performance based design, value naveed anwar, phd
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Dr. Naveed Anwar
Performance Based Design, Value Engineering and Peer Review
Naveed Anwar, PhD
Dr. Naveed Anwar2
Excellencethe quality of being outstanding or
extremely good
Dr. Naveed Anwar3
To be Excellent, something must be above average, better than standard,and of higher performance
How to achieve excellence through innovative, explicit, verifiable and demontratable process
Dr. Naveed Anwar4
Building Industry relies on Codes and Standards
• Codes Specify requirements
• Give acceptable solutions
• Prescribe (detailed) procedures, rules, limits
• (Mostly based on research and experience but not always rational)
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
Dr. Naveed Anwar5
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
Dr. Naveed Anwar6
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
PrescriptiveLaw of Moses (1300 BC)
The Bible, Book of Deuteronomy, Chapter 22, Verse 8
Performance Oriented
Ref: Teh Kem, Associate Prof. NUS
Dr. Naveed Anwar7
Public Safety and Codes
Railing height “deemed” sufficient by the code(Acceptable to residents of lower floors)
Railing height added by resident to “feel safe”
and reduce “”risk” (Only done by residents of higher floors)
Dr. Naveed Anwar8
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
Dr. Naveed Anwar9
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
Dr. Naveed Anwar10
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 …
Dr. Naveed Anwar
The Modern Codes – With “intent” to make buildings safe for public
11
(ACI 318 – 14)
Extremely Detailed prescriptions and equations using
seemingly arbitrary, rounded limits with
implicit meaning
(IS 456-2000)
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A Move Towards Performance Based
• Prescriptive Codes restrict and discourage innovation
• Performance Based approach encourages and liberates it
Objective RequirementsPrescribed
Solution
Objective RequirementsAlternate Solution
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Ensuring Explicit Safety Performance(And increase Disaster Resilience)
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Design Approaches
Intuitive Design
Code Based Design
Performance Based Design
-
Wind
Earthquake
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Performance based design
can be applied to any type
of loads, but was initially
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
GuidelinesPeer Review
Dr. Naveed Anwar18
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
19
Based on FEMA 451 B
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Link the Hazard to Performance Levels
20
Structural Displacement
Lo
adin
g S
ever
ity
Resta
urant
Resta
urant
Resta
uran
t
Haz
ard
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
SP
EC
TR
AL
AC
CELE
RA
TIO
N
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 Investigations
Preliminary 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
development
• 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 (or more) 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 wallsFlexure 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
GirdersFlexure Deformation-controlled N/A
Shear Force-controlled Non-critical
ColumnsAxial-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 wallsFlexure Force-controlled Non-critical
Shear Force-controlled Critical
Mat foundationFlexure Force-controlled Non-critical
Shear Force-controlled Critical
PilesAxial-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 wallsFlexural – 0.75 IgShear – 1.0 Ag
Flexural – 0.6 IgShear – 1.0 Ag
Flexural – **
Shear – 0.2 Ag
Basement wallsFlexural – 1.0 IgShear – 1.0 Ag
Flexural – 0.8 IgShear – 0.8 Ag
Flexural – 0.8 IgShear – 0.5 Ag
Coupling beams
(Diagonal-reinforced)
Flexural –0.3 IgShear – 1.0 Ag
Flexural –0.2 IgShear – 1.0 Ag
Flexural – 0.2 IgShear – 1.0 Ag
Coupling beams
(Conventional-reinforced)
Flexural –0.7 IgShear – 1.0 Ag
Flexural –0.35 IgShear – 1.0 Ag
Flexural – 0.35 IgShear – 1.0 Ag
Ground level diaphragm
(In-plane only)
Flexural – 0.5 IgShear – 0.8 Ag
Flexural – 0.25 IgShear – 0.5 Ag
Flexural – 0.25 IgShear – 0.25 Ag
Podium diaphragmsFlexural – 0.5 IgShear – 0.8 Ag
Flexural – 0.25 IgShear – 0.5 Ag
Flexural – 0.25 IgShear – 0.25 Ag
Tower diaphragmsFlexural – 1.0 IgShear – 1.0 Ag
Flexural – 0.5 IgShear – 0.5 Ag
Flexural – 0.5 IgShear – 0.5 Ag
GirdersFlexural – 0.7 IgShear – 1.0 Ag
Flexural – 0.35 IgShear – 1.0 Ag
Flexural – 0.35 IgShear – 1.0 Ag
ColumnsFlexural – 0.9 IgShear – 1.0 Ag
Flexural – 0.7 IgShear – 1.0 Ag
Flexural – 0.7 IgShear – 1.0 Ag
Stiffness Assumptions in Analysis 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
Base s
hear
(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
Base s
hear
(%)
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
Sto
ry level
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 0.002 0.004 0.006 0.008 0.010 0.012 0.014 0.016
Sto
ry level
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
Sto
ry level
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
Sto
ry level
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
From shear walls Conventional reinforced coupling beams
Total dissipated energy
Total dissipated energy
Diagonal reinforced coupling
beams
Time (sec)
En
erg
y d
issip
ati
on (%
)
Time (sec)
Energ
y d
issip
ati
on
(%)
Energ
y d
issip
ati
on
(%)
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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Integrated PBD for Earthquake and Wind
Dr. Naveed Anwar
Earthquake and Wind PBD are Compatible!
59
Site specific Seismic Hazard Study
Site specific Climate Analysis
Various Earthquake levelsSLE, 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
EarthquakeWind
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Possible Way forward
Consider winds of higher intensity and
longer return periods
Determine static and dynamic impacts
through wind tunnel studies
Incorporate wind tunnel dynamic
measurements into dynamic analysis of structural models
Set appropriate performance criteria
for motion, deformation,
strength, ductility, energy decimation
etc.
Make the Wind PPD consistent with
Earthquake PBD
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Wind Pressure Variation and Dynamic effects
61
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SuggestedStructural Performance Criteria for Wind
Wind Return Period
Wind Performance
Level
Structural System Response
Overall Damage
Wind Performance
ObjectiveDesign Criteria
1 yearPerception Threshold
No Permanent Interstory
UndamageNone Perception
of movementBldg. Acceleration <5
milli -g
10 years Motion Comfort No Permanent
InterstoryUndamage
Controlled Comfort
Bldg. Acceleration <15 milli -g
50 years OperationalNo Permanent
InterstoryUndamage
Non-Structural Damage
Story drift is limited to 0.2%
100 yearsLimited
InterruptionNo Permanent
InterstoryMinor
DamagesStructural Damage
Story drift is limited to 0.3%
475 years Life SafetyPermanent Interstory
Major Damages
No CollapseStory drift is limited
to 0.5% Residual Drift < h/600
1000 years
Collapse Prevention
Permanent Interstory
Extensive Damages
No Collapse
Story drift is limited to 1%
Residual Drift < h/500
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Compare
PBD Wind and PBD Earthquake
(Using ASCE 41 as a sample)
Wind Earthquake
Time Varying Loading Wind Tunnel Testing Site Specific Investigation
LoadingMean + Fluctuating +
Resonant Fluctuating + Resonant
Overall Structural Damage ASCE 41-13 ASCE 41-13
Structural System Response ASCE 41-13 ASCE 41-13
Members Deformation Control Limits
ASCE 41-13 ASCE 41-13
Material Behavior Uncrack to Crack under yield to Crack beyond yield point
Crack under yield to Crack beyond yield point
Structural members controlled
Some members are Force and Deformation Controlled
Some Members are Force and Deformation Controlled
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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
68
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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 relationshipbetween affects of load and ability of member to resists thoseaffects.
• This is a normalized factor that means D/C ratio value of 1 indicatesthat the capacity (strength, deformation etc) member is justenough 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/ CapacityColumns
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 ReviewTo 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
Dr. Naveed Anwar79
Client
PBD Value Engineering
Peer Review
Basic Design
Public Officials
Design Codes and Guidelines
High performance, Higher safetyhigher value, cost effectiveSustainable
Excellence is Structures
Dr. Naveed Anwar80
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