High Rise Building

Massachusetts Institute of TechnologyCambridge, MA, USA

High-Rise Buildings: Evolution and Innovations

Keynote LectureCIB2004 World Building Congress

Toronto, Ontario CANADAMay 2-7, 2004

Dr. Oral BuyukozturkProfessor of Civil and Environmental Engineering

Oguz GunesPh.D. Candidate

© 2004 IST Group. All rights reserved

IntroductionIntroduction LoadsLoads EvolutionEvolution InnovationsInnovations ConclusionConclusion© 2004 IST Group

OUTLINE

• INTRODUCTION

• LOADS

• EVOLUTION

• INNOVATIONS

• 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

IntroductionIntroduction


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

IntroductionIntroduction LoadsLoads EvolutionEvolution InnovationsInnovations ConclusionConclusion


(Tables source: Emporis Corporation April 2004)

Geographical Distribution of High-Rise Buildings



Economy vs. Demand for High-Rise BuildingsEconomic growth and resulting demand for office space is a good indication of demand for high-rise buildings

U.S. Asking Office Rents, Class A$ Per Sq. Ft. Per Year Full Service

$20

$30

$40

$50

Jan-98Jan-99Jan-00Jan-01Jan-02Jan-03Jan-04

CBD Suburban

U.S. Office Vacancy Rates

5.0%7.0%9.0%

11.0%13.0%15.0%17.0%19.0%

86 88 90 92 94 96 98 00 02 04

U.S. Office Supply vs. DemandSq. Ft. in Millions

-100-50

050

100150

86 88 90 92 94 96 98 00 02 04

Completed Absorbed


U.S. Gross Domestic Product

-2%0%2%4%6%8%

10%

2001 2002 2003 2004

(Grubb & Ellis Company, 2004)


Structural Loads

• Gravity loads – Dead loads – Live loads– Snow loads

• Lateral loads– Wind loads– Seismic loads

• Special load cases– Impact loads– Blast loads

Earthquake Load

Snow Load

Wind Load

Dead Loads

Live Loads

Blast Load

ImpactLoad



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


Wind Loads

Plan view

Wind

zQ hQzQ

hQ

hQ hQ

2zQ KV I=

z

h z z HQ Q

==

H


(Schueller, 1977)

(Taranath, 1998)


Seismic Loads

Spe

ctra

l res

pons

e ac

cele

ratio

n (g

)

Period (sec)

0 2 4 6 8

Response with increasing damping

Decreasing V/W

sV C W= ×

V

W



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)


Evolution of Structural Systems

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


A clear classification of high-rise buildings with respect to their structural system is difficult

A rough classification can be made with respect to effectivenessin resisting lateral loads


Evolution of Structural Systems

10

2030

40

5060

70

80

90

100

110

Type I Shear FramesType II Interacting SystemsType III Partial Tubular SystemsType IV Tubular Systems

• • • ••

••

••

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Type I

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••

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Type II Type III

•• • • •• ••

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• •• •

Type IV

•• • • •• •

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•

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Sem

i-Rig

idFr

ame

Rig

id F

ram

e

Fram

e w

ith S

hear

Tru

ss

Fram

e w

ith S

hear

ban

d an

d O

utrig

ger T

russ

es

End

Cha

nnel

Fra

med

Tub

e w

ith

Inte

rior S

hear

Tru

sses

End

Cha

nnel

and

Mid

dle

IFr

amed

Tub

es

Exte

rior F

ram

ed T

ube

Bun

dled

Fra

med

Tub

e

Exte

rior D

iago

naliz

edTu

be

# of Floors

EvolutionEvolution

(CTBUH, 1980)


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



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 Shear Combined


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


Cantilever supports

Individually cantilevered

floors

Core

Group cantilevered

floors


Outrigger Braced Structure System

• 1- or 2-story deep truss connects core to perimeter columns

• Increases the bending rigidity

• Dependent of rigid core for shear resistance


Outriggers Braced core

Tension

Compression


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


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.

EvolutionEvolution


High-Efficiency Mega-Braced Frame System

• Very large columns and bracing

• Small number of columns

• Bracing extends over multiple floors

• Stiff transfer floors allow for internal flexiblity


Mega braces

Transfer zones

Mega columns


Evolution of Materials

• High performance concrete (HPC)• High performance steel (HPS)• Composite construction

Steel42%

Concrete25%

Composite33%

02468

101214161820

1930 1940 1950 1960 1970 1980 1990 2000*

Decade

Num

ber o

f Bui

ldin

gs

Material systems of the tallest 200 Buildings



Innovations

• Vulnerability and risk assessment

• Performance based design

• Materials

• Structural control

• Egress strategies

InnovationsInnovations


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

Vulnerability analysis

Risk assessment & Loss estimation

Optimum mitigation strategy

Decision & Implementation



MINORSHAKING

MODERATESHAKING

MAJORSHAKING

WEAKER CONSTRUCTION

STRONGER CONSTRUCTION

SPECTRAL DISPLACEMENT

SPEC

TRA

L A

CC

ELER

ATI

ON

NONE SLIGHT MODERATE EXTENSIVE COLLAPSE

Vulnerability Analysis

Structural model

Risk Assessment and Performance Based Design


Attenuation

Amplification

Seismic source

Hazard Analysis


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



Performance Evaluation Under Fire

Coupled structural/fire analysis

Structural loads

Thermal analysis Stress analysis

Fire modeling

Deformations, damage, collapse

Elastic/strength properties

Thermalproperties

Structural Model Geometry

DemandTime: 20 min

Onset of fire

Time: 35 min

Time: 45 min

Weakest link



Design for Impact Loading

• 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


Engineering problems related to impact loads:

(FEMA 403)


Impact Modeling

220 m/sV ≈

212 3460 MJkE MV= = 3.0 MNcuttingP ≈

Velocity

Total kinetic energy Fuselage cutting force

MIT Impact and Crashworthiness Laboratory

Exteriorcolumns

Corecolumns

Boeing 767-200

Floor

Floor

Core area

Boeing 767-200

Boeing 767-200Max. takeoff weight: 395,000 lb (180 ton)Max. fuel capacity: 24,000 gal (91,000 liter)Cruise speed: 530 mph (237 m/s)

VV



The initial kinetic energy of the plane is dissipated through

• Permanent plastic deformation (crushing)• Generated Heat• Fracture and fragmentation

(creating new surfaces)• Friction• Residual velocity• Elastic vibrations

Energy Dissipation During Impact

Core columns

28%

Aircraft25%

Exterior columns3%

Floorstructure

53%

Estimated distribution of energy dissipation

May be used asa design tool

MIT Impact and Crashworthiness Laboratory



Design for Blast LoadingSequence of damage due to a

blast outside the buildingIncident pressure waveform

(FEMA 427)



Redundancy and Progressive Failure

Structural behavior Low redundancy High redundancy

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



Redundancy and Progressive FailureRedundancy in column system

Redundancy in floor system

System Redundancy(Global frame)

Local Redundancy(Local joints)

FEMA403


Improved local

redundancy


Design Against Progressive Failure

• 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

Other possible design actions

High-capacity column-beam connections

(Houghton and Karns)

Catenary action of cablesCables in the floor

Before removal of the column

After removal of the column

Catenary action

(Astaneh-Asl, 2003)



Materials Development

• High performance concrete and steel enable efficient and innovative design

• FRP composites may be effective in combination with conventional materials

• Fiber reinforced concrete shows promise in fire protection

0

0.2

0.4

0.6

0.8

1

0 200 400 600 800 1000

Temperature (C)

Rel

ativ

e M

OE

or C

omp.

Str

engt

h

Modulus of Elasticity

0

0.2

0.4

0.6

0.8

1

0 200 400 600 800 1000

CompressiveStrength

Effect of Heat on Reinforced Concrete(2 hours of exposure to 1000 C fire)

Ordinary RC Riber RC



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

• 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

Passive dampers are commonly used in new tall buildings



Pall friction damper

Active mass damperTuned mass damper

Tuned liquid column damper Tuned liquid damper

Diagonal brace with viscous or viscoelastic damper

Chevron brace with viscous dampers

Chevron brace with viscoelastic damper

Hybrid mass damper

damper spring actuator

Structural Control Systems



Passive Structural Control

m

dc

c

dmdk

k

udu u+

Governing equations of motion:

dmmm

=2(1 ) 2 dpm u u u mum

ξω ω+ + + = −

22d d d d d du u u uξ ω ω+ + =−

Building

Damper

John Hancock Building, BostonTuned Mass Dampers

p

2i i i ic mξ= ω

2 ii

i

km

ω =



Active Structural Control

m

dc

c

dk

k

u

du u+

Governing equation of motion for the AMD

Hybrid Mass Dampers

p d au u u+ +

d au u u+ +

F amak

2 ( )a a a da

Fu u u um

ω+ =− + +

Nishikicho Building, Tokyo(Connor, 2003)



Health Monitoring

Ambient vibrations

Accelerometer(s)

Data acquisition unit

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



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



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

ConclusionConclusion

High Rise Building

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