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Naveed Anwar, PhD

Innovative Structural Engineering – Naveed Anwar, AIT (IAPEX, Lahore March 2015)

• Architectural Design and Structural Engineering

– Bigger, taller, complex forms, but

Lighter, smaller, thinner structural elements

– High performance, but Lower cost

• Architects and Structural Engineers

– Apparent lack of innovativeness

– Difficulties in collaborative working

The Challenges

2

Click to edit Master title styleDeveloping a Structural Solution

The Conceptualizing Phase


Advise to my fellow Engineers

1. Design is a team effort, and Architect is the lead

2. Everything is possible, don’t say no!

– but it needs innovation, knowledge, skills, tools and,

– of course resources

3. - - -


• Design a Rectangular

Water Tank of

3mx4mx2m

– Most engineers will

readily calculate the

wall thickness and

required rebars and

the cost

• Design the most

efficient and cost

effective water tank to

hold 24 cuM of water

– Many designs are

possible

– Most engineers will

not know how to

start?

Conceptualizing a Solution

5


• Explicit learning from

experience

• Combination of

Rational and Heuristic

thinking

• Encapsulating natural

thinking process into

formal decision systems

Decisions Support Systems


System Design

• Rich Pictures

• Analytical Hierarchy Process (AHP)

• Artificial Neural Networks (ANN)

• Genetic Algorithms (GA)

• Expert Systems (ES)

• Fuzzy Logic

• Deep Thinking

• Big Data and Data Mining

Innovative Structural Engineering – Naveed Anwar, AIT (IAPEX, Lahore March 2015) 8

Rich Picture for Choosing Structural System


ANN for Tall Buildings

9

Architectural

Layout

Preliminary

Sizing Structural

Response

• Number of story

• Length, Width,

Height

• Grid spacing

• ..

• Column size

• Shear wall size

• Rebar quantities

• Natural period

• Drift ratio

• Base shear

To make design preliminary decisions without explicit calculations

Click to edit Master title style“IS MY STRUCTURE SAFE?”:CBD, PBD, RBD, CBE


• Traditional approach

– “Not sure, but I know I followed the code (ACI/BS..)”

• New approach

– First, define “Safe”

• Safe against what, how safe …

– Second, use explicit evaluation of safety

• Get freedom from the “code”

• Use advanced technologies

– Get clear answer about safety and performance

Is my structure safe ?

11


• Code Based Design (CBD)

• Performance Based Design (PBD)

• Risk Based Design (RBD)

• Consequence Based Engineering (CBE)

Design Approaches

12


Structural Response Can be Linked to Other Decisions

13

Structural Displacement

Load

ing

Sev

erity

Resta

urant

Resta

urant

Resta

urant

Ha

zard

Vulnerability

Consequences


Structural Response Can be Linked to Other Decisions

14

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


How to work with PBD

15

Architect

Structural Engineer

PBD Specialist

PBD Reviewer

Site Specific Consultant

Performance Based DesignClient


Cost and Performance

16

PCC

Cost Effective

Design

Can be done PC

General Belief

Easy to do !

PC

Highly Innovative

Design

Hard to do!PC

High

Performance

Design

Can be done


• To solve the problem, solve the cause of the

problem

• Performance is a Demand and Capacity balance

– Traditional way: Increase capacity to meet demand

– Alternate way: Reduce demand to match capacity

Alternate Approach

17


AIT and PBD

Just in last 5

years,

AIT has become a

Regional leader in

Performance

Based Design of

Tall Buildings

55 million Sft

Click to edit Master title styleCONTROLLING FORCES AND

MOVEMENTS IN STRUCTURES:BRB, dampers, isolators, hinges, fuses


Forces

• Separate the forces into

– Directly applied, externally applied

– Movement based

• Movement based forces can be controlled

– Mass based

– Temperature based

– Settlement based

– Internal deformation based


• Determining Movements

– Modal Analysis

– Static Analysis

– Time History Analysis

– Wind Tunnel tests

• Controlling Movements

– Stiffness and mass distribution

– Installing Dampers

• Mechanical, Mass Tuned, Liquid, Viscous

– Base Isolators

Movements

21


• Natural vibration is the key to controlling most

movement based forces

• Natural Period and Mode Shapes are the pulse of

the structure

• Understanding modal response is vital for engineers

and architects

Natural Vibration

22


Buddha Statue, Bangkok


http://www.bridgestone.com/products/diversified/antiseismic_rubber/method.html

Mechanical Isolators and Dampers


Tuned Mass Dampers

Tuned Dampers


BRB – Braces that Don’t Buckle

27

Click to edit Master title stylePREVENTING THE DOMINO EFFECT:Progressive collapse analysis


Progressive Collapse

• A new and major concern for structural safety

• Structure should not collapse completely if one or

two elements are “destroyed”

• Backup systems, alternate load paths, additional

redundancy

Click to edit Master title styleROME WAS NOT BUILT IN A DAY:The construction Sequence analysis


• Structure is normally analysed as if it is already fully

built

– Make the model, and apply loads

• Step-wise construction sequence analysis is

essential for better and correct understating and

design

– Make the model, as it is built

– Apply loads as they are applied

– Consider temporary shoring etc

– Consider in-construction corrections

– Consider the aging effects

Analysing for Construction Sequence


Without and With Construction Sequence

33

Click to edit Master title styleTOGETHER OR SEPARATE:Free, flexible, or rigid connections


Connections

• Connecting two buildings or parts of structure in the

right way can lead to innovative solutions

– Rigidly connected

– Fully free to move

– Flexible connections

– Elasto-Plastic Connections

– Fuses

Click to edit Master title styleNEWER AND BETTER TOOLS AND TOYS:Advanced modeling and analysis Software


Software

• Modelling capability

– Object based modelling

– BIM links between CAD and FEA and building lifecycle

• Analysis Capability

– From simple linear-elastic analysis

– To highly complex nonlinear-inelastic-dynamic analysis


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

Tools of the Trade for Structural EngineersBy Computers and Structures Inc. USAA company created and run by Ashraf Habibullah


Detailed Seismic Analysis

Click to edit Master title styleSome Interesting Solutions


Gramercy Residence, Manila


Park Terraces, Manila


Pruksa Precast, Bangkok


Aqua Towers, Manila


Iconic Bridge, Manila


Robbie House, Manila


Precast Houses


Temple Dome, Bangkok


Fixing the Old to Serve Again

50


MOFAT, Brunei


Ireo, India


Shanta Glass, Dhaka


Lang Suan, Bangkok


Central Embassy, Bangkok


Floor 1 to 9

Floor 9 to 16

Floor 16 to 30


Two e Com, Manila


Star View, Bangkok


We like challenges!

Thank you

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