Keynote Lecture
CIB2004 World Building Congress
Toronto, Ontario CANADA
May 2-7, 2004
High-Rise Buildings:
Evolution and Innovations
Dr. Oral Buyukozturk
Professor of Civil and Environmental Engineering
Oguz Gunes
Ph.D. Candidate
Massachusetts Institute of Technology
Cambridge, MA, USA
OUTLINE
• INTRODUCTION
• LOADS
• EVOLUTION
• INNOVATIONS
• CONCLUSION
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
Introduction
What is a high-rise building?
“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.”
The Council of Tall Buildings
and Urban Habitat
Introduction
Introduction
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
Demand for High-Rise Buildings
• Scarcity of land in urban areas
• Increasing demand for business and residential
space
• Economic growth
• Technological advancements
• Innovations in Structural Systems
• Desire for aesthetics in urban settings
• Concept of city skyline
• Cultural significance and prestige
• Human aspiration to build higher
Introduction
Introduction
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
Geographical Distribution of High-Rise Buildings
(Tables source: Emporis Corporation April 2004)
Introduction
Introduction
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
Economy vs. Demand for High-Rise Buildings
Economic growth and resulting demand for office space is a good
indication of demand for high-rise buildings
U.S. Asking Office Rents, Class A
U.S. Gross Domestic Product
10%
8%
6%
4%
2%
0%
-2% 2001
$ Per Sq. Ft. Per Year Full Service
CBD
Suburban
$50
$40
$30
2002
2003
2004
$20
Jan-98Jan-99Jan-00Jan-01Jan-02Jan-03Jan-04
U.S. Office Supply vs. Demand
U.S. Office Vacancy Rates
19.0%
17.0%
15.0%
13.0%
11.0%
9.0%
7.0%
5.0%
86 88
90
92 94 96
98 00
Sq. Ft. in Millions
150
100
50
0
-50
-100
02 04
Completed
Absorbed
86 88 90 92 94 96 98 00 02 04
(Grubb & Ellis Company, 2004)
Introduction
Introduction
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
Structural Loads
Snow Load
• Gravity loads
– Dead loads
– Live loads
– Snow loads
Impact
Load
Dead Loads
• Lateral loads
– Wind loads
– Seismic loads
Wind Load
Live Loads
• Special load cases
– Impact loads
– Blast loads
Blast
Load
Earthquake Load
Introduction
Introduction
Loads
Loads
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
Gravity Loads
•
•
•
Floor systems account for a major portion of the gravity loads
Selection of the floor system may influence structural behavior
and resistance
Structural use plays a major role in selection of the floor system
– Office buildings
• large simply supported spans
– Residential and hotel buildings
• short continuous spans
Types of floor systems
• Concrete
• Prestressed concrete
• Steel
• Composite
Introduction
Introduction
Loads
Loads
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
Wind Loads
Qh
Qz
Qz
Qh
Plan view
z
Qh
H
Qh
Wind
ch
(S
7)
97
1
r,
lle
e
u
Qz = KV I
2
Qh = Qz
z=H
(Taranath, 1998)
Introduction
Introduction
Loads
Loads
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
Seismic Loads
Spectral response
acceleration (g)
Response with
increasing damping
W
0
V
2
4
6
8
Period
(sec)
V = Cs × W
Decreasing V/W
Introduction
Introduction
Loads
Loads
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
Design for Increased Height
• Building weight and cost increase nonlinearly with increasing
height due to lateral loads
• Efficient structural and material systems are needed to reduce
weight and cost
• Wind loads generally govern design for lateral loads for heights
• > 150 m for steel buildings
• > 250 m for concrete buildings
(Ali, M., 2001)
Introduction
Introduction
Loads
Loads
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
Evolution of Structural Systems
A clear classification of high-rise buildings with respect to their
structural system is difficult
A rough classification can be made with respect to effectiveness
in resisting lateral loads
Structural Systems
•
•
•
•
Moment resisting frame systems
Braced frame, shear wall systems
Core and outrigger systems
Tubular systems
– Framed tubes
– Trussed tubes
– Bundled tubes
• Hybrid systems
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
Evolution of Structural Systems
•
•
•
•
•
•
•
• • •
• • •
• • •
• • •
• • •
• • •
• • •
•
•
•
•
•
•
•
Type I
Introduction
Introduction
• • •
• • •
• • •
• • •
• • •
• • •
• • •
•
•
•
•
•
•
•
• • •
• • •
• • •
• • •
• • •
• • •
• • •
Type II
Loads
Loads
•• • •• • ••
•
•
•
•
•
•
•
•
•
•
•
• • • • • • • ••
Type III
Evolution
Evolution
Evolution
Evolution
•• • •• • •
•• •• ••
•• •• ••
•• • •• • •
Exterior Diagonalized Tube
• • • • •
•
•
•
•
• • • • ••
Type IV
Innovations
Innovations
• • •
• • •
• • •
• • •
• • •
• • •
• • •
• • •
• • •
10
Bundled Framed Tube
20
•• •• ••
•• • •• • ••
Semi-Rigid
Frame
30
Rigid Frame
40
•• • •• • ••
•• •• ••
50
Exterior Framed Tube
Frame with Shear Truss
60
• • •• • ••
(CTBUH, 1980)
•• • •• • ••
70
90
Shear Frames
Interacting Systems
Partial Tubular Systems
Tubular Systems
End Channel and Middle I
Framed Tubes
80
Type I
Type II
Type III
Type IV
End Channel Framed Tube with
Interior Shear Trusses
100
# of Floors
Frame with Shear band and
Outrigger Trusses
110
Conclusion
Conclusion
Shear Frame System
•
•
•
•
Resists lateral deformation by joint rotation
Requires high bending stiffness of columns and beams
Rigid joints are essential for stability
Not effective for heights over 30 stories
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
Braced Frame System
•
•
•
Lateral forces are resisted by axial actions of bracing and
columns
Steel bracing members or filled-in bays
More efficient than a rigid frame
Cantilever
Introduction
Introduction
Loads
Loads
Shear
Evolution
Evolution
Evolution
Evolution
Combined
Innovations
Innovations
Conclusion
Conclusion
Core Structure System
•
•
•
•
Lateral and gravity
loads supported by
central core
Eliminates columns
and bracing elements
Core is inefficient
because it is not deep
in respect to bending
Moment supported
floors are inefficient
Individually
cantilevered
floors
Cantilever
supports
Group
cantilevered
floors
Core
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
Outrigger Braced Structure System
•
•
•
1- or 2-story deep
truss connects core
to perimeter
columns
Outriggers
Increases the
bending rigidity
Dependent of rigid
core for shear
resistance
Braced
core
Tension
Compression
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
Tubular System
•
•
•
•
•
Majority of structural elements around the perimeter
Sides normal to lateral load resist bending
Sides parallel to lateral load resist shear
Minimize number of interior columns
Closely spaced exterior columns
Increased stress at corners
created by shear lag effect
Closely spaced columns
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
Hybrid Systems
• Combine advantages of different structural and material systems
• Composite material system
• Concrete super columns
• Steel encased concrete columns
• Composite floor system
• Steel truss and outrigger systems
• High strength concrete super columns reduce deflections and weight
• Steel encased HS concrete combines
• easy erectability of steel,
• axial load capacity of HS concrete,
• efficient confinement and reinforcement.
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
High-Efficiency Mega-Braced Frame System
Mega braces
•
•
•
•
Very large columns and
bracing
Small number of
columns
Bracing extends over
multiple floors
Stiff transfer floors allow
for internal flexiblity
Transfer zones
Mega columns
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
Evolution of Materials
• High performance concrete (HPC)
• High performance steel (HPS)
• Composite construction
Composite
33%
Steel
42%
Concrete
25%
Introduction
Introduction
Number of Buildings
Material systems of the tallest 200 Buildings
20
18
16
14
12
10
8
6
4
2
0
1930
1940
1950
1960
1970
1980
1990 2000*
Decade
Loads
Loads
Evolution
Evolution
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
Innovations
• Vulnerability and risk assessment
• Performance based design
• Materials
• Structural control
• Egress strategies
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Innovations
Innovations
Conclusion
Conclusion
Vulnerability and Risk Assessment
• Probabilistic risk assessment (PRA) and decision making have
been effectively used in
• nuclear engineering,
• manufacturing,
• seismic loss estimation etc.
• Probabilistic, nonlinear, and coupled evaluation of building
vulnerability is needed for identified hazards.
Hazard
identification,
prioritization and
evaluation
Risk assessment &
Loss estimation
Vulnerability
analysis
Introduction
Introduction
Loads
Loads
Decision &
Implementation
Optimum mitigation
strategy
Evolution
Evolution
Innovations
Innovations
Innovations
Innovations
Conclusion
Conclusion
Risk Assessment and Performance Based Design
Hazard Analysis
Amplification
Seismic
source
ation
Attenu
SPECTRAL ACCELERATION
Vulnerability Analysis
STRONGER CONSTRUCTION
WEAKER CONSTRUCTION
MINOR
SHAKING
MAJOR
SHAKING
MODERATE
SHAKING
SPECTRAL DISPLACEMENT
Structural model
Introduction
Introduction
Loads
Loads
NONE
SLIGHT
Evolution
Evolution
MODERATE EXTENSIVE COLLAPSE
Innovations
Innovations
Innovations
Innovations
Conclusion
Conclusion
Design for Fire
• Old: Prescriptive-Based Design
– Design based on fire rating of
materials used
– Fire rating of material from tables
– Compliance with a code specified
value
• New: Performance-Based Design
– Evaluate the strength and stiffness for a particular
design fire
– Coupled stress-thermal analysis
– Specialized design for fire effects
– Use of fire retardant materials, advanced coatings
and ceramics
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Innovations
Innovations
Conclusion
Conclusion
Performance Evaluation Under Fire
Coupled structural/fire analysis
Structural Model
Geometry
Elastic/strength
properties
Thermal
properties
Onset of fire
Time: 20 min
Demand
Structural loads
Fire modeling
Time: 35 min
Thermal analysis
Stress analysis
Time: 45 min
Weakest link
Deformations, damage, collapse
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Innovations
Innovations
Conclusion
Conclusion
Design for Impact Loading
Engineering problems related to impact loads:
•
•
•
•
•
Modeling of impact
Assessment of impact damage
Evaluation of structural safety after impact
Modeling of potential fire after impact
Coupled evaluation of structural integrity and collapse
potential
(FEMA 403)
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Innovations
Innovations
Conclusion
Conclusion
Impact Modeling
Floor
V
Core area
V
Floor
Boeing 767-200
Boeing 767-200
Exterior
columns
Core
columns
Boeing 767-200
Max. takeoff weight: 395,000 lb (180 ton)
Max. fuel capacity: 24,000 gal (91,000 liter)
Cruise speed: 530 mph (237 m/s)
Total kinetic energy
Velocity
V ≈ 220 m/s
Fuselage cutting force
Ek = 12 MV 2 = 3460 MJ
Pcutting ≈ 3.0 MN
MIT Impact and Crashworthiness Laboratory
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Innovations
Innovations
Conclusion
Conclusion
Energy Dissipation During Impact
The initial kinetic energy of the plane is dissipated
through
• Permanent plastic deformation (crushing)
Estimated distribution of
energy dissipation
• Generated Heat
• Fracture and fragmentation
Core
columns
28%
(creating new surfaces)
• Friction
• Residual velocity
• Elastic vibrations
Floor
structure
53%
May be used as
a design tool
Exterior columns
3%
Aircraft
25%
MIT Impact and Crashworthiness Laboratory
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Innovations
Innovations
Conclusion
Conclusion
Design for Blast Loading
Sequence of damage due to a
blast outside the building
Incident pressure waveform
(FEMA 427)
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Innovations
Innovations
Conclusion
Conclusion
Redundancy and Progressive Failure
REDUNDANCY: Presence of alternate load paths
PROGRESSIVE FAILURE: Successive failure of critical elements
• Redundancy is essential for structural safety and protection
• Ductile structural elements and details
• Design for load reversals
• Avoid shear failures
Structural behavior
Introduction
Introduction
Low redundancy
Loads
Loads
Evolution
Evolution
High redundancy
Innovations
Innovations
Innovations
Innovations
Conclusion
Conclusion
Redundancy and Progressive Failure
Redundancy in column system
System
Redundancy
(Global frame)
FEMA
403
Local Redundancy
(Local joints)
Redundancy in floor system
Improved
local
redundancy
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Innovations
Innovations
Conclusion
Conclusion
Design Against Progressive Failure
High-capacity column-beam
connections
Catenary action of cables
Cables in the floor
Catenary action
Before removal
of the column
After removal
of the column
(Astaneh-Asl, 2003)
Other possible design actions
• Transfer trusses at upper floors allowing
columns to hang
• Strong moment connections for cantilever
action of floor frames
• Perimeter frames with sufficient capacity
to span multi-bays
• Mega-brace systems capable of resisting
partial collapse
Introduction
Introduction
Loads
Loads
Evolution
Evolution
(Houghton and Karns)
Innovations
Innovations
Innovations
Innovations
Conclusion
Conclusion
Materials Development
• High performance concrete and steel enable efficient and
innovative design
• FRP composites may be effective in combination with
conventional materials
Relative MOE or Comp. Strength
• Fiber reinforced concrete shows promise in fire protection
Effect of Heat on Reinforced Concrete
(2 hours of exposure to 1000 C fire)
1
Compressive
Strength
0.8
0.6
0.4
Modulus of
Elasticity
0.2
0
0
200
400
600
800
Temperature (C)
Introduction
Introduction
Loads
Loads
1000
Ordinary RC
Evolution
Evolution
Innovations
Innovations
Innovations
Innovations
Riber RC
Conclusion
Conclusion
Structural Control
•
•
Lateral motion problems can be resolved through various
types of damping systems
Controls systems can be implemented in initial design or as a
retrofit
Passive dampers are commonly used in new tall buildings
•
Viscous Dampers
– Piston forcing fluid through an orifice
– Compact and easily installed
•
Hysteretic Dampers
– Dissipates energy by cyclic yielding in
tensions and compression
– Easy to install, but may need to be
replaced after major event
•
Tuned Mass Dampers (TMD)
– Translation TMD
– Pendulum TMD
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Innovations
Innovations
Conclusion
Conclusion
Structural Control Systems
Diagonal brace with viscous
or viscoelastic damper
Chevron brace with
viscous dampers
Pall friction damper
Tuned liquid column damper
damper spring
actuator
Tuned mass damper
Active mass damper
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Chevron brace with
viscoelastic damper
Tuned liquid damper
Hybrid mass damper
Innovations
Innovations
Innovations
Innovations
Conclusion
Conclusion
Passive Structural Control
John Hancock Building, Boston
Tuned Mass Dampers
cd
p
kd
md
u + ud
u
m
c
k
Governing equations of motion:
Building
p
&&
&
(1+ m)u + 2ξωu + ω u = − mu&&d
m
2
Damper
md
m=
m
u&&d + 2ξdωd u&d + ωd2ud = −u&&
Introduction
Introduction
Loads
Loads
ki
ω =
mi
2
i
ci = 2ξiwi mi
Evolution
Evolution
Innovations
Innovations
Innovations
Innovations
Conclusion
Conclusion
Active Structural Control
Hybrid Mass Dampers
cd
p
kd
u + ud
Nishikicho Building, Tokyo
(Connor, 2003)
u +ud + ua
u
m
c
k
Governing equation of motion for the AMD
u +ud + ua
ka
F
Introduction
Introduction
ma
u&&a + ωa2ua = −(u&& + u&&d ) +
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Innovations
Innovations
F
ma
Conclusion
Conclusion
Health Monitoring
Vibration techniques can be used to determine the vibration
characteristics of high-rise buildings
Advantages
• Rapid
• Can be used for periodic or
continuous monitoring
• Economically feasible
• Provides a preliminary
assessment of the building
stiffness
• Leads to more accurate seismic
demand prediction
Accelerometer(s)
Data acquisition
unit
Ambient vibrations
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Innovations
Innovations
Conclusion
Conclusion
Emergency Egress Strategies
•
Elevated passages to neighboring buildings
•
Refuge floors/rooms with fire escape elevators
•
Perimeter wall rescue vehicles
•
Fire resistant escape chutes
•
Flying rescue platforms
•
Individual fire resistant parachutes
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Innovations
Innovations
Conclusion
Conclusion
Conclusions
• Highrise buildings enjoy rapid evolution and new
innovations
• Efficient composite hybrid structural systems for
super-tall buildings
• Use of composite material systems
• Improved analysis and design tools for better
fire, impact, blast resistance
• Redundancy against progressive failure
• Effective egress strategies
• Use of passive and active control systems
• Implementation of health and long-term
performance monitoring
Introduction
Introduction
Loads
Loads
Evolution
Evolution
Innovations
Innovations
Conclusion
Conclusion
Conclusion
Conclusion