Presented at Design of Tall Buildings and Affordable Housing ,12 March 2017, Sultan Qaboos University, Muscat, Oman

1. Dr. Naveed Anwar
Performance Based Design, Value
Engineering and Peer ReviewNaveed Anwar, PhD

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Excellence
the quality of being outstanding or
extremely good

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To be Excellent, something must
be above average, better than standard,
and of higher performance

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Building Industry relies on Codes and Standards
• Specify requirements
• Give acceptable solutions
• Prescribe (detailed) procedures, rules, limits
• Mostly based on experience and not always rational
• Spirit of the code to provide Public Safety and Convenience
• Compliance to letter of the code is indented to meet the spirit

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The First Code - Hammurabi's (1772 BC)
Clause 229: If a builder builds a house for someone, and
does not construct it properly, and the house which he
built falls in and kills its owner, then that builder
shall be put to death.
Implicit Requirements
Consequence of non-Performance
Explicit Collapse Performance

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Public Safety and the Codes
-
“In case you build a new house, you
must also make a parapet for your
roof, that you may not place
bloodguilt upon your house because
someone falling might fall from it”
Modern Codes, c2000
Prescriptive
Law of Moses (1300 BC)
The Bible, Book of Deuteronomy, Chapter 22, Verse 8
Performance Oriented
Ref: Teh Kem, Associate Prof. NUS

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Formal, Modern Buildings Codes
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“Rebuilding
of London
Act” after
the “Great
Fire of
London” in
1666 AD.
In 1680 AD,
“The Laws of
Indies” Spanish
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 Internatio
nal Building
Code (IBC)
by (ICC).
European
Union,
the Eurocodes
.

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Population
Urbanization and Un-
planned
development
Inappropriate
Built
Environment
Lack of Resources
for Communities
Natural or
Man-made
Phenomena
Disaster Hazard ExposureVulnerability
To reduce risk of disaster and increase safety,
we need tp estimate hazard properly,
and Reduce Vulnerability
Risk

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How modern codes intent to ensure “Safety”
• Define appropriate/estimated hazard or load levels
• Prescribe limits on structural systems, members, materials
• Define procedures for analysis and design
• Provide rules for detailing
• Provide specifications for construction and monitoring
•Hope that all of this will lead to reduced vulnerability
and safer structures …

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The Modern Codes – With “intent” to make buildings safe for public
10
(ACI 318 – 14)
Extremely Detailed
prescriptions and
equations using
seemingly arbitrary,
rounded limits with
implicit meaning
(IS 456-2000)

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The General Structural Code Families
11
UBC, IBC
ACI, PCI, CRSI, ASCE,
AISI,
AASHTO
BS, SG, IS, MNBC,
NBC, PBC, ….
Euro-codes China, USSR, Japan

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A Move Towards Performance Based
• Prescriptive Codes
restrict and discourage
innovation
• Performance Based
approach encourages
and liberates it
Objective Requirements
Prescribed
Solution
Objective Requirements
Alternate
Solution

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Ensuring Explicit Safety Performance
(And increase Disaster Resilience)

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Common Hazards leading to Safety Concerns

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Indicator
Level
Earthquake
Related
Wind Related Water Related Fire Related
Global
Drift, Overturning,
Sliding
Drift, Overturning,
Sliding, Uplift
Sliding, Floatation Stability
Member
Strength, Ductility,
Deformation
Strength,
Deformation,
Water tightness,
Strength,
Deformation
Fire rating
Connection
Strength, Ductility,
Stability
Strength, Stability Strength, Stability,
water tightness
Fire rating
Material Ductility, Strength Wind pervious
Water proof/
water resistant
Fire proof, fire
resistant
Broad Performance Indicators

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Integrated Disaster Resilient Design
Design
Process Step
Design Considerations
Earthquakes Cyclones, Typhoons Floods Landslide
Location
Plan&Layout
Appropriate
Material
Strength&
integrity
Evacuation
Location
DesignElements
Material
Selection
Strength&
integrity
Debris
Location
BasicDesign
MitigationPlan
MaterialUsage
Location
MitigationPlan
Site Selection
Construction
Practices
Architectural Planning
Structural Design
Plumbing Design
Electrical
Waste Disposal
Material Selection
Regional Planning

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Performance based design
can be applied to any type
of loads, but was initaily
developed and targeted for
earthquake loads
Earthquakes as a Catylist for PBD

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Explicit Performance Objective in PBD
Performance based design investigates at least two
performance objectives explicitly
Service-level
Assessment
Ensure continuity of service for
frequent hazards
(Earthquake having a return period
of about 50)
Collapse-level
Assessment
Ensure Collapse prevention
under extreme hazards
(the largest earthquake with a
return period of 2500 years)
Codes arbitrary
implicit
“Design Level”

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Performance Level Definitions
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

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Performance Objectives for Seismic Design
Level of Earthquake Seismic Performance Objective
Frequent/Service (SLE): 50% probability of
exceedance in 30 years (43-year return
period)
Serviceability: Structure to remain
essentially elastic with minor damage to
structural and non-structural elements
Design Basis Earthquake (DBE): 10%
probability of exceedance in 50 years
(475-year return period)
Code Level: Moderate structural
damage; extensive repairs may be
required
Maximum Considered Earthquake (MCE):
2% probability of exceedance in 50 years
(2475-year return period)
Collapse Prevention: Extensive structural
damage; repairs are required and may
not be economically feasible

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Define Performance Levels
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Based on FEMA 451 B

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Link the Hazard to Performance Levels
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Structural Displacement
LoadingSeverity
Resta
urant
Resta
urant
Resta
urant
Hazard
Vulnerability
Consequences

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Performance-based design
• More explicit evaluation of the safety and reliability of structures.
• Provides opportunity to clearly define the levels of hazards to be designed
against, with the corresponding performance to be achieved.
• Code provisions are intended to provide a minimum level of safety.
• Shortcoming of traditional building codes (for seismic design) is that the
performance objectives are considered implicitly.
• Code provisions contain requirements that are not specifically applicable to
tall buildings which may results in designs that are less than optimal, both
from a cost and safety perspective.
• Verify that code-intended seismic performance objectives are met.

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How to Apply PBD

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The Building Structural System - Conceptual
• The Gravity Load Resisting System
• The structural system (beams, slab, girders, columns, etc.) that acts primarily
to support the gravity or vertical loads
• The Lateral Load Resisting System
• The structural system (columns, shear walls, bracing, etc.) that primarily acts
to resist the lateral loads
• The Floor Diaphragm
• The structural system that transfers lateral loads to the lateral load resisting
system and provides in-plane floor stiffness

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Structural System
Source: NEHRP Seismic Design Technical Brief No.
3

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PBD Guidelines
• PEER 2010/05, “Tall Building Initiative, Guidelines for
Performance Based Seismic Design of Tall Buildings”
• PEER/ATC 72-1, “Modeling and Acceptance Criteria for
Seismic Design and Analysis of Tall Buildings”
• ASCE/SEI 41-13, “Seismic Evaluation and Retrofit of
Existing Buildings”
• LATBSDC 2014, “An Alternative Procedure for Seismic
Analysis and Design of Tall Buildings Located in the Los
Angeles Region”

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Required Information
• Basis of design
• Geotechnical investigation report
• Site-specific probabilistic seismic hazard assessment report
• Wind tunnel test report

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Basis of Design
• Description of building
• Structural system
• Codes, standards, and references
• Loading criteria
• Gravity load, seismic load, wind load
• Materials
• Modeling, analysis, and design procedures
• Acceptance criteria

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Geotechnical Investigation Report
• SPT values
• Soil stratification and properties
• Soil type for seismic loading
• Ground water level
• Allowable bearing capacity (Factors to increase in capacity for transient loads and
stress peaks)
• Sub-grade modulus (Vertical and lateral)
• Liquefaction potential
• Pile foundation
• Ultimate end bearing pressure vs. pile length
• Ultimate skin friction pressure vs. pile length
• Allowable bearing capacity
• Allowable pullout capacity
• Basement wall pressure

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Site-specific Probabilistic Seismic Hazard Assessment Report
• Recommend response spectra (SLE, DBE, MCE)
• Ground motions scaled for MCE spectra
• If piles are modeled in nonlinear model,
• Depth-varying ground motions along the pile length
• Springs and dashpots
• If vertical members are restrained at pile cap level,
• Amplified ground motions at surface level

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Depth-varying Ground Motions along Pile Length

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0.0
0.5
1.0
1.5
2.0
2.5
0.0 2.0 4.0 6.0 8.0
SPECTRALACCELERATION
NATURAL PERIOD (SEC)
Response Spectra
SLE (g)
DBE (g)
MCE (g)
Response Spectra
• Service Level Earthquake (SLE)
• 50% of probability of exceedance in 30 years
(43-year return period)
• Design Basis Earthquake (DBE)
• 10% of probability of exceedance in 50 years
(475-year return period)
• Maximum Considered Earthquake
(MCE)
• 2% of probability of exceedance in 50 years
(2475-year return period)

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Wind Tunnel Test Report
• Wind-induced structural loads and building
motion study
• 10-year return period wind load
• 50-year or 700-year return period wind load
• Comparison of wind tunnel test results with various
wind codes
• Floor accelerations (1-year, 5-year return periods)
• Rotational velocity (1-year return period)
• Natural frequency sensitivity study

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Performance-based Design
Procedure

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Overall PBD Process
Initial
Investigati
ons
Preliminar
y Design
Wind
Tunnel
Test
Detailed
Code
Based
Design
Service
Level
Evaluation
Collapse
Level
Evaluation
Peer
Review
Final
Design

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Preliminary design
Structural
system
developme
nt
• Bearing wall
system
• Dual system
• Special moment
resisting frame
• Intermediate
moment resisting
frame
Finite
element
modeling
• Linear analysis
models
• Different stiffness
assumptions for
seismic and wind
loadings
Check
overall
response
• Modal analysis
• Natural period, mode
shapes, modal
participating mass
ratios
• Gravity load
response
• Building weight per
floor area
• Deflections
• Lateral load response
(DBE, Wind)
• Base shear, story drift,
displacement
Preliminary
member
sizing
• Structural density
ratios
• Slab thickness
• Shear wall thickness
• Coupling beam sizes
• Column sizes

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Detailed Code-based Design
• Modeling
• Nominal material properties are used.
• Different cracked section properties for wind and seismic models
• Springs representing the effects of soil on the foundation system and basement walls
• Gravity load design
• Slab
• Secondary beams
• Wind design
• Apply wind loads from wind tunnel test in mathematical model
• Ultimate strength design
• 50-year return period wind load x Load factor
• 700-year return period wind load
• Serviceability check
• Story drift ≤ 0.4%, Lateral displacement ≤ H/400 (10-year return period wind load)
• Floor acceleration (1-year and 5-year return period wind load)

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Detailed code-based design
• Seismic design (DBE)
• Use recommended design spectra of DBE from PSHA
• Apply seismic load in principal directions of the building
• Scaling of base shear from response spectrum analysis
• Consider accidental torsion, directional and orthogonal effects
• 5% of critical damping is used for un-modeled energy dissipation
• Define load combinations with load factors
• Design and detail reinforcement

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Scaling of Response Spectrum Analysis Results
Source: FEMA P695 | June 2009

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SLE Evaluation
• Linear model is used.
• Site-specific service level response spectrum is used without
reduction by scale factors.
• 2.5% of critical damping is used for un-modeled energy dissipation.
• 1.0D + 0.25 L ± 1.0 ESLE
• Seismic orthogonal effects are considered.
• Accidental eccentricities are not considered in serviceability
evaluation.
• Response modification coefficient, overstrength factor, redundancy
factor and deflection amplification factor are not used in
serviceability evaluation.

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Acceptance Criteria (SLE)
• Demand to capacity ratios
• ≤ 1.5 for deformation-controlled actions
• ≤ 0.7 for force-controlled actions
• Capacity is computed based on nominal material properties with the
strength reduction factor of 1.
• Story drift shall not exceed 0.5% of story height in any story with the
intention of providing some protection of nonstructural components
and also to assure that permanent lateral displacement of the
structure will be negligible.

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MCE Evaluation
• Nonlinear model is used.
• Nonlinear response history analysis is conducted.
• Seven pairs of site-specific ground motions are used.
• 2.5% of constant modal damping is used with small fraction of
Rayleigh damping for un-modeled energy dissipation.
• Average of demands from seven ground motions approach is used.
• Capacities are calculated using expected material properties and
strength reduction factor of 1.0.

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Expected Material Strengths
Source: LATBSDC
2014

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Deformation-
controlled Actions
Force-deformation relationship for
deformation-controlled actions
Source: ASCE/SEI 41-13
• Behavior is ductile and reliable inelastic
deformations can be reached with no
substantial strength loss.
• Results are checked for mean value of
demand from seven sets of ground motion
records.

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• Behavior is more brittle and reliable
inelastic deformations cannot be
reached.
• Critical actions
• Actions in which failure mode poses severe
consequences to structural stability under
gravity and/or lateral loads.
• 1.5 times the mean value of demand from
seven sets of ground motions is used.
• Non-critical actions
• Actions in which failure does not result
structural instability or potentially life-
threatening damage.
• Mean value of demand from seven sets of
ground motions is used with a factor of 1.
Force-controlled
Actions
Force-deformation relationship for
force-controlled actions
Source: ASCE/SEI 41-13

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Component Action Classification Criticality
Shear walls
Flexure Deformation-controlled N/A
Shear Force-controlled Critical
Coupling beams
(Conventional)
Flexure Deformation-controlled N/A
Shear Force-controlled Non-critical
Coupling beams (Diagonal) Shear Deformation-controlled N/A
Girders
Flexure Deformation-controlled N/A
Shear Force-controlled Non-critical
Columns
Axial-Flexure Deformation-controlled N/A
Shear Force-controlled Critical
Diaphragms
Flexure Force-controlled Non-critical
Shear (at podium and basements) Force-controlled Critical
Shear (tower) Force-controlled Non-critical
Basement walls
Flexure Force-controlled Non-critical
Shear Force-controlled Critical
Mat foundation
Flexure Force-controlled Non-critical
Shear Force-controlled Critical
Piles
Axial-Flexure Force-controlled Non-critical
Shear Force-controlled Critical
Classification of Actions

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Concrete Element SLE/Wind DBE MCE
Core walls/shear walls
Flexural – 0.75 Ig
Shear – 1.0 Ag
Flexural – 0.6 Ig
Shear – 1.0 Ag
Flexural – **
Shear – 0.2 Ag
Basement walls
Flexural – 1.0 Ig
Shear – 1.0 Ag
Flexural – 0.8 Ig
Shear – 0.8 Ag
Flexural – 0.8 Ig
Shear – 0.5 Ag
Coupling beams
(Diagonal-reinforced)
Flexural –0.3 Ig
Shear – 1.0 Ag
Flexural –0.2 Ig
Shear – 1.0 Ag
Flexural – 0.2 Ig
Shear – 1.0 Ag
Coupling beams
(Conventional-reinforced)
Flexural –0.7 Ig
Shear – 1.0 Ag
Flexural –0.35 Ig
Shear – 1.0 Ag
Flexural – 0.35 Ig
Shear – 1.0 Ag
Ground level diaphragm
(In-plane only)
Flexural – 0.5 Ig
Shear – 0.8 Ag
Flexural – 0.25 Ig
Shear – 0.5 Ag
Flexural – 0.25 Ig
Shear – 0.25 Ag
Podium diaphragms
Flexural – 0.5 Ig
Shear – 0.8 Ag
Flexural – 0.25 Ig
Shear – 0.5 Ag
Flexural – 0.25 Ig
Shear – 0.25 Ag
Tower diaphragms
Flexural – 1.0 Ig
Shear – 1.0 Ag
Flexural – 0.5 Ig
Shear – 0.5 Ag
Flexural – 0.5 Ig
Shear – 0.5 Ag
Girders
Flexural – 0.7 Ig
Shear – 1.0 Ag
Flexural – 0.35 Ig
Shear – 1.0 Ag
Flexural – 0.35 Ig
Shear – 1.0 Ag
Columns
Flexural – 0.9 Ig
Shear – 1.0 Ag
Flexural – 0.7 Ig
Shear – 1.0 Ag
Flexural – 0.7 Ig
Shear – 1.0 Ag
Stiffness Assumptions in Mathematical Models

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Evaluation of Results

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Evaluation of Results
• Results extraction, processing and converting them into presentable
form takes additional time.
• Results interpretation i.e. converting “numbers we have already
crunched” into “meaningful outcome for decision-making”.
• Since each of these performance levels are associated with a physical
description of damage, obtained results are compared and evaluated
based on this criterion to get performance insight.

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Overall Response
• Base shear
• Ratio between inelastic base shear and elastic base shear
• Story drift (Transient drift, residual drift)
• Lateral displacement
• Floor acceleration
• Energy dissipation of each component type
• Energy error

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Base Shear
30,878
81,161
269,170
201,762
160,409
133,233
57,826
39,137
0
50,000
100,000
150,000
200,000
250,000
300,000
X Y
Baseshear(kN)
Along direction
Wind (50-yr) x 1.6 Elastic MCE Inelastic MCE-NLTHA Elastic SLE
1.68
4.42
14.67
11.00
8.74
7.26
3.15
2.13
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
X Y
Baseshear(%)
Along direction
Wind (50-yr) x 1.6 Elastic MCE Inelastic MCE-NLTHA Elastic SLE

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0
10
20
30
40
50
60
70
-0.05 -0.04 -0.03 -0.02 -0.01 0.00 0.01 0.02 0.03 0.04 0.05
Storylevel
Drift ratio
Transient Drift
GM-1059
GM-65010
GM-CHY006
GM-JOS
GM-LINC
GM-STL
GM-UNIO
Average
Avg. Drift Limit
Max. Drift Limit

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0
10
20
30
40
50
60
70
0.000 0.005 0.010 0.015 0.020
Storylevel
Drift ratio
Residual Drift
GM-1059
GM-65010
GM-CHY006
GM-JOS
GM-LINC
GM-STL
GM-UNIO
Average
Avg. Drift Limit
Max Drift Limit

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0
10
20
30
40
50
60
70
-3 -2 -1 0 1 2 3
Storylevel
Lateral displacement (m)
Lateral Displacement
GM-1059
GM-65010
GM-CHY006
GM-JOS
GM-LINC
GM-STL
GM-UNIO
Average

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0
10
20
30
40
50
60
70
-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0
Storylevel
Absolute acceleration (g)
Floor Acceleration
GM-1059
GM-65010
GM-CHY006
GM-JOS
GM-LINC
GM-STL
GM-UNIO
Average

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Energy Dissipation
Total dissipated
energy
Dissipated energy from shear
walls
Dissipated energy from
conventional reinforced coupling
beams
Total dissipated
energy
Total dissipated
energy
Dissipated energy
from diagonal
reinforced coupling
beams
Time (sec)
Energydissipation
(%)
Time (sec)
Energydissipation
(%)
Energydissipation
(%)
Time (sec)

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Component Responses
Component Response
Pile foundation Bearing capacity, pullout capacity, PMM, shear
Mat foundation Bearing capacity, flexure, shear
Shear wall Flexure (axial strain), shear
Column PMM or flexural rotation, axial, shear
Beams Flexural rotation, shear
Conventional reinforced coupling beam Flexural rotation, shear
Diagonal reinforced coupling beam Shear rotation, shear
Flat slab Flexural rotation, punching shear
Basement wall In-plane shear, out-of-plane flexure and shear
Diaphragm Shear, shear friction, tension and compression

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How to Work
with PBD

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• Explicit confirmation of higher or
expected performance level using
innovative solutions
Performance
Based Design
• Get the best “value” for resourcesValue Engineering
• Provide an independent view and
confirmation
Peer Review

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Value Engineering
Balancing Cost and Performance

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Cost and Performance
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

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What is the Cost of a Project?
• Cost may include
– Financial Cost (loan, interest, etc)
– Planning and Design Cost
– Direct Construction Cost
– Maintenance Cost
– Incidental Cost
– Liquidated Cost (lost profit etc)
– Opportunistic Cost
– Environmental Cost
– Emotional Cost
– Non-determinist Resources
Cost may be:
“Consumption of
Particular Resources, at
Particular Time”
Sustainability may be:
<Consumption of all
resources, and their impacts
through throughout the life
cycle>

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Cost and Performance
• Enhancement of Performance
• Dynamic response parameters
• Lateral load response
• Vertical load response
• Demand and capacity ratios
• Response irregularity,
discontinuity
• Explicit Performance Evaluation at
Service, DBE and MCE
• Cost Effectiveness
• Capacity utilization ratio
• Reinforcement ratios
• Reinforcement volume ratios
• Concrete strength and quantity
• Rebar quantity
• Constructability, time and
accommodation of other
constraints
64

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Optimization
• Need to define What to optimize?
And what are the parameters that
can be changes?
• Optimizing one or two items may
“un-optimize” others
• Optimizing everything is a “Holy
Grail”
– …. and “Holy Grail” doesn't exist
• Tools
– Genetic Algorithms (GA)
– Artificial Neural Networks (ANN)
– Linear and Nonlinear programing

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Levels of Optimization
Levels of Optimization
Micro-Micro Level
One part of a component,
“Steel”
Micro Level
One Component,
“Column”
Local
One part or aspect
Global
Entire Problem, Project
Universal
Entire System

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• Simple Example of a Column
Stack – What and how can
we optimize ?
• Concrete Strength
• Steel Strength
• Column Size
• Rebar Amount
• Composite Section
• Material Cost, Labor Cost,
Formwork Cost,
Management and operations
Cost, Time ??
Local Vs Global Optimization

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Cost and Performance
(Base Cost and
Performance)
(Increased Performance,
Same Cost)
(Base Cost and
Performance)
(Reduced Cost for Same
Performance)
P
M
P
M

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Demand Capacity (DC Ratio)
• Definition of D/C: It is an index that gives an overall relationship
between affects of load and ability of member to resists those
affects.
• This is a normalized factor that means D/C ratio value of 1 indicates
that the capacity (strength, deformation etc) member is just
enough to fulfill the load demand.
• Two types of D/C ratio
 Members with brittle behavior D/C is checked by Strength (Elastic)
 Members with ductile behavior D/C is checked by deformation (Inelastic)
• Total D/C ratio of the member is combined of these two.

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Cost Effectiveness > Utilization Ratio
• Utilization Ratio
• Compare, What is
Needed against
What is Required
• One measure
• The Demand/
Capacity Ratio (D/C)
Demand/ Capacity
Columns
No. %
D/C<0.5 178 16%
0.5<D/C<0.7 534 49%
0.7<D/C<1 346 31%
1<D/C<1.5 30 3%
1.5<D/C<2.5 12 1%
D/C>2.5 0 0%
Total 1100 100.00%
Ideal
Not Cost
Effective
Not Safe

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Focus should be
“Maximum Value for Resources”
Cost effective, not Low Cost

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Peer Review
To ensure Basic Design the Performance Evaluation
and Value Enginering are done right

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The Responsibility
Building Officials
Structural Designer
Architect Structural Design Codes
General Building Codes
Legal and Justice System
Public/ Users/ Occupants
Client/Owner
Law Makers
Builder/Contractor
Peer Reviewer
Geotech Consultants

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Peer Review
• What exactly is design peer review?
• It is a process whereby a design project (or aspect of) is reviewed and
evaluated by a person, or team, not directly involved with the project, but
appropriately qualified to provide input that will either reinforce a design
solution, or provide a route to an improved alternative.
• Why is it so important?
• Very few can claim to be all-encompassing experts. The invaluable input from
broad base and independent experience at each stage of a design project will
often result in technical improvements, lower costs, avoidance of sourcing
issues, and improved performance.

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When is Peer Review needed
• Structural Peer Review is required for:
• Buildings included in Structural Occupancy Category
IV as defined in the Building Code.
• Buildings with aspect ratios of seven or greater.
• Buildings greater than 500 feet (160 m) in height or
more than 1,000,000 square feet (100,000 Sqm) in
gross floor area.
• Buildings taller than seven stories where any
element supports in aggregate more than 15
percent of the building area.
• Buildings designed using nonlinear time history
analysis, pushover analysis or progressive loading
techniques.
New York Building Code, adopted by many cities
Important
Slender
Tall or large
Critical
Use NLA

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Responsibility
• Structural Engineer of Record (SER).
• The structural engineer of record shall retain
sole responsibility for the structural design. The
activities and reports of the Reviewing Engineer
shall not relieve the structural engineer of
record of this responsibility.
• Reviewing Engineer.
• The Reviewing Engineer’s report states his or her
opinion regarding the design by the engineer of
record.
• The standard of care to which the Reviewing
Engineer shall be consistent with Structural Peer
Review services performed by professional
engineers licensed/approved
Retains
Responsibility
Evaluates, and
gives opinion that
may or may not
be accepted by
Client or SER

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Some Case Studies

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PBD and
Asian Institute of
Technology, AIT
• Research labs to support
innovation
• More than 70 tall building
projects in Asia
• Carried out for several
developers and structural
engineers
• Many of which further reviewed
by third-party experts based in
the USA

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Gramercy Residences
(72-story)
Knightsbridge Residences
(64-story)
TrumpTower
(56-story)
Milano Residences
Some Projects in
Makati, Philippines

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Park Terraces
• Located in Makati City, Philippines
• Two 50-story towers, one 62 story
tower
• Remove perimeter beams, for
better View
• First application of buckling
restrained brace (BRB) system in
Philippines

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Acqua Private Residences
Mandaluyong City,
Philippines
NiagaraTower
(42-story )
SutherlandTower
(44-story)
DettifossTower
(46-story)
LivingstoneTower
(53-story)

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Ninoy Acquino
International Airport
Terminal 1
• Performance Based Approach used
for Disaster Resilience
• Traditional Code Based Review
would make it unfeasible
• Seismic evaluation and retrofit
design
• Evaluate for “Collapse Prevention”
structural performance level under
strong earthquakes
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Star View Residences
Bangkok

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R & D to Enhance Performance

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Application of PBD to PC Hybrid Buildings

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The Plan

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Modeled and Design for Two Approaches
117.9 m
(38 Stories)
Transfer
Beams
Residential
Floors
Cast-in-Place
Shear Walls
Precast
Concrete Walls
RC Walls
Car Parking Floors
RC Columns
Roof
Code Based Design – Linear Model PBD – Nonlinear Model

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PBD Findings and Fixes
No. Components Actions Comments for Seismic Evaluation at MCE level
1 Shear Walls Flexure OK
Shear Increase horizontal reinforcements and wall thickness
2 Columns Flexure OK
Shear Increase horizontal reinforcements and column size
3 RC Walls Flexure Increase confinement reinforcements (2 Stories)
Shear Increase horizontal reinforcements (2 Stories)
4 PC Walls Flexure Increase confinement reinforcements (2 Stories)
Shear Increase horizontal reinforcements (2 Stories)
5 Plies Axial OK
6 Foundations Flexure OK
Shear OK
7 Transfer Beams Flexure Increase longitudinal reinforcements
Shear Increase horizontal reinforcements
8 Coupling Beams Flexure OK
Shear Increase horizontal reinforcements

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Client
PBD Value
Engineering
Peer
Review
Basic Design
Public Officials
Design Codes and Guidelines
High performance,
Higher safety
higher value,
cost effective
Sustainable
Excellence in Construction

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