kong (CN)
484
108
2010
composite
451.9
88
1998
composite
451.9
88
1998
composite
#
3
Makkah Royal Clock
Tower Hotel
4
One World Trade Center
5
TAIPEI 101
6 6 Shanghai World Financial
New York
City (US)
Center
International Commerce
Centre
7
8
Petronas Tower
1
_____Lumpur
9
Petronas Tower 2
Kuala
(MY)
Kuala
(MY)
_____Lumpur
10
Zifeng Tower
Nanjing (CN)
450
66
2010
composite
11
Willis Tower
Chicago (US)
442.1
108
1974
steel
12
KK100
Shenzhen (CN)
441.8
100
2011
composite
Guangzhou (CN)
438.6
103
2010
composite
13
13 Guangzhou Intemnational
Cnter
Finance Center
14
Marina 101
Dubai (AE)
426.5
101
2015
concrete
15
432 Park Avenue
New York (US)
425.5
88
2015
concrete
Chicago (US)
423.2
98
2009
concrete
16
16 Trump International Hotel
ter
& Tower
17
Jin Mao Tower
Shanghai (CN)
420.5
88
1999
composite
18
Princess Tower
Dubai (AE)
413.4
101
2012
steel/concrete
19
Al Hamra Tower
Kuwait City (KW)
412.6
80
2011
concrete
Two International Finance
20
Centre
Hong Kong (CN)
412
88
2003
composite
21
23 Marina
Dubai (AE)
392.4
88
2012
concrete
22
CITIC Plaza
Guangzhou (CN)
390.2
80
1996
concrete
23
Capital Market Authority
Tower
Riyadh (SA)
385
76
2015
composite
24
Shun Hing Square
Shenzhen (CN)
384
69
1996
composite
50
25
Eton Place Dalian Tower 1
Dalian (CN)
383.1
80
2015
composite
26
Burj Mohammed Bin
Rashid Tower
Abu Dhabi (AE)
381.2
88
2014
concrete
27
Empire State Building
New York
City (US)
381
102
1931
steel
28
Elite Residence
Dubai (AE)
380.5
87
2012
concrete
29
Central Plaza
Hong Kong (CN)
373.9
78
1992
Moscow (RU)
373.7
95
2015
Concrete
Federation Towers
Vostok Tower
31
Bank of China Tower
Hong Kong (CN)
367.4
72
1990
composite
32
Bank of America Tower
New York (US)
365.8
55
2009
composite
33
Almas Tower
Dubai (AE)
360
68
2008
concrete
34
JW Marriott Marquis
Hotel Dubai Tower 1
Dubai (AE)
355.4
82
2012
concrete
35
JW Marriott Marquis
Hotel Dubai Tower 2
Dubai (AE)
355.4
82
2013
concrete
36
Emirates Tower One
Dubai (AE)
354.6
54
2000
composite
37
OKO - South Tower
Moscow (RU)
353.6
85
2015
concrete
38
The Torch
Dubai (AE)
352
86
2011
concrete
Shenyang (CN)
350.6
68
2015
composite
-
30
39
Forum 66 Tower
1
concrete
40
The Pinnacle
Guangzhou (CN)
350.3
60
2012
concrete
41
T & C Tower
Kaohsiung (TW)
347.5
85
1997
composite
42
Aon Center
Chicago (US)
346.3
83
1973
steel
43
The Center
Hong Kong (CN)
346
73
1998
steel
44
John Hancock Center
Chicago (US)
343.7
100
1969
steel
45
ADNOC Headquarters
Abu Dhabi (AE)
342
76
2015
concrete
Dubai (AE)
342
76
2015
steel/concrete
Wuxi (CN)
339
68
2014
composite
World
Chongqing
Cnr
F in
Chongqing (CN)
338.9
72
2015
composite
Mercury City Tower
Moscow (RU)
338.8
75
2013
concrete
Tianjin (CN)
S
C
336.9
3
2011
composite
Shanghai (CN)
333.3
75
6
60
2006
concrete
Ahmed Abdul Rahim Al
46
Aed
Wuxi International
Finnaioal
47
48
49
50
51
Tb wer
Attar Tower
Finance Square______________
48
Financial Center
50 Tianjin World Financial
Center
P
Shimao International Plaza
51
52
Rose Rayhaan by Rotana
Dubai (AE)
333
71
2007
composite
53
Minsheng Bank Building
Wuhan (CN)
331
68
2008
steel
54
China World Tower
Beijing (CN)
330
74
2010
composite
Hanoi (VN)
328.6
72
2012
concrete
55
Keangnam Hanoi
Landmark Tower
56
Longxi International Hotel
Jiangyin (CN)
328
72
2011
composite
57
Al Yaqoob Tower
Dubai (AE)
328
69
2013
concrete
58
Wuxi Suning Plaza
Wuxi (CN)
328
68
2014
composite
1
59
The Index
Dubai (AE)
326
80
2010
concrete
60
The Landmark
Abu Dhabi (AE)
324
72
2013
concrete
61
Deji Plaza
Nanjing (CN)
324
62
2013
composite
Yantai (CN)
323
59
2015
composite
62
Yantai Shimao No. 1 The
Harbour
63
QI Tower
Gold Coast (AU)
322.5
78
2005
concrete
64
Wenzhou Trade Center
Wenzhou (CN)
321.9
68
2011
concrete
65
Burj Al Arab
Dubai (AE)
321
56
1999
composite
66
Nina Tower
Hong Kong (CN)
320.4
80
2006
concrete
67
Chrysler Building
New York
City (US)
318.9
77
1930
steel
68
New York Times Tower
318.8
52
2007
steel
Wuhu (CN)
318
66
2015
composite
69
Riverside Century Plaza
Main Tower
New York
City (US)
70
HHHR Tower
Dubai (AE)
317.6
72
2010
concrete
71
Bank of America Plaza
Atlanta (US)
311.8
55
1992
composite
72
Moi Center Tower A
Shenyang (CN)
311
75
2014
composite
73
U.S. Bank Tower
Los Angeles (US)
310.3
73
1990
steel
74
Menara Telekom
310
55
2001
concrete
75
Ocean Heights
Dubai (AE)
310
83
2010
concrete
76
Pearl River Tower
Guangzhou (CN)
309.4
71
2013
composite
77
Fortune Center
Guangzhou (CN)
309.4
73
2015
composite
78
Emirates Tower Two
Dubai (AE)
309
56
2000
concrete
79
Burj Rafal
Riyadh (SA)
307.9
68
2014
concrete
Tower
Chicago (US)
Chi (U)
306.9
306.9
60
60
1989
1989
Cayan Tower
Dubai (AE)
306.4
73
2013
80
81
52
The Franklin - North
Kuala
Lumpur (MY)
composite
composte
concrete
82
One57
New York (US)
306.4
75
2014
steel/concrete
83
East Pacific Center Tower
A
Shenzhen (CN)
306
85
2013
concrete
84
The Shard
London (GB)
306
73
2013
composite
85
JPMorgan Chase Tower
Houston (US)
305.4
75
1982
composite
86
Etihad Towers T2
Abu Dhabi (AE)
305.3
80
2011
concrete
Incheon (KR)
305
68
2011
composite
Bangkok (TH)
304
85
1997
concrete
Wuxi (CN)
303.8
68
2014
composite
87
Northeast Asia Trade
t
e
Tower
r
88
Baiyoke Tower II
89
Wuxi Maoye City
Marriott Hotel
-
90
Two Prudential Plaza
Chicago (US)
303.3
64
1990
concrete
91
Shenzhcn Changcheng
Center
Shenzhen (CN)
303
61
2014
composite
92
Greenland Puli Center
Jinan (CN)
303
60
2015
composite
93
Leatop Plaza
Guangzhou (CN)
302.7
64
2012
composite
94
Wells Fargo Plaza
Houston (US)
302.4
71
1983
steel
95
Kingdom Centre
Riyadh (SA)
302.3
41
2002
steel/concrete
96
The Address
Dubai (AE)
302.2
63
2008
concrete
Moscow (RU)
301.8
76
2010
concrete
97
Capital City Moscow
Tower
98
Aspire Tower
Doha (QA)
300
36
2007
composite
99
Arraya Tower
Kuwait City (KW)
300
60
2009
concrete
Busan (KR)
300
80
2011
concrete
Doosan Haeundae We've
100
the Zen
We
the Zenith Tower A
53