an integrated lifetime management system for civil ... · tt5-243, an integrated lifetime...

10DBMC International Conference On Durability of Building Materials and Components LYON [France] 17-20 April 2005

An Integrated Lifetime Management System for Civil Infrastructures

Ayaho Miyamoto Dept. of Computer & Systems Eng., Yamaguchi University, 2-16-1, Tokiwa-dai, Ube 755-8611, Japan e-mail: [email protected] TT5-243

ABSTRACT In our country, because there are a huge number of civil infrastructure systems, it will be becoming a major social concern to develop an integrated lifetime management system for such infrastructures in the near future. Then we need to develop an innovative system for long-term lifetime management engineering as Doctor for Infrastructure Systems. Namely, it needs to develop an integrated lifetime management system for civil infrastructure systems combined with the latest information processing technologies and intelligent health monitoring techniques, and also to establish the Doctor Degree for Civil Infrastructure Systems (INFRADOCTOR). This paper describes our Japanese strategy of life-cycle management in civil infrastructure systems for the 21st Century as a Center of Excellence (COE) Project in Japan. KEYWORDS Civil infrastructure, Integrated lifetime management, Health monitoring, Information technology, Prestressed concrete (PC) bridge.

10DBMC International Conference on Durability of Building Materials and Components LYON [France] 17-20 April 2005

TT5-243, An integrated lifetime management system for civil infrastructures, A. Miyamoto

1 INTRODUCTION Our country, Japan is now a country with highly developed social infrastructures in both qualitative and quantitative terms. They include urban expressway networks and other social facilities and such structures as bridges, dams, tunnels, etc. It will therefore be necessary as in Europe and the United States to maintain the service life (performance & structural function) of social stock as long as possible and take appropriate measures as it ages, in harmony with the natural environment [Miyamoto & Frangopol [2002]]. The process is generally referred to as maintenance. Engineers equipped with state-of-the-art information technology need to be developed to work as doctors diagnosing (evaluating and assessing) and treating (repairing and strengthening) structures including prestressed concrete (PC) bridges, that is establishment of diagnostics. A world standard computer system must also be developed that supports engineers and helps them inherit knowledge and experience because maintenance requires large amounts of knowledge and experience. PC structures are larger and often need to work longer, more than 100 years, than non-engineering products. They are subjected to diverse types of deterioration mechanism such as corrosion, fatigue, carbonation, alkali-aggregate reaction, etc. Detecting deterioration and deformation as early as possible for maintenance may require health monitoring equivalent to in-home medical care services for humans. This paper introduces a concept of strategic capital stock management (integrated life-cycle management system) (see Figure 1) and presents a management system that was developed for a PC bridge [Miyamoto [2002]; Miwa [2001]] as a specific example. The life-cycle management system incorporates life-cycle cost (LCC) and the concepts and analysis methods for management into the field of maintenance that used to be considered somewhat low-key as compared with the construction of structures. The system is an organic integration of studies in a wide range of academic fields including systems, electrical and mechanical engineering fields beyond the scope of civil engineering field. It is an environmentally friendly system aided by state-of-the-art information technologies such as network-based databases systems, multimedia virtual reality, intelligent monitoring, artificial life and artificial intelligence. 2 HEALTH MONITORING AND MANAGEMENT USING

INFORMATION TECHNOLOGY (IT) For example, it will be focusing on prestressed concrete (PC) structures including PC bridges, PC structures are more effective than reinforced concrete (RC) structures because prestressing the cross section of a member eliminates an unfavorable stress condition that is created by external forces and thus enables an effective use of the total cross section. If the tensile stress in any given cross section of a concrete member is controlled so as not to cause surface cracking under any combination of predictable external forces (as concrete is generally weak in tension stress), it is possible to construct a structure that requires minimum maintenance in the future. Then, it is generally say that cracking or other types of damage to concrete surface of a PC structure designed based on the above assumption therefore implies that the durability of the member has already been lost. To introduce of prestressing in all parts of a PC structure is, however, actually impossible. Especially, prestressing is often difficult at joints in cast-in-place backfill, in the longitudinal direction of a bridge slab, or at the anchorage of prestressing steel, then, reinforced concrete (RC) is used in some parts. In view of the above, "preventive maintenance" rather than "corrective maintenance" is expected to be generally adopted for PC bridges. In "corrective maintenance", which was used for RC structures in most cases, maintenance is carried out only after deterioration and damage become apparent in daily and regular inspections. In "preventive maintenance", decisions are made for maintenance using a health monitoring system that monitors time-based change in structural behavior with sensors installed on major structural elements including prestressing tendons. The latter approach overlaps the concept of performance-based design, which has recently been applied worldwide.



Figure 1. Technological components for building an integrated life-cycle management system.

Sensors

Integrated Internet Integrated Internet Monitoring SystemMonitoring System

Internet Virtual Internet Virtual Reality SystemReality System

Integrated Lifetime Integrated Lifetime Management System for Management System for Infrastructure SystemsInfrastructure Systems

MultiMulti--media Virtual media Virtual Reality Education SystemReality Education System

Environmental Environmental Impact Analysis Impact Analysis

SystemSystem

Natural Disaster Natural Disaster Risk Management Risk Management

SystemSystem

LifeLife--cycle Costs cycle Costs Analysis SystemAnalysis System

Structure Inspection Structure Inspection Support SystemSupport System

Intelligent Sensors Intelligent Sensors

WorldWorld--standard standard DataData--base Systembase System

Database for repa ir Database for repa ir /s trengthening /s trengthening

materialsmaterials

Database for repairDatabase for repair/strengthening /strengthening

methodsmethods

Database of Database of inspection inspection

resultsresults

Database of the Database of the history on repair/ history on repair/

strengthening worksstrengthening works

Performance evaluation

Performance Performance evaluationevaluation

Inventory data for Inventory data for infrastructure infrastructure

sys temssystems

Optimal maintenance planning

Optimal maintenance Optimal maintenance planningplanning


materialsmaterials


materialsmaterials


methodsmethods


methodsmethods


resultsresults


resultsresults








sys temssystems


sys temssystems





Figure 2 shows the position and role of the "integrated health monitoring system" in maintenance. The system enables real-time monitoring, a technological component for building an integrated life-cycle management system for PC and other structures (Figure 1). The "integrated health monitoring system" is composed of the Internet and other types of information technology, state-of-the-art information processing technologies and soft computing technologies. Figure 2 shows a flowchart of steps ((1)-(10) in Figure 2) that enable various interactive checking not only during design and construction but also during service. Monitoring (steps 6 through 10) is added to the conventional phases of design and construction of a structure (steps 1 through 5) [Smith [2001]]. The figure presents a correlation among three levels of behavior of the structure: required behavior (performance) Brequired, predicted behavior Bpredicted and measured behavior Bmeasured. S indicates the structure. In conventional design, functional (performance) requirements for the structure submitted by the owner are initially defined (step 1). Design is developed based on the comprehensive structural data obtained (step 2) and the behavior of the structure is predicted using an analytical model (step 3). After verifying (assessing) the performance requirements according to the prediction (step 4), construction is carried out (step 5). The completed structure is put into service. If the structure proves unsatisfactory as a result of performance verification, work (design) is carried out again from step 2 or 3. The steps are one-directional and lack a viewpoint of post-construction maintenance. Adding the monitoring phase represented as steps 6 through 10 in Figure 2 enables the monitoring of a third behavior (Bmeasured), which can be employed for improving the analytical model during design, the re-verification of performance requirements and the long-term checking. For efficient maintenance, the integration of large quantities of element technologies that have been accumulated for newly constructed structures and the aggregation of knowledge and experience concerning maintenance are essential. To that end, a system should be established to continuously hand down the knowledge and experience related to maintenance, and to conduct comprehensive training of next generation engineers while aiming to develop a world standard (Figure 1). In life-cycle management of diverse social capital stock, the maintenance of a PC bridge for example, appropriate diagnosis and development of a maintenance plan compatible with environmental considerations are

FormulationMonitoring

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BpredictedBpredicted

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� Evaluation

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Sas-builtSas-built� Construction

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Figure 2. Tasks of health monitoring in maintenance of a structure.

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FF Sas-designedSas-designed

BpredictedBpredicted

�Synthesis

� Evaluation

�Analysis

Sas-builtSas-built� Construction

BmeasuredBmeasured

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Performance

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F-FunctionB-BehaviourS-Structure

Figure 2. Tasks of health monitoring in maintenance of a structure.



important. Sharing knowledge and experience requires the development of a knowledge and experience dissemination system that exceeds time and space limitations. Image processing technologies and sophisticated multimedia virtual reality technologies are applied to represent in a short time frame the damage to and deterioration of social infrastructures that actually occur over a long period of time, and to substitute virtual experience for real experience. Figure 3 gives an image of an education system. It is a multimedia virtual reality system almost encompassing the world. It enables trainees to have a virtual experience of various damage conditions on a PC bridge or to virtually experience maintenance experts' thought process with respect to the points they focus on and how to arrive at a diagnosis based on the environmental conditions and the damage. 3 LCC BASED PC BRIDGE MANAGEMENT SYSTEM [Miwa [2001]] For the diagnosis of a PC bridge, preventive maintenance is generally adopted in combination with health monitoring because of the structural properties (see previous section) of such a bridge. Since reinforced concrete (RC) elements also constitute a PC bridge, corrective maintenance is also required for total maintenance of the bridge. This section describes a deterioration diagnosis system for PC bridges (BREX (Bridge Rating Expert System) for PC bridges). It is a feature of a bridge management system that is mainly intended for reinforced concrete bridges (J-BMS) that the author jointly developed. Figure 4 shows a flowchart of J-BMS steps for developing an optimum maintenance plan taking life-cycle cost into consideration [Smith [2001]]. Under J-BMS, a fundamental maintenance procedure is followed from inspection to diagnosis and remedial action. First, visual inspection or a similar level of inspection and detailed inspection are conducted in combination for existing bridges. Inspection results are stored in a database. The inspection data on the bridge to be diagnosed are extracted from the database and input to the "Concrete Bridge Rating Expert System" with the technical specifications

for the bridge. Then, the system (deterioration diagnosis feature) is activated. The load carrying

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European siteEuropean site

American siteAmerican site

East Asian siteEast Asian siteJapan siteJapan siteJapan site

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capability and durability of main girders and slabs of the bridge are rated on a 0-100 scale to indicate their soundness. Thus, the bridge is diagnosed and assessed. Next, future deterioration of the bridge is predicted using the "deterioration prediction feature" according to the soundness identified by diagnosis. Predicted progress of deterioration of members is visually verified. Finally, based on the progress of deterioration identified by the "deterioration prediction feature", the effects of remedial methods and the costs involved are assessed to deprive an optimum maintenance plan that specifies the selected method, timing of maintenance and life-cycle cost. This integrated management system focuses on existing concrete bridges. It enables not only the soundness diagnosis of existing concrete bridges and the selection of repair and strengthenig methods according to the diagnosis but also effective and efficient development of an optimum maintenance plan that produces the maximum effect within limited budgets. The system was constructed by applying such latest information processing technologies as neuro-fuzzy expert system, genetic algorithm (GA), and immune algorithm (IA) [Miyamoto [2002]].

Figure 3. Example of a system for transferring maintenance technology and knowledge based on multi-media virtual reality technology.

Discussed below are final diagnostic results for "8th -span of KS bridge", an eight-span post-tensioned prestressed concrete simply supported T-girder bridge in Yamaguchi prefecture. The results were obtained by inputting inspection data. Figure 5 shows part of the input screen for main girders and slabs. Dozens of parameters are input such as technical specifications for the bridge, various investigation and inspection results, and cracking conditions in slabs and main girders. Especially for PC bridges, results of inspection for deformations at the anchorage of longitudinal prestressing tendons, near the tendon sheath and at the anchorage of transverse prestressing tendons are also input to represent impacts on prestressing tendons (see Figure 5). Some parameters require multiple choice answers based on subjective judgements. Choices can be made at the click of a mouse. Figure 6 is a visual display of final diagnostic results reached by coupled calculation of diagnostic processes for PC bridges. The load carrying capability, durability and seaviceability of main girders and slabs of the bridge to be diagnosed are assessed on a 0-100 scale to identify their soundness. The results of comprehensive assessment of main girders and slabs can be displayed visually. Identifying the



Figure 4. Flowchart of steps under a J-BMS-based concrete bridge management system.

STARTSTART

·· Crack width·· Traffic conditions, etc.

Technical Technical specificationspecification

datadata·· Span of main girder: ? (m)Span of main girder: ? (m)·· Thickness of slab : ? (cm) Thickness of slab : ? (cm) ·· Type of structure : ?Type of structure : ?

Evaluation of performanceEvaluation of performance·· Load carrying capability, DurabilityLoad carrying capability, Durability·· Damage degree of bridge elementsDamage degree of bridge elements

Inspection dataInspection data

Flowchart of JFlowchart of J--BMSBMS

[ [ Concrete Bridge Rating Concrete Bridge Rating Expert System(Expert System(BREXBREX) ]) ]

Soundness Score : 0Soundness Score : 0--100100

Deterioration predictionDeterioration prediction

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Deterioration prediction curve

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Cost of Cost of maintenancemaintenance

·· Epoxy injection: ?UEpoxy injection: ?U·· Steel plate Steel plate

covering: ?Ucovering: ?U

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deterioration of prestressing tendons is most important on PC bridges. The screen therefore displays the results of deduction for assessing damage at the anchorage of prestressing tendons and along the tendon sheath to represent deterioration.

Figure 5. Inspection result input screens for the main girder (left) and concrete slab (right) of an existing PC bridge.

Figure 6. Output screens for final results from PC bridge-BREX for the main girder (left) and concrete slab (right).

The "deterioration diagnosis feature" is equipped with capabilities of verifying diagnostic results obtained by BREX and of learning by neural network. Clicking the button, "Execute How function" will direct the user to a frame shown in Figure 7. The frame shows all the diagnostic processes developed for PC bridges on the left. It also presents in the upper right details about the diagnostic

Main girder-Input screen Concrete slab-Input screen

Data for target bridge Data for target bridge

Input date: Input date:

Bridge name: Bridge name:

Input data Input dataPage change Page change

8th-span of KS bridge 8th-span of KS bridge

Jan. Jan.(A.D.) (A.D.)

Expansion of cracking at the anchorage of longitudinal PC tendons

Maximum crack width at the anchorage of longitudinal PC tendons

Development of free lime at the anchorage of longitudinal PC tendons

Concrete spalling or exposure of reinforcement at the anchorage of longitudinal PC tendons

Rust stains at the anchorage of longitudinal PC tendons

Pop-out at the anchorage of transverse PC tendons

Rust stains at the anchorage of transverse PC tendons

Maximum crack width on the slab

Crack orientation throughout the slab

Development of free lime in an area of 0.1m2 or larger

Number or cracks at minimum spacing of less than 50 cm

Number or cracks at minimum spacing of 50 cm or larger

Input the maximum crack width (mm)

Number of locations with free lime of 0.1 m2 or larger

Number of locations with free lime of less than 0.1 m2

Number of locations with concrete spalling in a 0.1 m2 or larger area

Number of locations with concrete spalling in an area less than 0.1 m2

Number of locations with exposed reinforcement and concrete spalling in a 0.1 m2 or larger area

Number of locations with exposed reinforcement and concrete spalling in an area less than 0.1 m2

Number of locations with rust stains in a 0.1 m2 or larger area

Number of locations with rust stains in an area less than 0.1 m2

Number of locations with pop-out in an area less than 0.1 m2

Number of locations with pop-out in a 0.1 m2 or larger area




Honeycomb cracking

Bidirectional cracking

Unidirectional cracking

No cracking



BACK NEXT BACK NEXT

Main girder-Input screen Concrete slab-Input screen

Data for target bridge Data for target bridge



Input data Input dataPage change Page change


Jan. Jan.(A.D.) (A.D.)

Expansion of cracking at the anchorage of longitudinal PC tendons

Maximum crack width at the anchorage of longitudinal PC tendons

Development of free lime at the anchorage of longitudinal PC tendons

Concrete spalling or exposure of reinforcement at the anchorage of longitudinal PC tendons

Rust stains at the anchorage of longitudinal PC tendons

Pop-out at the anchorage of transverse PC tendons

Rust stains at the anchorage of transverse PC tendons

Maximum crack width on the slab

Crack orientation throughout the slab

Development of free lime in an area of 0.1m2 or larger

Number or cracks at minimum spacing of less than 50 cm

Number or cracks at minimum spacing of 50 cm or larger




Number of locations with concrete spalling in a 0.1 m2 or larger area

Number of locations with concrete spalling in an area less than 0.1 m2

Number of locations with exposed reinforcement and concrete spalling in a 0.1 m2 or larger area

Number of locations with exposed reinforcement and concrete spalling in an area less than 0.1 m2



Number of locations with pop-out in an area less than 0.1 m2

Number of locations with pop-out in a 0.1 m2 or larger area




Honeycomb cracking

Bidirectional cracking

Unidirectional cracking

No cracking



BACK NEXT BACK NEXT

Screen for final reasoning Screen for final reasoningData for target bridge Data for target bridge




Obtained date: Obtained date:

Final reasoning resultsFinal reasoning results Final reasoning resultsFinal reasoning resultsMain girder Concrete slab

How function How function

Judgment items Judgment itemsSoundness score Soundness score

Serviceability of main girder

Load carrying capa.ofmain girder

Durability of main girder

Design of main girder

Whole damage of main girder

Execution of main girder

Service condition of main girder

Damage at midspan part

Damage at 1/4 span part

Damage at anchorage part ofPC tendons (main girder)

Damage along tendon sheath

Whole damage of concrete slab

Execution of concrete slab

Service condition of concrete slab

Damage at center part of the slab

Damage in the backfill

Damage in other areas than the backfill

Damage of overhang part

Damage at anchorage partof transverse PC tendons

Deterioration of slab materials

Surface condition

Screen for final reasoning Screen for final reasoningData for target bridge Data for target bridge




Obtained date: Obtained date:

Final reasoning resultsFinal reasoning results Final reasoning resultsFinal reasoning resultsMain girder Concrete slab

How function How function

Judgment items Judgment itemsSoundness score Soundness score

Serviceability of main girder

Load carrying capa.ofmain girder

Durability of main girder

Design of main girder

Whole damage of main girder

Execution of main girder

Service condition of main girder

Damage at midspan part

Damage at 1/4 span part

Damage at anchorage part ofPC tendons (main girder)

Damage along tendon sheath

Whole damage of concrete slab

Execution of concrete slab

Service condition of concrete slab

Damage at center part of the slab

Damage in the backfill

Damage in other areas than the backfill

Damage of overhang part

Damage at anchorage partof transverse PC tendons

Deterioration of slab materials

Surface condition



processes for the item (damage to the anchorage of prestressing tendons on the girder in this example) for which the diagnostic results need to be verified (inspection items) and the relevant sets of production rules (if-then rules) ((i) damage to and rust stains on the anchorage of longitudinal prestressing tendons, (ii) appearence of free lime at the anchorage of prestressing tendons on the main girder and (iii) cracking in pattern (7)). Thus, it is easily verified how the rules are applied to deduce the final diagnostic results. Present shapes of membership functions are also provided in the lower right for the sets of production rules (i) through (iii). The objective is to enable the verification of knowledge base update (effects of learning) in the case of variance of the diagnostic result from "right answers" such as opinions of domain experts and experimental results. Thus, effective support is provided in communication between engineers and systems developers.

Figure 7. Screens for supporting final result verification and knowledge update.

4 CONCLUDING REMARKS In advanced countries in Europe and the United States, life-cycle management of social capital stock including prestressed concrete (PC) bridges and other social infrastructures has recently been gathering attention. An example is LIFETIME Thematic Network, an organization based in Finland that is now being launched by the European Union as an area-wide project [Technical Research Center of Finland et al. [2001]]. Another group led by the United States has also been accumulating expertise and know-how of its own. The First International Conference on Bridge Maintenance, Safety and Management was held in Spain in July 2002 [Casas et al. [2002]]. Thus, there has been a move, mainly among the countries with well-developed social capital, to establish a common global goal. It is important for Japan to establish an advanced management system in the relevant field ahead of the rest of the world in close coordination with the recent move and create a base for research that will enable Japan to lead the world. Figure 8 illustrates how database systems are shared by combining health monitoring and next generation information technologies, and how world standards for an integrated life-cycle management system are developed. If Japan becomes capable of taking the initiative in the age of world standard development for maintenance owing to active approach, the efficiency of maintenance of structures including PC bridges will be increased and the field of maintenance will become technically more challenging. In the future, it is expected to be important to attract young excellent engineers to the field of protection of aged structures, which is analogous to the care of elderly people, and to make the field more dynamic. The author would hope that this paper would be of some help in the future.

How function

Rust stains at the anchorage of transverse PC tendons Progress of free lime development at the anchorage of main girder Cracking in pattern (7) Soundness score

0.00-7.00:No problem0.00-7.00-14.00:Rust stains

developed7.00-14.00:Rust stains

developed considerably

Rust stains at the anchorage of transverse Progress of free lime development at the Cracking in pattern (7)

Rust stains developed considerably









Rust stains developed

Degree of corrosionDegree of free lime

Freezing and thawinBridge age<30.0>

Deterioration of main girMaximum crackExpansion of cr

Cracking in patterns Concrete spallinDevelopment of

Degree of free lime Degree of rust stains

Cracking in patterns

Degree of free lime Rust stains at the an

Maximum crackExpansion of cr

Concrete spallin

Development of

Damage along the tendon

Damage at anchorage ofDamage at 1/4 span part<Damage at midspan part<Abnormal deflection<1.0

Whole damage of main girderDesign of main girder<48.95

Load carrying capa.of main girder

Durability of slab<64.5>

Load carrying capa.of slab<71.91>

Serviceability of main girder<64.98>

Serviceability of slab<61.7>

How function

Rust stains at the anchorage of transverse PC tendons Progress of free lime development at the anchorage of main girder Cracking in pattern (7) Soundness score

0.00-7.00:No problem0.00-7.00-14.00:Rust stains

developed7.00-14.00:Rust stains

developed considerably

Rust stains at the anchorage of transverse Progress of free lime development at the Cracking in pattern (7)










Rust stains developed

Degree of corrosionDegree of free lime

Freezing and thawinBridge age<30.0>

Deterioration of main girMaximum crackExpansion of cr

Cracking in patterns Concrete spallinDevelopment of

Degree of free lime Degree of rust stains

Cracking in patterns

Degree of free lime Rust stains at the an

Maximum crackExpansion of cr

Concrete spallin

Development of

Damage along the tendon

Damage at anchorage ofDamage at 1/4 span part<Damage at midspan part<Abnormal deflection<1.0

Whole damage of main girderDesign of main girder<48.95

Load carrying capa.of main girder

Durability of slab<64.5>

Load carrying capa.of slab<71.91>

Serviceability of main girder<64.98>

Serviceability of slab<61.7>



Figure 8. Image of a world-standard-oriented integrated life-cycle management system. 5 REFERENCES Miyamoto, A., & Frangopol, D. A.(Ed) 2002, ‘Maintaining the Safety of Deteriorating Civil Infrastructures’, Practical Maintenance Engineering Institute of Yamaguchi Univ., Yamaguchi.

Miyamoto, A. 2002, ‘A Practical Bridge Management System for Existing Concrete Bridges’, Concrete Structures in the 21st Century(CD-ROM:C), fib2002 Osaka Congress, pp.111-120.

Miwa T. 2001, ‘A Software Tool for Developing Bridge Rating Expert System and Application to PC Bridge Assessment’, Master Thesis of Yamaguchi University, Yamaguchi.

Smith, I. F. C. 2001, ‘Increasing Knowledge of Structural Performance’, Structural Engineering International (SEI), IABSE, Vol. 11, No. 3, pp. 191-195.

Technical Research Centre of Finland & VTT Building and Transport, 2001, ‘Competitive and Sustainable Growth Programme’, LIFETIME Thematic Network, (HP address: https://www.rte.vtt.fi/QuickPlace/lifetime_public/Main.nsf).

Casas, J.R., Frangopol, D. A. and Nowak, A.S.(Ed) 2002, ‘Bridge Maintenance, Safety and Management’, International Center Numerical Methods in Engineering (CIMNE), Barcelona.

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