T.Y. Lin Lecture
Bridge maintenance, renovation and management - R&D governmental program in Japan
YOKOHAMA NATIONAL UNIVERSITY, YOKOHAMA, JAPAN
The collapse of Sasago Tunnel located on the Chuo Expressway about 80 kilometers west of Tokyo in 2012 has led to doubts about the current quality and safety of infrastructure, and immediately brought public attention to the issue of infrastructure degradation in Japan. Japanese government decided to invest on research and development for efficient management of infrastructure through implementation of science and advanced technology. The emphasis is placed on bridges. The new R&D program named “Infrastructure maintenance, renovation and management” is started in 2014 under the Council of Science, Technology and Innovation (CSTI)‘s Strategic Innovation Program (SIP). The 5-years program covers various subjects of infrastructure maintenance with key technologies in condition assessment using non-destructive testing, monitoring and robotics; long-term performance prediction of infrastructure, development of durable high-quality of material for repair and replacement, and management of large amount of bridges and other infrastructure data using advanced information and communication technologies (ICT). The program consists of about 60 research projects involving universities, government research institutes and industries. This initiative is expected to prevent further accidents and setting an example for efficient bridge and infrastructure maintenance by reducing the burden of maintenance works and cost. In the lecture, outline and major output of this SIP program are explained.
LIFE-CYCLE RELIABILITY OF BRIDGES UNDER INDEPENDENT AND INTERACTING HAZARDS
Waseda University, Tokyo, Japan
DAN M. FRANGOPOL
LEHIGH UNIVERSITY, PA, USA
Field investigations after recent large earthquakes confirmed that several bridges were severely damaged and collapsed not only due to the earthquake, as an independent hazard, but also to the subsequent tsunami or landslide. Therefore, it is important to study both independent and interacting hazards and their effect on bridge reliability. Although earthquake is still a dominant hazard to structures in many earthquake-prone countries, a life-cycle reliability approach has to consider both independent and interrelated hazards causing bridge failure. Such an approach is presented in this keynote paper. In addition, issues related to life-cycle analysis, design, risk, resilience and management of bridges under earthquake and other hazards are discussed. Finally, the concepts and methods presented are illustrated on both single bridges and bridge networks.
Assessment of the dynamic behaviour of railway bridges for high-speed traffic
University of Porto, Porto, Portugal
In railway bridges the dynamic effects induced by high speed traffic can be very significant due to the rapid rate of loading, the passage of successive loads with uniform spacing which can create resonance and the variations in wheel loads resulting from track irregularities. Transitions to railway bridges are zones where significant dynamic effects also occur due to the rapid degradation of the track, mostly due to the development of settlements in the backfill.
The assessment of these dynamic effects is of the utmost importance because excessive vibrations and deformations can endanger traffic by creating unacceptable changes in track geometry, can lead to fatigue damage of the structure, ballast instability, unacceptable reductions in wheel-rail contact forces and create conditions which cause passenger discomfort.
The dynamic effects induced by the simultaneous action of traffic and wind or earthquakes loads should also be considered in some scenarios. To make a rigorous analysis of the dynamic behavior of railway bridges methodologies for 3D analysis of the train-track-structure dynamic interaction, developed by the centre of competence in railways of the Faculty of Engineering of the University of Porto (CSF-FEUP), are described. View more.
Dynamic models of the track and forms of modelling of the track irregularities are described. Dynamic models for high-speed trains, including validation based on dynamic tests, are presented. A review of the most recent criteria for the assessment of structure fatigue damage, track stability, wheel-rail contact stability and passenger comfort, is also made.
Subsequently, several case studies developed by CSF-FEUP are presented, showing the efficiency and the usefulness of the developed methodologies and enabling the achievement of different objectives, such as:
- The experimental validation of dynamic models of the train-track-structure system;
- The running safety assessment of trains moving over long bridges subjected to earthquake or wind actions;
- The track stability and wheel-rail contact stability safety assessment on short span railway bridges;
- The fatigue damage assessment of precast and composite railway bridges;
- The running safety assessment of trains for settlement of the backfill at transition zones to railway bridges.
A Vision for Vision-based Technologies for Bridge Health Monitoring
UNIVERSITY OF CENTRAL FLORIDA, ORLANDO, FL, USA
Condition assessment of bridges evolved over the years with the advances in non-destructive evalua-tion technologies, field tests and structural health monitoring. As a result, technological advances changed the resources that bridge engineers can tap intol; however, the requirement for practical, low-cost and effective approaches has remained the same. The writer and his research team have ex-plored vision-based technologies to fulfill such re-quirements. In this paper, first the vision-based tech-nologies will be presented along with capabilities and limitations. It is also important to recognize that the views of different stakeholders in terms of their needs and expectations from non-destructive evalua-tion and structural health monitoring technologies show variations. In the second part of the paper, re-sults from a survey study are presented based on communications and interviews with infrastructure owners and engineers working in the area of inspec-tions, maintenance and decision-making. Finally, some solutions and example applications will be pre-sented with particular emphasis on the use of vision-based technologies while addressing the needs iden-tified through the survey.
The engineering and management of major steel box girder bridges; lessons from West Gate Bridge.
COWI, London, United Kingdom
Steel box girders provide an efficient and eco-nomic solution for long span bridges, and are fre-quently used for more modest spans as well. Their behaviour and design are now well understood, and when properly detailed and constructed, with well-conceived operation and maintenance plans in place from the outset, modern steel box girder bridges also provide good long term solutions with low whole-of-life costs. Early examples of such structures from the 1960's tended to suffer due to insufficient under-standing of design or maintenance issues or because of poor attention to detail. In addition, the enormous increase in traffic since then has placed an extra de-mand on these structures, which was not envisaged at the time of their design. As a result several have subsequently undergone substantial refurbishment and repair.
Many lessons have been learnt by those involved with these old structures over the years, and these lessons have informed and thereby improved the de-sign, construction and maintenance of modern steel box girder bridges. The author has spent most of his working life engaged with such structures and he will draw on that experience to illustrate these im-portant lessons. View more.
Ten years ago, the West Gate Bridge in Mel-bourne was substantially strengthened and upgraded to accommodate an extra traffic lane in each direc-tion and to deal with a variety of problems that had arisen since its construction. The project has received numerous high profile awards recognising its out-standing engineering achievement, including the Su-preme Award of the Institution of Structural Engi-neers in 2012. Ongoing maintenance includes inspec-tion, monitoring and repair activities which are fo-cussed on those areas known to be the most suscep-tible or most critical to the long term integrity of the bridge.
This paper describes the work involved in the strengthening, refurbishment and ongoing mainte-nance of the steel box girder cable stayed bridge, and touches on the wider lessons learnt from other similar major bridge structures.
It is nearly 50 years since the tragic collapse dur-ing construction on 15th October 1970, and the ram-ifications of that event still reverberate today. The lessons learnt from that catastrophe and other steel box girder collapses at around that time have had a profound impact on steel bridge design worldwide, and it is important that bridge engineers and manag-ers are fully aware of the implications so as to avoid any possibility of the same thing happening again. This paper touches on those lessons and how they have influenced the design, construction and man-agement of steel box girder structures today.
The paper addresses important issues of interna-tional relevance and is aimed primarily at engineers, constructors and owners of large bridges faced with the challenge of extending the lifespan of existing structures.
Managing Existing Bridges – On the Brink of an Exciting Future
INFRASTRUCTURE MANAGEMENT CONSULTANTS GMBH, ZÜRICH, SWITZERLAND
In course of bridge design and construction, computational models are developed, by means of which behavior of newly constructed bridges exposed to various combined actions can be determined. Relevant combinations of these actions are referred in Eurocode as design situations, against which the safety and serviceability of bridges are checked. The wealth of information acquired on each specific bridge during the design and construction is currently not being exploited effectively during the service life of these bridges. After the reception of newly designed bridge this information is handed over to the bridges’ owners or operators that act further on as their trustees. However, in most cases they don’t have tools and resources to use this information efficiently. During the service life, the owners and/or operators are bound to monitor the condition of bridges and their ability to perform as required. To this end inspections are performed that document observable changes from as-new condition. It is a common practice to evaluate condition state of a bridge and/or its elements qualitatively using an ordinal scale. The condition state expresses a vague measure for the deviation of inspected bridge from “as new” condition that is, at best, loosely correlated to safety and serviceability. If this vague measure reaches some threshold further investigation can be triggered that build upon the models – if these are still available - developed during the design and construction. Even if the models are available the effort to understand and restore all necessary information may be substantial. If the documentation of a bridges is lost or is of insufficient quality, the assessment effort may reach the one of the original design. View more.
Smart combination of increasingly sophisticated Bridge Management Systems, Bridge Information Models and Structural Health Monitoring has a potential to bring bridge management to a completely new level. The future Bridge Management System (fBMS) are to be based upon semantically rich Bridge Information Models that entail a suitable geometry of a bridge together with material properties and structural systems. Observations during inspections as well as monitoring data can be directly introduced in fBMS and allow effective updating of safety and serviceability. If embedded in a Geographical Information System, simulation of hazard situation can be performed that would allow contingency planning in case of extreme events. Finally, these models can be useful as a part of an early warning system during the unfolding of extreme events.
Clearly, the owners and/or operators must provide both financial and personal resources to maintain a fBMS and its data. Owners need in-house competence both in structural and decision engineering similar to the banking sector, where competence in financial and decision engineering is required. It is not a coincidence that in both sectors the term “Asset Management” is widely used.
The lecture will give a sneak preview into this exciting future management of existing bridges, which at least in the research arena has been already launched.
Timber bridges in Australia: where to from here?
Aurecon, NSW, Australia
There is estimated to be approximately 5,000 timber road bridges in Australia today. The majority were constructed in the 19th century as simple girder bridges with spans up to around 10-12m. Bridge lengths varied from single spans up to viaducts several kilometres in length. The bridges utilised Australia’s then plentiful supply of exceptional quality hardwood which could generally be sought close to the bridge site.
These bridges have invariably been extensively repaired and refurbished over time. This work has generally comprised like for like replacement of timber members such as girders, corbels, decking and sheeting and repairing timber piles with new spliced sections or new pile caps supported on new timber, steel or concrete piles.
A substantial number of timber bridges are now starting to fall into disrepair. This is particularly so for the timber owned by local government. An example of this is in NSW a recent survey indicates there are over 400 local government owned timber bridges are in poor condition. There has been a number of reasons for this; substantial reduction in the availability of large timber sizes of the strength grade required for timber bridges, a real shortage of workers skilled in the construction and repair of timber bridges, a lack of funding available for the repair of the bridges and, until recently, a Design Standard applicable for the design of timber bridges. View more.
A general review is made of the general state of local government owned timber road bridges in Australia today. This comprises a review of the condition of the bridges, and the rate of deterioration. Replacement options are discussed. Some replacement options are reviewed with reference to construction and maintenance costs, speed of construction and sustainability. Conclusions are drawn to with an attempt to enable relevance in global locations outside the Australian context.
The author is chairman of Australian Standards Committee BD090-08, responsible for the technical input to the new bridge design standard, AS 5100.8 “Bridge Rehabilitation and Strengthening”. This is the first Australian Design Standard to address the rehabilitation of timber bridges. This paper also draws on the learnings from the development of this Standard to look at the next generation of codes and standards covering rehabilitation and strengthening of timber bridges.
Innovative and sustainable operation and maintenance of bridges
Jens Sandager Jensen
COWI A/S, Kongens Lyngby, Denmark
How can learnings from innovative and sustainable operation and maintenance (O&M) of bridges con-tribute to improved planning for and design of bridg-es? The present paper will highlight how important it is to consider O&M issues already in the planning and design phase. Easy access for inspection, repair and renewal projects together with considerations regard-ing necessary traffic regulating measures are vital to cost optimal operation. Likewise, asset management systems that are able to provide precise and current performance information are vital to cost optimal op-eration.
Today's society demands solutions that maximise reliability and availability as well as minimise costs, environmental impacts and the probability of loss of life and limb. To accommodate this it is important both to take into account experience from O&M and the possibilities that comes with new technologies.
This comprise corrosion protection strategies that takes into account durability (service life models), ac-cess and O&M instructions for the bridge manage-ment. Durability shall be ensured through a design with the right material specifications, proper drainage details etc. as well as high quality execution. Further-more, service life models shall be robust and trans-parent so that they may be verified during operation and updated in order to reflect current performance. This argument is valid for a great number of compo-nents, where hands-on knowledge on long-term per-formance is a key to successful planning. Asset man-agement systems should be able to provide these long-term performance data in a structured and transparent way. This also allows for extrapolation of data within a portfolio of bridges. View more.
The principle of Building Information Modelling System (BIMS) is used in modern asset management systems to manage all stages of new infrastructure projects, i.e. design, construction and operation. Many bridge owners would like to use this technology for existing bridges also. The first step would be to estab-lish a 3-D model. Often a combination of scanning and imagery has proved successful. In this way own-ers move from "dead" data in paper records to "live" and fully digital data based on the principle of BIMS, which can be used in asset management.
Major bridges calls for bridge specific O&M man-uals. They will provide the necessary basis for safe and cost optimal O&M for such a large investment by the society. A lean Structural Health Monitoring Sys-tem (SHMS) is also a vital component for a major bridge as a mean for obtaining data describing the ex-posure conditions and performance of the structure.
A systematic identification of Life Cycle Costs fa-cilitates a holistic approach to cost optimal design. Similar to current O&M planning this could include user costs (delays etc.) and possible sustainability in-dicators.
Finally, application of risk analyses in design as well as during O&M has proven beneficial. In this way, the likelihood or occurrence rate is considered alongside the consequence. One example is bridge-specific Operational Risk Analyses (ORA) that have been performed for many existing major bridges. Of-ten they recommend risk mitigating measures such as fire protection of main cables, improved drainage and strengthening of barriers and railings. ORA's are re-viewed and updated on a regular basis, say every 10th year, or when significant accidents occur. Also, risk review, risk assessment and risk management is used when hidden defects in existing bridges are investigat-ed.
ETSI Project, 2013, Bridge Life Cycle Optimization Stage 3, http://etsi.aalto.fi/Etsi3/PDF/Reports/ETSI_Stage3.pdf
CIRIA C764, 2017, Hidden defects in bridges – guidance for detection and management, ISBN 978-0-86017-779-1
COST TU1406, Quality specifications for roadway bridges, standardization at a European level, www.tu1406.eu
Jensen, J. S., 2010, Cable supported bridges – design, mainte-nance, rehabilitation, and management, IABMAS 2010.
Jensen, J. S., 2016, Trends within Sustainable Bridge Operation and Maintenance, IABSE 2016
Linneberg et al, 2013, Optimising inspection and maintenance using risk and reliability.
Linneberg, P. et al, 2014 Challenges within Life Cycle Cost (LCC) Studies and Life Cycle Assessment (LCA), IABMAS 2014.
MAINLINE, 2013, MAINtenance, renewaL, and Improve-ment of rail transport iNfrastructure to reduce Economic and environmental impacts, www.mainline-project.eu
Value of monitoring data for long-span bridge operation – Aerodynamic point of view
Seoul National University, Seoul, Korea
Structural health monitoring (SHM) systems are commonly used in most long-span bridges. Although a lot of data are being accumulated from various sensors, there are relatively few examples the monitored data are used directly in bridge operation judgment and decision making. In this study, the author will share case studies using the monitoring data in the process of identifying incidents, finding causes and countermeasures that have been experienced in long-span bridges in operation over the past several years. The reviewed cases are the vortex oscillations observed in two cable-supported bridges, the estimation of the damping ratio through operational modal analysis in the cause identification process, and the rollover accident during strong winds experienced in another bridge. Since all the cases were caused by wind, wind speed data as well as wind tunnel test results were used together. The data used were simple and basic ones, such as the measured acceleration and wind speed data, but the author reports on ways to increase the value of data by using data analysis techniques such as system identification, wind tunnel test, and artificial neural network. As a result, the author would like to propose the damping characteristics of flexible bridges from the long-term measurement data and the strategic vehicle traffic control plan during strong winds.
DESIGN CONCEPT OF THE TWIN RIVER BRIDGES IN CHONGQING, CHINA
TY LIN INTERNATIONAL, SAN FRANCISCO, CA, USA
The metropolitan area of Chongqing is bisected by two rivers, the Yangtze and the Jialing, into three parts: Nanan in the south, Yuzhong in the middle and Jiangbei in the north. The Twin River Bridges is a pair of cable supported girder bridges: the Dongshuimen Bridge crosses the Yangtze River from Nanan to Yuzhong, while the Qianximen Bridge crosses the Jialing River from Yuzhong to Jiangbei. The two bridges are also connected by a tunnel under the entire Yuzhong District. The area is the most visible location of the city so aesthetics was the most important aspect in the design. The bridges carry four lanes of city traffic and two tracks of rapid transit which has very stringent design requirements. The bridges are designed based on the concept of partially cable-supported girder bridge. This paper describes the development of two alternative design concepts proposed and the final construction of this pair of bridges.
- Key Dates
- Call for Abstracts Closed
- Registration Open November 2017
- Notification of Acceptance of Abstract 15 September 2017
- Full Paper Submission open 15 September 2017
- Full Paper Final Submission Deadline 17 November 2017
- Notification of Full Paper acceptance 18 December 2017
- Final Paper Submission12 January 2018
- Early bird Registration closes 2 March 2018
- Conference 9-13 July 2018
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