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

Dr. Naveed Anwar4

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

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 Anwar

Formal, Modern Buildings Codes

7

“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 International Building Code (IBC) by (ICC).

European Union,

the Eurocodes.

Dr. Naveed Anwar8

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 Anwar9

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

10

(ACI 318 – 14)

Extremely Detailed prescriptions and equations using

seemingly arbitrary, rounded limits with

implicit meaning

(IS 456-2000)

Dr. Naveed Anwar

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

Dr. Naveed Anwar12

A Move Towards Performance Based

• Prescriptive Codes restrict and discourage innovation

• Performance Based approach encourages and liberates it

Objective RequirementsPrescribed

Solution

Objective RequirementsAlternate Solution

Dr. Naveed Anwar

Ensuring Explicit Safety Performance(And increase Disaster Resilience)

Dr. Naveed Anwar14

Common Hazards leading to Safety Concerns

Dr. Naveed Anwar15

Indicator Level

Earthquake Related

Wind Related Water Related Fire Related

GlobalDrift, Overturning, Sliding

Drift, Overturning, Sliding, Uplift

Sliding, Floatation Stability

MemberStrength, Ductility, Deformation

Strength, Deformation,

Water tightness, Strength, Deformation

Fire rating

ConnectionStrength, Ductility, Stability

Strength, Stability Strength, Stability, water tightness

Fire rating

Material Ductility, Strength Wind perviousWater proof/ water resistant

Fire proof, fire resistant

Broad Performance Indicators

Dr. Naveed Anwar16

Integrated Disaster Resilient Design

Design

Process Step

Design Considerations

Earthquakes Cyclones, Typhoons Floods Landslide

Loc

atio

n

Pla

n &

La

yo

ut

Ap

pro

pria

te

Ma

teria

l

Str

en

gth

&

inte

grity

Eva

cu

atio

n

Loc

atio

n

De

sig

n E

lem

en

ts

Ma

teria

l

Se

lec

tio

n

Str

en

gth

&

inte

grity

De

bris

Loc

atio

n

Ba

sic

De

sig

n

Mitig

atio

n P

lan

Ma

teria

l U

sag

e

Loc

atio

n

Mitig

atio

n P

lan

Site Selection

Construction

Practices

Architectural Planning

Structural Design

Plumbing Design

Electrical

Waste Disposal

Material Selection

Regional Planning

Dr. Naveed Anwar17

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

Dr. Naveed Anwar18

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”

Dr. Naveed Anwar19

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 Anwar20

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

Dr. Naveed Anwar

Define Performance Levels

21

Based on FEMA 451 B

Dr. Naveed Anwar

Link the Hazard to Performance Levels

22

Structural Displacement

Lo

adin

g S

ever

ity

Resta

urant

Resta

urant

Resta

uran

t

Haz

ard

Vulnerability

Consequences

Dr. Naveed Anwar23

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.

Dr. Naveed Anwar

How to Apply PBD

Dr. Naveed Anwar25

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

Dr. Naveed Anwar26

Structural System

Source: NEHRP Seismic Design Technical Brief No.

3

Dr. Naveed Anwar27

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”

Dr. Naveed Anwar28

Required Information

• Basis of design

• Geotechnical investigation report

• Site-specific probabilistic seismic hazard assessment report

• Wind tunnel test report

Dr. Naveed Anwar29

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

Dr. Naveed Anwar30

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

Dr. Naveed Anwar31

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

Dr. Naveed Anwar32

Depth-varying Ground Motions along Pile Length

Dr. Naveed Anwar33

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)

Dr. Naveed Anwar34

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

Dr. Naveed Anwar

Performance-based Design Procedure

Dr. Naveed Anwar36

Overall PBD Process

Initial Investigati

ons

Preliminary Design

Wind Tunnel

Test

Detailed Code Based Design

Service Level

Evaluation

Collapse Level

Evaluation

Peer Review

Final Design

Dr. Naveed Anwar37

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

Dr. Naveed Anwar38

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)

Dr. Naveed Anwar39

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

Dr. Naveed Anwar40

Scaling of Response Spectrum Analysis Results

Source: FEMA P695 | June 2009

Dr. Naveed Anwar41

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.

Dr. Naveed Anwar42

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.

Dr. Naveed Anwar43

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.

Dr. Naveed Anwar44

Expected Material Strengths

Source: LATBSDC

2014

Dr. Naveed Anwar45

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.

Dr. Naveed Anwar46

• 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

Dr. Naveed Anwar47

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

Dr. Naveed Anwar48

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 Mathematical Models

Dr. Naveed Anwar

Evaluation of Results

Dr. Naveed Anwar50

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.

Dr. Naveed Anwar51

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

Dr. Naveed Anwar52

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

Dr. Naveed Anwar53

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

Story 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

Dr. Naveed Anwar54

0

10

20

30

40

50

60

70

0.000 0.005 0.010 0.015 0.020

Story 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

Dr. Naveed Anwar55

0

10

20

30

40

50

60

70

-3 -2 -1 0 1 2 3

Story level

Lateral displacement (m)

Lateral Displacement

GM-1059

GM-65010

GM-CHY006

GM-JOS

GM-LINC

GM-STL

GM-UNIO

Average

Dr. Naveed Anwar56

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

Story level

Absolute acceleration (g)

Floor Acceleration

GM-1059

GM-65010

GM-CHY006

GM-JOS

GM-LINC

GM-STL

GM-UNIO

Average

Dr. Naveed Anwar57

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)

Energ

y d

issip

atio

n

(%

)

Time (sec)

Energ

y d

issip

atio

n

(%

)

Energ

y d

issip

atio

n

(%

)

Time (sec)

Dr. Naveed Anwar58

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

Dr. Naveed Anwar59

How to Work with PBD

Dr. Naveed Anwar60

• 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

Dr. Naveed Anwar

Value EngineeringBalancing Cost and Performance

Dr. Naveed Anwar62

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

Dr. Naveed Anwar63

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>

Dr. Naveed Anwar64

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

Dr. Naveed Anwar65

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

Dr. Naveed Anwar66

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

Dr. Naveed Anwar67

• 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

Dr. Naveed Anwar68

Cost and Performance

(Base Cost and Performance)

(Increased Performance, Same Cost)

(Base Cost and Performance)

(Reduced Cost for Same Performance)

P

M

P

M

Dr. Naveed Anwar69

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.

Dr. Naveed Anwar70

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

Dr. Naveed Anwar71

Focus should be

“Maximum Value for Resources”

Cost effective, not Low Cost

Dr. Naveed Anwar

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

Dr. Naveed Anwar73

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 Anwar74

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.

Dr. Naveed Anwar75

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

Dr. Naveed Anwar76

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 Anwar

Some Case Studies

Dr. Naveed Anwar78

PBD andAsian 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

Dr. Naveed Anwar79

Gramercy Residences

(72-story)Knightsbridge Residences

(64-story)

Trump Tower

(56-story)

Milano Residences

Some Projects in Makati, Philippines

Dr. Naveed Anwar80

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

Dr. Naveed Anwar81

81

Acqua Private ResidencesMandaluyong City,

Philippines

Niagara Tower

(42-story )

Sutherland Tower

(44-story)

Dettifoss Tower

(46-story)

Livingstone Tower

(53-story)

Dr. Naveed Anwar82

Ninoy AcquinoInternational 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

82

Dr. Naveed Anwar83

Star View ResidencesBangkok

Dr. Naveed Anwar84

R & D to Enhance Performance

Dr. Naveed Anwar85

Application of PBD to PC Hybrid Buildings

Dr. Naveed Anwar86

Dr. Naveed Anwar87

The Plan

Dr. Naveed Anwar88

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 FloorsRC Columns

Roof

Code Based Design – Linear Model PBD – Nonlinear Model

Dr. Naveed Anwar89

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

Dr. Naveed Anwar90

Client

PBD Value Engineering

Peer Review

Basic Design

Public Officials

Design Codes and Guidelines

High performance, Higher safetyhigher value, cost effectiveSustainable

Excellence in Construction

Dr. Naveed Anwar91