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9.Research on Life-Cycle Management of Infrastructure

Background and Objectives

There has been demand to secure the functions and performance of existing port and airport infrastructure above the required level, and to promote their beneficial use. Thus a management system consisting of inspection, diagnosis, evaluation, prediction and countermeasure techniques
should be developed to realize life cycle management (LCM) of the infrastructure. In this research, a series of research projects are implemented to establish and achieve the systematization of life cycle management, including durability enhancement of materials, prediction of structural performance degradation, countermeasures and repair techniques.

Research topics

The following three topics are focused on in this research theme.

  1. Integrating inspection and diagnostic techniques
    Improving the kinematic performance of the inspection (vehicle) was examined for integration and labor-saving of inspection and diagnosis of structures and materials in marine environments.New diagnostic techniques were investigated for inspecting structures and materials where many accumulated inspection results from real structures are analyzed through the probabilistic approach.
  2. Investigation of deterioration mechanisms and its prediction
    Deterioration mechanisms of materials constituting structures were investigated to establish prediction models of deterioration for each material. Also, the relationship between the recycling and life cycle of the materials was clarified to establish prediction and countermeasure techniques from material viewpoints. Deterioration process prediction under several exposure environments was also experimentally examined.
  3. Evaluation of structural performance degradation and quantification of a repair effect
    The evaluation models on structural performance degradation and performance recovery by repair were investigated by examining the mechanisms of structural performance degradation due to material deterioration.The evaluation scheme to quantify repair effects was examined by incorporating the NPV and LCC concepts for evaluation of the maintenance scenarios induced by the LCM system.

Activities in FY 2010

figure

figure
Monitoring of half-cell potentials of reinforcing steels in concrete of
superstructure of pier

In order to secure a performance higher than demanded for the existing structures and to use stocks effectively and for long periods, it is indispensable to establish an LCM system that integrates the techniques of inspection and diagnosis of structures, evaluation and prediction of structural performance, and repair and reinforcement. Especially in the current Mid-term Plan period, we focused on the study to practically apply the LCM system to berthing facilities.
To achieve practical application of the LCM system, our study in FY 2010 focused on: 1) enhancing the techniques of inspection and diagnosis, 2) predicting the performance degradation of structures and quantifying the effect of repair.
To achieve Objective 1 above, we considered whether and how nondestructive testing techniques can be utilized to perform highly accurate investigation, diagnosis and monitoring of port and harbour structures. Especially, we studied how to evaluate corrosion of reinforcing steel in concrete using nondestructive testing techniques. We monitored half-cell potentials of reinforcing steel in concrete at a pier superstructure as shown in the figure below and succeeded in nondestructively detecting steel corrosion. We also studied a new technology that allows noncontact measurement of stress distribution in structural members.
To achieve Objective 2 above, we estimated how a maintenance scenario that adopts structural details considering maintenance simplification and implements preventive maintenance is economical, based on the LCC trial calculation using the already-established LCM system for pier structures. To aim at expanding the application range of the established LCM system, we studied to develop the LCM system for sheet-pile-type and gravity-type quay walls.

Moreover, we held the "International Seminar on Strategic Maintenance of Port Facilities" (Kuala Lumpur, Malaysia, February 2011) to promote and utilize the LCM technology in ASEAN countries. We created “Guidelines on Strategic Maintenance for Port Structures” as an outcome of the
ASEAN-Japan Transport Partnership Projects and published the guidelines on our website. The guidelines provide the basic concept that should be followed when maintenance manuals for port structures are prepared in ASEAN countries and can be used as reference materials when port structures are inspected, diagnosed, repaired and reinforced in the countries.

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