Progression of Structural Design Approaches by Dr. Naveed Anwar

Naveed Anwar, AIT Solutions
Progression of Structural Design ApproachesNaveed Anwar, PhD

Naveed Anwar, AIT Solutions 2
Professional Education Integrated Solutions
ResearchAcademics The Asian Institute of Technology (AIT) promotes
technological advancement and sustainable
development in the Asia-Pacific region through its four
key strengths
“To contribute towards the technological
development of the region through deeper and
expanded engagement and delivery of AIT’s
research, knowledge and expertise”

Focus on solutions
development
Strengthen and deepen
work IP protection and
as incubation of ideas
Build on the strengths,
vision & mission, and
resources of AIT
Enable greater
engagement of AIT to
be more beneficial to
the institute as well as to
society as a whole
3

Milestones
4
2010
2011
2012
20152013
2014
AIT Consulting AIT Solutions
2016
ACECOMS joined
AITC
Increase in tall buildings,
bridges, and special structures
projects
Organized the first-ever
AIT Technology event
Habitech and AITS jointly
work together
Repositioning
& Rebranding

Solutions
5
Disaster Risk Reduction and
Management
Affordable Housing
Resilient Structures Skill and Capability
Enhancement
Project Reviews
IT and Software
Environment
Knowledge Sharing

Habitech Center – Devilment of Building Technologies
Sustainable and
cost-effective
housing
Social
infrastructure
buildings for
communities
Eco-friendly
building materials,
technologies that
not only sustain
life but also
conserves our
environment
AIT, through Habitech Center, has been instrumental in contributing
significantly in developing

Habitech Building System

Why this Seminar?
And why are these topics important

Demand and Complexity is Increasing
for the Built Environment

(www.un.org)

Population Growth is in Developing World
12
Source: www.prb.org, volume no. 66, July, 2011.
Less Developed
Countries will
need more Low
Cost Housing
and
infrastructure
for nearly
2 Billon more
people

• Definition used by McKinsey Report
• Household (not individual)
• 30% of income for housing
• Household having 80% of median income should
be able to afford the housing
• This needs to be tackled worldwide!
50 %
Household
Having
More
50%
Household
Having Less
Median Income
80% Median Income

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14

Japan, 4000m Sky MileTower, 1700 m JapanDubai CityTower, 2400 m One DubaiTower,
1008 m

Source: CTBU Report, 2015

TheTwistingTurningTowersTrend
Source: CTBU Report, 2015

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Needs Innovations in Structural
Design Approaches

22
Is my Structure safe?
(What level of Richter earthquake my structure sustain?
Or what tornado level can it withstand,
or is it safe for explosions or
How long can it withstand the fire?)

How long do we have
before the building will
collapse in this fire?
- Asks the Fire Chief from the structural
engineer
1974

https://www.youtube.com/watch?v=FagbC09BO2o

Ancient masterpieces were built before the modern approaches
Master builders had freedom to dream and to realize them

Intuitive
Design
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What a Structural Engineer said !
Hardy Cross, 1885-1959

Intuitive
Design
Code
Based
Design
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-

Main
Challenges !
29
Wind
Earthquake

Stability
01
Strength
02
Deformation
03
Drift
04
Ductility
05
Energy
Dissipation
06
Motion
Perception
07
30

•
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Spirit of the code is
to help ensure Public Safety and
provide formal/legal basis for design
decisions
Compliance to
letter of the code is
indented to meet the spirit

“Rebuilding
of London
Act” after the
“Great Fire of
London” in
1666 AD.
In 1680 AD,
“The Laws of
the
Indies” Spani
sh Crown
London
Building Act of
1844.
In USA, the
City
of Baltimore
first building
code in 1859.
In 1904, a
Handbook of
the Baltimore
City
In 1908 , a
formal
building
code was
drafted and
adopted.
The Internat
ional
Building
Code (IBC)
by (ICC).
European
Union,
the Eurocodes.

UBC, IBC
ACI, PCI, CRSI,
ASCE, AISI,
AASHTO
British, CP and
BS
Euro-codes
China, USSR,
Japan

• Traditional codes govern design of general, normal buildings
Over 95% buildings are covered, which are less than about 50 m
• Not specifically developed for tall buildings > 50 m tall
• Prescriptive in nature, no explicit check on outcome
• Permit a limited number of structural systems
• Do not include framing systems appropriate for high-rise
• Based on elastic methods of analysis
• Enforce uniform detailing rules on all members
• Enforce unreasonable demand distribution rules
• Do not take advantage of recent computing tools

Traditional
Design
approach for
Wind and
Earthquake is
different and is
often
in-consistent
and opposing
35

Seismic LoadWind Load
Depend on
•focus of earthquake
•Shaking intesity
•ground conditions
•Mass and stiffness
distribution
Depend on
• Wind speed
• terrain
• topography of the location
• Force increases with height
• Geometry and exposed area
m
üg
v
A
 Excitation is an applied displacement
at the base
 force will be distributed along interior
and exterior lateral load resisting
elements
 Excitation is an applied pressure or
force on the facade
 force will act mainly on exterior
frames then transferred to floor
diaphragms

 For most buildings, dynamic wind response may
be neglected
 Gust factor approach  predict dynamic
response of buildings with reasonable accuracy
 Structures are designed to respond elastically
under factored loads
 Structures are designed to respond inelastically
under factored loads
 it is not economically feasible to design structures
to respond elastically to earthquake ground
motion
Design for Seismic EffectsDesign for Wind Load

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38

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39

Intuitive
Design
Code Based
Design
Performance
Based
Design
-
-
Earthquake
Wind

• Lack of explicit performance in design codes is
primary motivation for performance based
design
• Performance based methods require the
designer to assess how a building is likely
perform extreme events and their correct
application will help to identify unsafe designs.
• Enables arbitrary restrictions to be lifted and
provides scope for the development of
innovative, safer and more cost-effective
solutions

Based on FEMA 451 B

Structural Displacement
LoadingSeverity
Resta
urant
Resta
urant
Resta
urant
Hazard
Vulnerability
Consequences

Performance based design investigates at least two performance objectives explicitly
Service-level
Assessment
Negligible damage with
frequent hazards
(Earthquake having a return
period of about 50)
Collapse-level
Assessment
Collapse prevention under
extreme hazards
(the largest earthquake with a
return period of 2500 years)
Code’s arbitrary
“Design Level”

Intuitive
Design
Code Based
Design
Performance
Based
Design
-
Wind
Earthquake

Is this acceptable?
Even though it satisfies CBD and PBD

Intuitive
Design
Code Based
Design
Performance
Based Design
Consequence
and Risk
Based Design
-
Wind
Earthquake

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Code based was implicit, with
not confirmation of response
PBD is explicit, can help to
confirm the response and
performance level

• For public and society, the performance criteria still does reduce the effects of the
events, but it can reduce the risk level
• The non structural damage is not acceptable in modern buildings
• The disruption and loss goes much beyond the building
• Insurance companies want to have greater reliability of assessment of risk and
damages

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50
The trigger of an event is not important,
the consequences of an event are

Safety Studies
(Probability and
Consequence Analysis)
Risk
Quantification
Safety Critical
Element
Design
Accidental
Load
Structure
Design

Intuitive
Design
Code Based
Design
Performance
Based Design
Consequence
s and Risk
Based Design
Resilience
Based
Design
Wind
Earthquake

Green Buildings Resilient Buildings
53
Main authors : Arup
Supported by USRC and many others

Extreme Events
should be
handled
Consistently
54
Earthquakes, Wind, Blast,
Progressive Collapse, Impact

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55

RESILIENCE
Economic
Social
Organizational
Technical
Resourcefulness
Redundancy
Rapiditty
Robustness
Lower
Consequences
Faster
Recovery
More Reliability
4 Dimensions of
Resilience
4 Properties of
Resilience
3 Results of Resilience
56

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57
Economic Loses
Loss of
Community
and Culture
Loss of
Quality of
Life
Go Beyond Life Safety

Restaurant Restaurant
Restaurant
Operational (O) ImmediateOccupancy (IO) Life Safety (LS) Collapse Prevention (CP)
0 % Damage or Loss 99 %
Ref: FEMA 451 B
CasualtiesLowest Highest
Rehab Cost to Restore after eventLowest Highest
Retrofit Cost to MinimizeConsequencesHighest Lowest
Downtime for RehabLowest Highest
Impact on Sustainability of CommunityLowest Highets

ARUP

Tools: How to design efficiently?

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• Initially, computers were used to
program the procedure we had
• Now, we develop procedures that
are suited for computing

Integrated 3D Bridge Design Software
Integrated Software for StructuralAnalysis and Design
IntegratedAnalysis, Design and Drafting of BuildingSystems
Integrated Design of Flat Slabs, Foundation Mats and Spread Footings
NonlinearAnalysis and PerformanceAssessment for 3D Structures
Design of Simple andComplex ReinforcedConcreteColumns

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65

Progression of Structural Design Approaches by Dr. Naveed Anwar

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