Performance Based Design, Value

Performance Based Design, Value Naveed Anwar, PhD Engineering and Peer Review . Dr. Naveed Anwar 2 ... we need tp estimate hazard properly, ... Struct...

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Naveed Anwar, PhD Dr. Naveed Anwar

Performance Based Design, Value Engineering and Peer Review

Excellence the quality of being outstanding or extremely good Dr. Naveed Anwar

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

Dr. Naveed Anwar

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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

Dr. Naveed Anwar

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The First Code - Hammurabi's (1772 BC)

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

Dr. Naveed Anwar

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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” -

Prescriptive

Performance Oriented

Modern Codes, c2000

Law of Moses (1300 BC)

Ref: Teh Kem, Associate Prof. NUS

The Bible, Book of Deuteronomy, Chapter 22, Verse 8

Dr. Naveed Anwar

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Formal, Modern Buildings Codes

“Rebuilding of London Act” after the “Great Fire of London” in 1666 AD.

In 1680 AD, “The Laws of Indies” Spanish Crown

Dr. Naveed Anwar

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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Lack of Resources for Communities

Inappropriate Built Environment

Natural or Man-made Phenomena

Disaster

Population

Urbanization and Unplanned development

Hazard Vulnerability Exposure Risk

To reduce risk of disaster and increase safety, we need tp estimate hazard properly, and Reduce Vulnerability Dr. Naveed Anwar

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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 … Dr. Naveed Anwar

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The Modern Codes – With “intent” to make buildings safe for public

(ACI 318 – 14)

Extremely Detailed prescriptions and equations using seemingly arbitrary, rounded limits with implicit meaning

(IS 456-2000) Dr. Naveed Anwar

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The General Structural Code Families

UBC, IBC

ACI, PCI, CRSI, ASCE, AISI, AASHTO

Euro-codes

Dr. Naveed Anwar

BS, SG, IS, MNBC, NBC, PBC, ….

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

Dr. Naveed Anwar

Objective

Requirements

Prescribed Solution

Objective

Requirements

Alternate Solution

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Ensuring Explicit Safety Performance (And increase Disaster Resilience)

Dr. Naveed Anwar

Common Hazards leading to Safety Concerns

Dr. Naveed Anwar

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Broad Performance Indicators 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

Dr. Naveed Anwar

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Integrated Disaster Resilient Design Design Considerations

Mitigation Plan

Location

Material Usage

Landslide

Mitigation Plan

Basic Design

Location

Floods

Debris

Strength & integrity

Material Selection

Design Elements

Location

Evacuation

Cyclones, Typhoons

Strength & integrity

Appropriate Material

Location

Design Process Step

Plan & Layout

Earthquakes

Site Selection Construction Practices

Architectural Planning

Structural Design

Plumbing Design Electrical Waste Disposal

Material Selection

Regional Planning

Dr. Naveed Anwar

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Earthquakes as a Catylist for PBD

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

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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)

Dr. Naveed Anwar

Codes arbitrary implicit “Design Level”

Collapse-level Assessment Ensure Collapse prevention under extreme hazards (the largest earthquake with a return period of 2500 years)

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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?

Dr. Naveed Anwar

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 Serviceability: Structure to remain exceedance in 30 years (43-year return essentially elastic with minor damage to period) structural and non-structural elements

Design Basis Earthquake (DBE): 10% Code Level: Moderate probability of exceedance in 50 years damage; extensive repairs (475-year return period) required

structural may be

Maximum Considered Earthquake (MCE): Collapse Prevention: Extensive structural 2% probability of exceedance in 50 years damage; repairs are required and may (2475-year return period) not be economically feasible Dr. Naveed Anwar

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Define Performance Levels

Based on FEMA 451 B Dr. Naveed Anwar

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Link the Hazard to Performance Levels sta Re nt ura

Loading Severity

Resta urant

Consequences

Hazard

Resta urant

Vulnerability Dr. Naveed Anwar

Structural Displacement

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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. Dr. Naveed Anwar

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How to Apply PBD

Dr. Naveed Anwar

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 Anwar

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Structural System

Dr. Naveed Anwar

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 Dr. Naveed Anwar

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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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Response Spectra 2.5

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)

SPECTRAL ACCELERATION



2.0

1.5

1.0

SLE (g)

DBE (g) MCE (g) 0.5

0.0 0.0

2.0

4.0

6.0

8.0

NATURAL PERIOD (SEC)

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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

Dr. Naveed Anwar

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Performance-based Design Procedure

Dr. Naveed Anwar

Overall PBD Process

Initial Investigati ons

Dr. Naveed Anwar

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

Dr. Naveed Anwar

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 Dr. Naveed Anwar

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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. Dr. Naveed Anwar

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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.

Dr. Naveed Anwar

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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.

Dr. Naveed Anwar

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Expected Material Strengths

Dr. Naveed Anwar

Source: LATBSDC 2014

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Deformationcontrolled Actions •

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. Force-deformation relationship for deformation-controlled actions Dr. Naveed Anwar

Source: ASCE/SEI 41-13

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Force-controlled Actions • 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 lifethreatening damage. • Mean value of demand from seven sets of ground motions is used with a factor of 1. Dr. Naveed Anwar

Force-deformation relationship for force-controlled actions Source: ASCE/SEI 41-13

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Classification of Actions Component Shear walls Coupling beams (Conventional)

Coupling beams (Diagonal) Girders Columns Diaphragms Basement walls

Mat foundation Piles Dr. Naveed Anwar

Action

Classification

Criticality

Flexure Shear Flexure Shear Shear Flexure Shear Axial-Flexure Shear Flexure Shear (at podium and basements) Shear (tower) Flexure Shear Flexure Shear Axial-Flexure Shear

Deformation-controlled Force-controlled Deformation-controlled Force-controlled Deformation-controlled Deformation-controlled Force-controlled Deformation-controlled Force-controlled Force-controlled Force-controlled Force-controlled Force-controlled Force-controlled Force-controlled Force-controlled Force-controlled Force-controlled

N/A Critical N/A Non-critical N/A N/A Non-critical N/A Critical Non-critical Critical Non-critical Non-critical Critical Non-critical Critical Non-critical Critical 47

Stiffness Assumptions in Mathematical Models Concrete Element Core walls/shear walls Basement walls

Coupling beams (Diagonal-reinforced) Coupling beams (Conventional-reinforced) Ground level diaphragm (In-plane only) Podium diaphragms Tower diaphragms Girders Columns Dr. Naveed Anwar

SLE/Wind Flexural – 0.75 Ig Shear – 1.0 Ag Flexural – 1.0 Ig Shear – 1.0 Ag Flexural –0.3 Ig Shear – 1.0 Ag Flexural –0.7 Ig Shear – 1.0 Ag Flexural – 0.5 Ig Shear – 0.8 Ag Flexural – 0.5 Ig Shear – 0.8 Ag Flexural – 1.0 Ig Shear – 1.0 Ag Flexural – 0.7 Ig Shear – 1.0 Ag Flexural – 0.9 Ig Shear – 1.0 Ag

DBE Flexural – 0.6 Ig Shear – 1.0 Ag Flexural – 0.8 Ig Shear – 0.8 Ag Flexural –0.2 Ig Shear – 1.0 Ag Flexural –0.35 Ig Shear – 1.0 Ag Flexural – 0.25 Ig Shear – 0.5 Ag Flexural – 0.25 Ig Shear – 0.5 Ag Flexural – 0.5 Ig Shear – 0.5 Ag Flexural – 0.35 Ig Shear – 1.0 Ag Flexural – 0.7 Ig Shear – 1.0 Ag

MCE Flexural – ** Shear – 0.2 Ag Flexural – 0.8 Ig Shear – 0.5 Ag Flexural – 0.2 Ig Shear – 1.0 Ag Flexural – 0.35 Ig Shear – 1.0 Ag Flexural – 0.25 Ig Shear – 0.25 Ag Flexural – 0.25 Ig Shear – 0.25 Ag Flexural – 0.5 Ig Shear – 0.5 Ag Flexural – 0.35 Ig Shear – 1.0 Ag Flexural – 0.7 Ig Shear – 1.0 Ag 48

Evaluation of Results

Dr. Naveed Anwar

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 Anwar

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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 16.0

300,000

14.67

269,170

14.0 12.0

201,762

200,000

Base shear (%)

Base shear (kN)

250,000

160,409

150,000

133,233

100,000

10.0

8.74

8.0

7.26

6.0 4.42

81,161

4.0

57,826 50,000

11.00

39,137

30,878

X

Dr. Naveed Anwar

2.13

1.68

0.0

0

Wind (50-yr) x 1.6

2.0

3.15

Along direction

Elastic MCE

X

Y

Inelastic MCE-NLTHA

Elastic SLE

Wind (50-yr) x 1.6

Along direction

Elastic MCE

Y

Inelastic MCE-NLTHA

Elastic SLE

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Transient Drift 70

GM-1059 GM-65010

60

GM-CHY006

50

Story level

GM-JOS

40

GM-LINC GM-STL

30

GM-UNIO

20

Average Avg. Drift Limit

10

Max. Drift Limit

0 -0.05

-0.04

-0.03

-0.02

-0.01

0.00

0.01

0.02

0.03

0.04

0.05

Drift ratio Dr. Naveed Anwar

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Residual Drift

70

GM-1059 GM-65010

60

GM-CHY006

50

Story level

GM-JOS

40

GM-LINC

GM-STL

30

GM-UNIO

20

Average Avg. Drift Limit

10

Max Drift Limit

0 0.000

0.005

0.010

0.015

0.020

Drift ratio Dr. Naveed Anwar

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Lateral Displacement 70 GM-1059

60

GM-65010

GM-CHY006

Story level

50

GM-JOS

40 GM-LINC

30 GM-STL

20

GM-UNIO

10

Average

0

-3

-2

-1

0

1

2

3

Lateral displacement (m) Dr. Naveed Anwar

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Floor Acceleration 70 GM-1059

60

GM-65010

Story level

50

GM-CHY006 GM-JOS

40

GM-LINC

30 GM-STL

20

GM-UNIO

10

Average

0 -2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

Absolute acceleration (g) Dr. Naveed Anwar

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Energy dissipation (%)

Energy dissipation (%)

Energy Dissipation

Total dissipated energy

Total dissipated energy

Dissipated energy from conventional reinforced coupling beams

Dissipated energy from shear walls Time (sec)

Time (sec)

Energy dissipation (%)

Total dissipated energy

Dissipated energy from diagonal reinforced coupling beams

Dr. Naveed Anwar

Time (sec)

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Component Responses Component Pile foundation Mat foundation Shear wall Column Beams Conventional reinforced coupling beam Diagonal reinforced coupling beam Flat slab Basement wall Diaphragm

Dr. Naveed Anwar

Response Bearing capacity, pullout capacity, PMM, shear Bearing capacity, flexure, shear Flexure (axial strain), shear PMM or flexural rotation, axial, shear Flexural rotation, shear Flexural rotation, shear Shear rotation, shear Flexural rotation, punching shear In-plane shear, out-of-plane flexure and shear Shear, shear friction, tension and compression

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How to Work with PBD

Dr. Naveed Anwar

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Performance Based Design

• Explicit confirmation of higher or expected performance level using innovative solutions

Value Engineering

• Get the best “value” for resources

Peer Review

• Provide an independent view and confirmation

Dr. Naveed Anwar

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Value Engineering

Balancing Cost and Performance Dr. Naveed Anwar

Cost and Performance

C

C

Dr. Naveed Anwar

P

P

General Belief Easy to do !

High Performance Design Can be done

CC

C

P

Cost Effective Design Can be done

P

Highly Innovative Design Hard to do! 62

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

Dr. Naveed Anwar

Cost may be:

“Consumption of Particular Resources, at Particular Time”

Sustainability may be:

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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

Dr. Naveed Anwar

• Cost Effectiveness • • • • • •

Capacity utilization ratio Reinforcement ratios Reinforcement volume ratios Concrete strength and quantity Rebar quantity Constructability, time and accommodation of other constraints

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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 Dr. Naveed Anwar

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Levels of Optimization

Levels of Optimization

Micro-Micro Level

One part of a component, “Steel”

Dr. Naveed Anwar

Micro Level

One Component, “Column”

Local

One part or aspect

Global

Entire Problem, Project

Universal

Entire System

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Local Vs Global Optimization • 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 ??

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Cost and Performance P

(Increased Performance, Same Cost) (Base Cost and Performance)

M P

(Reduced Cost for Same Performance) (Base Cost and Performance)

M Dr. Naveed Anwar

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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. Dr. Naveed Anwar

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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)

Dr. Naveed Anwar

Columns

Not Cost Effective

Ideal Not Safe

Demand/ Capacity No.

%

D/C<0.5

178

16%

0.5
534

49%

0.7
346

31%

1
30

3%

1.5
12

1%

D/C>2.5

0

0%

Total

1100

100.00%

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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

Dr. Naveed Anwar

The Responsibility Client/Owner

General Building Codes

Architect

Structural Design Codes

Structural Designer

Law Makers

Geotech Consultants

Building Officials

Peer Reviewer

Legal and Justice System

Builder/Contractor Public/ Users/ Occupants Dr. Naveed Anwar

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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.

Dr. Naveed Anwar

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When is Peer Review needed

New York Building Code, adopted by many cities

• 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. Dr. Naveed Anwar

Important

Slender Tall or large Critical Use NLA 75

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.

Retains 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 Dr. Naveed Anwar

Evaluates, and gives opinion that may or may not be accepted by Client or SER 76

Some Case Studies

Dr. Naveed Anwar

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

Dr. Naveed Anwar

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Knightsbridge Residences

(64-story)

Milano Residences

Gramercy Residences

(72-story) Trump Tower

(56-story)

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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Dettifoss Tower Sutherland Tower

(44-story)

(46-story) Livingstone Tower

(53-story)

Niagara Tower

(42-story )

Dr. Naveed Anwar

Acqua Private Residences Mandaluyong City, Philippines

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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 Dr. Naveed Anwar

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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 Roof

Residential Floors Cast-in-Place Shear Walls 117.9 m (38 Stories) Precast Concrete Walls

RC Walls

Transfer Beams Car Parking Floors RC Columns

Code Based Design – Linear Model

Dr. Naveed Anwar

PBD – Nonlinear Model

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PBD Findings and Fixes No. 1 2

3 4

Components Shear Walls Columns

RC Walls PC Walls

Actions

Comments for Seismic Evaluation at MCE level

Flexure

OK

Shear

Increase horizontal reinforcements and wall thickness

Flexure

OK

Shear

Increase horizontal reinforcements and column size

Flexure

Increase confinement reinforcements (2 Stories)

Shear

Increase horizontal reinforcements (2 Stories)

Flexure

Increase confinement reinforcements (2 Stories)

Shear

Increase horizontal reinforcements (2 Stories)

5

Plies

Axial

OK

6

Foundations

Flexure

OK

Shear

OK

Flexure

Increase longitudinal reinforcements

Shear

Increase horizontal reinforcements

Flexure

OK

Shear

Increase horizontal reinforcements

7 8

Transfer Beams Coupling Beams

Dr. Naveed Anwar

89

Excellence in Construction Design Codes and Guidelines

High performance, Higher safety higher value, cost effective Sustainable

Basic Design Peer Review

PBD

Value Engineering

Client Public Officials Dr. Naveed Anwar

90

Dr. Naveed Anwar

91