International Conference on Sustainable Development in Civil Engineering, 23th - 25th November, 2017, Jamshoro

1. Trends and
Advancements for
Structural Performance
Naveed Anwar

2. The Towering Inferno (1974)
2
Structural Engineer advising the army and fire chief on strength and
safety of remining life structural members on site

3. 3 3
Ancient masterpieces were built through intuition and experience
Master builders had freedom to dream and to realize them

4. 4
Beginning of Structural
Engineering
• recognition of the loads,
• and fact that loads have an effect on members and
materials
• and that there is a resistance within materials to resist
the loads effects
• and that there is some relationship between them
1655-1705

5. 5
Increasing
Understanding

6. 6
Progression of Design Approaches

7. 7
Recognizing Performance as a
Goal to be Achieved

8. 8
Main Structural Performance Concerns
Stability and
integrity
01
Strength and
Servivbility
02
Deformation
03
Drift
04
Ductility
05
Energy
Dissipation
06
Motion
Perception
07

9. 9
Innovation
Performance
can not be
achieved in
Isolation

10. 10
From Prescription to
Performance

11. 11
Don’t tell them
how to do
Tell them what
is expected
• Make concrete
• 1:2:4, W/C =0.6, Slump=50mm, ….
• Deliver concrete
• 70 MPA, high durability, low shrink, ..

12. 12
A Move Towards Performance-based Approach
• Prescriptive Codes restrict
and discourage innovation Objective Requirements
Prescribed
Solution
Objective Requirements
Alternate
Solution
• Performance Based
approach encourages and
liberates innovation

13. 13
Prescriptive Codes – A Shelter and an Impediment
• Public:
• Is my structure safe ?
• Structural Engineer:
• Not sure, but I did follow the “Code”
As long as engineers follow the code, they can be
sheltered by its provisions

14. 14
PBD Approach
Owner
Will the building be safe?
Can I use the building
after the hazard?
How much will repair cost
in case of damage?
How long will it take to
repair?
Engineer
Free to choose solutions, but
ensure amount of yielding,
buckling, cracking, permanent
deformation, acceleration, that
structure, members and materials
experiences
Need a third party to ensure public safety
and realistic Performance
Guidelines
Peer Review

15. 15
Specify Performance Expectance for Hazard Levels
15
Acceptance Criteria for Maximum Considered Earthquake
(MCE)
Item Value
Peak transient drift
(TBI, Page 71) , (LATBSDC,
Page 40)
Maximum of mean values shall not
exceed 3%.
Maximum drift shall not exceed 4.5%.
Residual drift
(TBI, Page 71) , (LATBSDC,
Page 40)
Maximum of mean values shall not
exceed 1%.
Maximum drift shall not exceed 1.5%.
Coupling beam inelastic
rotation
≤ASCE 41-13 limits
Column Inelastic Rotation ≤ASCE 41-13 limits
Shear wall reinforcement axial
strain
≤0.05 in tension and ≤0.02 in
compression
Shear wall shear Remain elastic. (Check for 1.5 times
mean value)
Girder inelastic rotation ≤ASCE 41-13 limits
Girders shear Remain elastic.
Force
Structural
Displacement
Immediate
Occupancy
(IO)
Life
Safety
(LS)
Collapse
Prevention
(CP)

16. 16
100
200
300
meters
PBD of 100+ Tall Buildings
Gramercy
Residences
Stratford
Residences
Shang
Salcedo Place
Royalton
Tower
Discovery
Primea
One Shangri-la
Place (Tower
1&2)
Anchor
Grandsuites
Maven
Tower 1
Knightsbridge
Residences
Imperium
Tower
Park
Terraces
Tower
Garden
Tower
Shangri-la
at the
Fort
Trump
Tower

17. 17
Designing for different
Hazards in Consistent Manner

18. 18 18
▪ 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

19. Earthquake and Wind PBD are Compatible!
19
Site specific Seismic Hazard
Study
Site specific Climate
Analysis
Various Earthquake levels
SLE, DBE, MCE etc
Various Wind Return
period and Velocities
Hazard Response Spectrum Wind Force in Frequency
Domain
Ground Motion Time
History
Wind Tunnel Pressure in
Time Domain
Earthquake Wind

20. 20
A shift to Multi Hazard Approach

21. Extreme Hazzard Events
should be handled
Consistently
21
Earthquakes, Wind, Fire, Blast,
Progressive Collapse, Impact…

22. 22
Key Focus for Structural Engineers
• Sensing and monitoring of built structures
and calibration of models
• Validation of modeling approaches for
wind and earthquake
• Improved protection, design guidelines
from multiple hazards
• Application of PBD across all hazards

23. 23
Improvements in the
Tools of the Trade
Better analysis and design methods
and software

24. 24
Design Procedures and Software
• Initially, computers were used to
program the procedure we had
• Now, we develop procedures that
are suited for computing

25. 25
Analysis
Procedures
Non-Linear Response History Analysis (NLRHA)
Non-Linear Static Procedure (NSP)
Construction Sequence Analysis
Uncoupled Modal Response History Analysis
(UMRHA)—Chopra and Goel (2002)
Linear Response Spectrum Analysis (LRSA)
Linear Response History Analysis (LRHA)
NeedR

26. 26
Open-source
and
Collaborative
systems

27. 27
Popular Software for Structural Engineers
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

28. 28
Developing Calibrated Models
For materials, sections,
connections, members…

29. A Rational Approach for Developing New Systems
Calibration of with Finite Element Analysis
Full 3D Finite Element Modeling of Typical Structures
Evaluate the Performance Acceptance of Real Sites
Experimental Study and Details

30. Calibration Process
Test Model FE Model
Connection to test

31. 31 31

32. Localization for Site Specific Criteria
FoundationsResponse Spectrum

33. 33
Sensing and Monitoring
Structures
Real Structures as Labs

34. 34
Post Event Building Monitoring

35. 35
Possible Applications
• Calibration of models using natural
periods
• Comparison of Seismic Hazard
• Extraction of Vibration Characteristics
from Recorded Data
• Damage Assessment after the Event
• Detailed Performance-based Seismic
Evaluation

36. 36
Making Structures Smarter
In controlling hazards and
response

37. 37
Why we need
“Smart Structures”
• Excitation fluctuates so Demand fluctuates
• But Capacity is constant
• Therefore level of safety is not consistent
• Typically capacity is designed based on “Peak” demand
• What if peak demand never comes > Uneconomical
• What if demand exceeds estimated peak > Un-safe

38. 38
• Smart materials and memory alloys
• Energy Dissipating Systems
• Active or Passive Control Systems
• Health Monitoring Systems
• Data Acquisition System

39. 39
The Wonderful Buckling Restrained Braces - BRB

40. 40 40
Smart structures use smart devices and matersisl
to add some intelligence to adapt, react, adjust,
respond and handle multiple demands, and
levels as and when needed
Help to make the structures safer, specially for
earthquakes and strong winds

41. 41
Bringing in AI and IT
into Structural Design

42. 42
A Swing Towards the AI
• Rich Pictures
• Analytical Hierarchy Process (AHP)
• Artificial Neural Networks (ANN)
• Genetic Algorithms (GA)
• Expert Systems (ES)
• Machine Learning (ML)
• Fuzzy Logic
• Deep Thinking
• Big Data and Data Mining

43. 43
Using AI in Structural Design Process
Architectural
Design
Preliminary
Sizing
Structural
Modeling
Structural
Analysis
Code Based
Design
Performance
Based Design
43
Iterative, computationally intensive and time consuming

45. 45
CSI Apps for On-the go, Paperless Teaching/Learning
45
Faculty will create
activity and assign
students…
Student will work on the
activity and submit…
Faculty can view the results
of the submitted activities…

46. 46
A Sample Course

47. 47
A move towards Resilience
Recognizing that Purpose and impact
of Structures is More Important than
Structures

48. 48
Linking Performance to other Indicators
48
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

49. 49
Overall Nonstructural Damage under both SLE and MCE
4.7%
0.6% 0.2%
3.9%
23.17%
3.01%
0.84%
19.32%
0.0%
5.0%
10.0%
15.0%
20.0%
25.0%
Total damage Architectural damage Mechanical and electrical
damage
Building content damage
Percentageofdamage
Service level earthquake Maximum considered earthquake

50. 50Source: Arup, Supported by USRC and many others
Green Buildings Resilient Buildings

51. 51ARUP

52. 52
Recognizing that Structures
are Critical to Safety,
Resilience and Sustainability
of the Society
A Final Note

53. 53
Can we make it safe, sustainable and resilient?
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