naveed anwar, phd progression of structural design approaches

Naveed Anwar, AIT Solutions

Progression of Structural Design Approaches Naveed 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 solutionsdevelopment

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

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Milestones

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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

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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

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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

http://www.prb.org/


• 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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Japan, 4000m Sky Mile Tower, 1700 m JapanDubai City Tower, 2400 m One Dubai Tower, 1008 m


Source: CTBU Report, 2015


The Twisting Turning Towers Trend

Source: CTBU Report, 2015


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Needs Innovations in Structural Design Approaches

Naveed Anwar, AIT Solutions22

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 orHow 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 !

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Win

d

Earthquake


Stability

01

Strength

02

Deformation

03

Drift

04

Ductility

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Energy Dissipation

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Motion Perception

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Spirit of the code isto 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 Baltimorefirst building code in 1859.

In 1904, a Handbook of the Baltimore

City

In 1908 , a formal

building code was

drafted and adopted.

The International

Building Code (IBC) by (ICC).

European Union,

the Eurocodes.


UBC, IBC

ACI, PCI, CRSI, ASCE, AISI,

AASHTO

British, CP and BS

Euro-codesChina, 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

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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

ügv

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 inelasticallyunder 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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Intuitive Design

Code Based Design

Performance Based Design

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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

Lo

adin

g S

ever

ity

Resta

urant

Resta

urant

Resta

uran

t

Ha

zard

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


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Wind

Earthquake


Is this acceptable?Even though it satisfies CBD and PBD


Intuitive Design

Code Based Design


Consequence and Risk Based Design

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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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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


Consequences and Risk Based Design

Resilience Based Design

Wind

Earthquake


Green Buildings Resilient Buildings

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Main authors : ArupSupported by USRC and many others


Extreme Events should be handled Consistently

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Earthquakes, Wind, Blast, Progressive Collapse, Impact


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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

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Economic Loses

Loss of Community and Culture

Loss of Quality of

Life

Go Beyond Life Safety


Restaurant Restaurant

Resta

uran

t

Operational (O) Immediate Occupancy (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 Minimize ConsequencesHighest 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 Structural Analysis and Design

Integrated Analysis, Design and Drafting of Building Systems

Integrated Design of Flat Slabs, Foundation Mats and Spread Footings

Nonlinear Analysis and Performance Assessment for 3D Structures

Design of Simple and Complex Reinforced Concrete Columns


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Thank you

naveed anwar, phd progression of structural design approaches

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