utspeaks: our fragile cities (part 1: keith crews)

UTSpeaks: Our fragile cities (part one)Professor Keith Crews – 30 November 2011

Our Fragile Cities ……Sustainability of Infrastructure

Centre for Built Infrastructure ResearchUniversity of Technology Sydney

Keith Crews

Professor of Structural EngineeringFaculty of Engineering & Information Technology

Overview

• Sustainability & Infrastructure– An Engineer’s perspective

• Current Challenges• Identifying Threats and

Managing Risks • New Developments and

Opportunities

Sustainability

• Broadly, is the ability to maintain a certain process or state, usually with respect to biological or human systems

• Human sustainability has become increasingly associated with the integration of economic, social and environmental spheres

• Involves “meeting the needs of the present without compromising the ability of future generations to meet their own needs” World Commission on Environment and Development (Brundtland Commission) – Report to UNGA 1987

Sustainability requires a radical shift in thinking

Radical transformation of the infrastructure that supports life on the planet is needed if we are to attain a sustainable future(from Peter Head - Brunel Lecture 2009)

Evolution of the Ages

• Stone Age• Industrial Age• Information Age• Ecological Age

(CO – 80%)2

1.44 gha / CapitaEcological Footprint

HDI Increase Human Development

= 2050 Ecological Age

(from Peter Head - Brunel Lecture 2009)

Human Development Index

HDI is a comparative measure of life expectancy, literacy, education and standards of living for countries world wide

(Peter Bowtell – ARUP)

Our Shrinking Earth

19007.91

19505.15

19872.60

20052.02

20301.69

20501.44

Hectares of Land Per Capita

(from Peter Head - Brunel Lecture 2009 & NSW State of the Environment report 2006)

Greater Sydney - 6.18

Sustainability & Economics

• Since Industrial Revolution most Economic systems are based on growth

• Growth = Prosperity• Growth = Consume• Now being confronted:

– Limits to growth– Limits to resources– Limits to consumption– Limits to environment

Source: NOAH / NASA

Energy Consumption

(Peter Bowtell – ARUP)11

The CO2 footprint of transport

12(from Peter Head - Brunel Lecture 2009;Quoted from Kenworthy - 2003)

Sydney

Getting the Balance Right

• Sustainability: improving the quality of human life while living within the carrying capacity of supporting eco-systems

• More recently “Triple Bottom line” approach:– commercially viable development – enhance community wellbeing – environmental renewability and

conservation of resources • Objective of balancing these is “Sustainability”

bearable equitable

viable

sustainable

Triple Bottom Line Philosophy

Adams, W.M. (2006) "The Future of Sustainability: Re-thinking Environment and Development in the Twenty-first Century”

Balancing the spheres of influence

Social

EconomicEnvironment

Sustainability and Infrastructure

• Economic growth understood as New = Good

• Political Drivers– New projects = success– No votes in maintenance

• Educational Drivers– Engineers trained to design

new, not sustain existing• Decisions based on

traditional economic models, rather than sustainability principles

Infrastructure Challenges

• “Infrastructure Australia” an excellent initiative– Highlighted problems with planning – Prioritisation and best value / national interest– Aims to improve decision making processes

• However, the focus still appears to be on “new” projects, rather than how we can improve / maintain existing infrastructure

• Need for a change in mind-set and new economic / decision making models if we are to develop sustainable practices

Infrastructure Challenges

• Declining state of existing infrastructure is evidenced by the Australian Report Cards (IEAust & GHD)

– civil infrastructure is barely adequate or poor– similar situation in US (refer Civil Engineers Aust - Feb 2009)

– e.g: 1 in 4 bridges either deficient or obsolete• Private investment focuses on new projects

rather than maintaining existing infrastructure– we actually need to get the mix right for BOTH!

• The Great Challenge of “Aging Infrastructure” Priority: “Restore and Improve Urban Infrastructure” Nat. Academy of Eng. (July

(IEAust Infrastructure Report Card NSW 2010)

IEAust Score Sheet – NSW 2010

Key Recommendations:• long-term infrastructure vision and plan• greater attention to managing demand for

infrastructure services, rather than relying on building new infrastructure to meet demand

• factor in the impact of climate change • cooperation and collaboration between all

levels of government and business • develop innovative funding models to maintain

and provide the required infrastructure19(IEAust Infrastructure Report Card NSW 2010)

Government Challenges

Funding tensions:Maintain existing?Upgrade / improve existing?Build new?

Government Challenges

Funding tensions:Maintain existing?Upgrade / improve existing?Build new?

Need for a change in mind-set

• OECD: sustainable infrastructure (structures) requires 3% of the asset replacement value be budgeted each year for maintenance (on average)OECD Road Transport Research – Bridges (1992) / OUTLOOK 2000 (1999)

• Obviously this varies with age and use – new assets would require less, older ones more

• Expenditure in Australia varies between less than 0.5% and 1.5% depending on the asset owner (ave. for State Governments approx 1.2%; less in LG)

• This lack of adequate funding creates a cycle of obsolescence

Degradation of Infrastructure

• “Normal” wear and tear• Biological / Chemical / Environmental hazards• Increased frequency of use (e.g. more traffic / demand)

• Increased magnitude / severity of “load”– e.g. increasing axle loads from 8t to10t

increases the damage potential by 145%– 10% increase every 10yrs– Extreme natural events– Climate change

Degradation is caused by one or more of:

ATSE Report “Assessment of Impact of Climate Change on Australia’s Infrastructure” (2008)

Infrastructure Degradation

• Detail / construct for durability

• Resource adequately• Correctly identify

damage• Understand its impact• Intervene effectively

– Maintenance– Repairs– Strengthen / Optimise

Degradation increases with failure to:

Source: Aboura et al – UTS / RTA (2008)

Some Examples of the Challenges facing our cities

I-35W Mississippi River Bridge

• An eight-lane, steel truss arch bridge that carried I-35W across the Mississippi River in Minneapolis, Minnesota

• During the evening rush hour on August 1, 2007, it suddenly collapsed, killing 13 people and injuring 145

• The bridge was Minnesota's fifth busiest carrying 140,000 vehicles daily

• Opened to traffic in 1967, inspected annually by Minnesota DOT, but not in 2007

(NTSB photo)

What caused failure?

• Investigation by the National Transportation Safety Board & FHWA research centre

• Jan 15, 2008, the NTSB announced they had determined that the bridge's design specified steel gusset plates that were undersized and inadequate to support the intended load of the bridge which had increased over time

• Nov 13, 2008, the NTSB released the final findings of its investigation

Photos - NTSB

Localised plate buckling

What caused failure?

• The primary causes were:– under-sized gusset plates for modern loads– additional load from 51 mm of concrete (road

surface) increasing the dead load by 20%. – extraordinary weight of construction equipment

and materials (262 t) on the bridge just above its weakest point at the time of the collapse.

– inadequate inspection procedures.– corrosion was not the significant factor, but it

had contributed to some weakening & cracks.

Proactive Asset Management- Lessons Learnt

Understanding the condition of the asset needs investment and involves:

• Developing effective assessment systems for quantifying safe capacity / acceptable performance

• Identifying where the greatest needs / risks are located

• Using this information to develop and maintain an “information system” that permits strategic & cost effective interventions

• Essential for sustainable management of infrastructure

Extreme Loading EventsUrban Flooding

Photos – Courier Mail / AFP

Extreme Loading EventsCyclonic Winds

Photos – Paul Crock AFP

Earthquakes

Extreme Loading Events

Photos – Andy Buchanan

Sustaining Infrastructure

• The issue of aging infrastructure applies to all materials and all types of structures / assets

• The reality is that we cant afford to replace every piece of infrastructure

• Engineers have a professional and social responsibility to maintain the operational effectiveness and safety of infrastructure

• Both a challenge and an opportunity!• Illustrate - short focus on timber structures

Example:Timber Structures in Australia

• Historic applications• Current applications• Development of “tools”

that enable sustainable practices– damage detection– risk assessment– strategic maintenance– repair & rehabilitation

Timber has been an essential and integral part of rural Australia’s

buildings and infrastructure since early

European settlement

Many are still performing wellAfter 150+ years!

Yet, despite the fact they are often not well maintained

Structures such as these have been “out of sight, out of mind”

Similarly with bridges – an essential, but under valued part of our rural infrastructure

Multi-storey timber warehouses were common in the 1800’s - many have been recycled into offices

However, lack of understanding about detailing, maintenance and durability issues can lead to performance problems

Resulting in the need for expensive repairs!

Case Study: Sustaining Timber Bridges

• A main focus of R&D at UTS since 1990

• Collaborative with RTA, Industry, Local and Federal Governments

• Approx $5m of R&D projects

• Development of new technologies:– risk ID / assessment – repair & rehabilitation

Timber Bridges - Context

• Approx 40,000+ bridges in Australia• Approx. 27,000 are aging timber bridges

– most are girder / corbel (spans 8-10m) – some truss bridges (spanning up to 36m)

• Essential part of our transport infrastructure– mainly in rural areas / Local Government– most 70+ years old– designed for 14 to 18t– now carrying 44t plus!

• Asset value in excess of $25B• An important part of our history

with social & cultural significance

Special Challenges withHeritage Structures• Heritage Legislation

means that many old bridges must be kept operational

• Tension between maintaining hist. integrity (size of members) and safety for current loads

• Significant R&D projects, consulting and training

• Development of new structural systems, design & detailing methods

Addressing the “guess work” in strength assessment of bridges….

One of the biggest problems has to do with the assumptions we make and conclusions we draw when we assess / model the bridge structure……

Uncertainties & Assumptions

• Reliable assessment requires accurate information about:

– Integrity of member sections (decay / corrosion / spalling)

– Load history and damage– Structural interactions – Material properties

(variability and aging effects)• Errors can be significant!• Overly conservative decisions also

can be costly!

How safe is safe?

Tools that Facilitate Sustainable Practicesto manage Infrastructure assets

New Technologies for Damage Detection

• Significant R&D on NDE technologies for determining the location and extent of “damage”

• The concept of “health monitoring”• Emerging Technologies (most promising):

– Dynamic / Modal Analysis– Radiography and GPR– Stress Wave techniques– Acoustic Emission

• Potential for a “quantum leap” in assessing the condition of existing structures

Dynamic / Modal Analysis

• New method developed by UTS in partnership with IPWEA / RTA

• Provide good “global” indication of safe response of superstructure

• Quick to perform and cost effective• Provides accurate information

about global behaviour of beam structures (timber, conc & steel)

Dynamic / Modal Analysis

• Next generation identifies location and size of damage (voids / loss of member integrity)

• Development of neural networks that enable the system to “learn”

• Linked with probabilistic strength models derived from testing

Ground Penetrating Radar

• Uses electromagnetic waves to generate an image of internal features

• Ideal for investigating objects with low conductivity such as masonry, concrete and timber

Source: W.Muller – QDMR (2008)

Ground Penetrating Radar

• Recent developments can create 3D images

• Can be used effectively with other NDE (e.g. thermal imaging)

Source: L. Binda – TU Milano (2008)

Ultrasonic Tomography

• Ultrasonic pulse velocity (UPV) used to create 2D and 3D images of internal voiding

• Data is analyzed in terms of propagation velocities and arrival of the transmitted ultrasonic pulse

Source: De La Haza et al - SFR (2008)

Acoustic Emission

• AE signals can identify micro-cracking mechanisms in reinforced concrete

• Applied to corrosion-induced cracks due to expansion of corrosion products

• Potentially effective for identifying / quantifying damage accumulation

Source: Ohtsu et al - SFR (2008)

Estimate of crack depth Image of water filled crack

Implementation Challenges

• Translating R&D into practice• Training professionals to

interpret and apply the results• What is the effect of damage

on structural performance?• Is it still safe?• What needs to be done?• How soon?

Client: How do I fix it?

Key Steps to Sustaining Infrastructure for our Cities

• Understand the asset, what is does, how it is performing and what is required to keep it safe

• Rate it’s value using “triple bottom line” criteria• Accurately assess and quantify it’s condition• Maintain and plan strategic interventions that

repair, rehabilitate or upgrade• Develop tools and techniques for “sustaining”

rather than “replacing”• Fund accordingly

What have we learnt from all this?

Aging Infrastructure makes our cities vulnerable and fragile

• Our cities are more than buildings and physical infrastructure, yet they are totally dependent upon it

• Infrastructure is often hidden; a skeleton that provides a framework for the city eco-system

• Design and operation of our cities is a critical challenge to humanity in the 21st century

Urban – Rural crossover

Half the worlds population live in cities ... which are responsible for nearly 75% of the world’s greenhouse gas emissions

The Urban Challenges• Transport• Existing Buildings• Waste Management• Water• Energy Supply• Outdoor Lighting• Planning &Urban Land Use• Food & Urban Agriculture• ICT• Finance & Economy • Climate Adaptation

61http://www.arup.com/Publications/Climate_Action_in_Megacities.aspx

(source: Peter Bowtell ARUP - 2011)

Buildings account for:

• 38% total energy use • 65% electricity consumption• 30% CO2 emissions

A Paradigm Shift

Buildings are critical, renewability is essential:– Materials– Energy– Total Life Cycle

Potential of Timber in Buildings

• Timber has a role to play in infrastructure for cities

• Why?– Structurally efficient & reliable – Low process energy– Efficient carbon store– Recyclable & Sustainable– Relative ease of de-

construction– Renewable - we can grow more

• Overview existing uses• New timber technologies

ALL LOADS CARRIED BY TIMBER!

Normal “current” uses

Source: B Hutchings - TimberBuilt P/L (2008)

New Building Applications – Drivers for O/S developments

• “Green building” a is strong driver for use of timber overseas in terms of carbon store, process and operating energies and renewability

• Shift from individual dwellings to multi-functional precincts (multi-storey commercial & residential)

• New products with inherent sustainability (LCA)• Prefabricated Floor, Wall & Roof systems with

significant benefits for construction and de-construction / recycling

New Developments in Europe

7 storey building - Berlin

M-M Kaufmann Glulam & CLT

4 storey building - Munich

KLH - Austria

Up to 6 storeys – Switzerland

9 storey building - London

New Developments Overseas

Up to 6 storeys – Canada

Prototype Buildings

NMIT – Nelson NZ

Aurecon - Engineers, ISJ - Architects

Prototype Buildings

NMIT – Nelson NZWinner of the Institution of Structural Engineers UK’s Structural Awards 2011 in the health & education category

Sustainable Buildings

• Timber has a role to play as a sustainable material for buildings in the Ecological Age

• Designing for “whole of life” value & worth

• Understanding sustainability processes

• Detailing & const. for durability• Creative use of new products

and processes

Conclusions:Sustainable Infrastructure

• Significant challenges facing Design Professionals, Planners and Government

• Urgent need to educate existing & future decision makers:

– Triple Bottom Line “sustainability” principles– Design of new structures incorporating “renewable” mat’s– Assessment, protection / enhancement of existing

• Need for us to provide leadership in the community – Understanding and communicating the need for change– Lobbying for appropriate resources– Using our skills & new technologies to create and

implement sustainable practices

Conclusions:Sustainable Infrastructure

• Aging infrastructure is a risk to our Cities that must be recognised and addressed

• How we manage existing and create new infrastructure must be informed by an ethos that is committed to the concept of sustainable precincts

New thinking is critical for the Economic, Environmental and Social aspects of Australia’s Infrastructure and Cities it supports, to become truly Sustainable. Creative leadership and the multidisciplinary skills of Designers, Planners & Decision makers are essential for this to occur.

thank you for your attention

http://www.youtube.com/watch?v=WRwA291NAuM&feature=youtu.be

Lifetime CO2 emissions

One building, four designs

Concrete Steel Timber TimberPlus

Sequestered

Operational

Transport

Maintenance

Embodied

Operational energy > embodied energy

Embodied CO2

Aluminium

Concrete

Overall CO2 emissions

Carbon Neutral for Timber

Negative for TimberPlus

utspeaks: our fragile cities (part 1: keith crews)

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