Structural Engineering Solutions for Architecture Challenges by Dr. Naveed

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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

Developing 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

“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
LoadingSeverity
Resta
urant
Resta
urant
Resta
urant
Hazard
Vulnerability
Consequences

Structural Response Can be Linked to Other Decisions
14
Restaurant Restaurant
Restaurant
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 Design
Client

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

CONTROLLING 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

NEWER 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 Engineers
By Computers and Structures Inc. USA
A 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

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Thank you

Structural Engineering Solutions for Architecture Challenges by Dr. Naveed

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