3B. Research on Strategic Maintenance for Port and Airport Facilities

Background and Objectives

  • The development of strategic maintenance methods,based on advanced technologies of inspection and diagnosis,performance evaluation and prediction, and implementation of countermeasures, is urgently needed in order to secure the functions and performance of existing port, shore, and airport facilities above the required level as well as to promote their beneficial use.
  • This research theme includes study on the development and improvement of performance verification technology at the design stage, study on the enhancement of inspection and diagnosis techniques, which are essential for performance evaluation at the maintenance stage, and study on the prediction of the behavior and performance deterioration of structures and pavements, which is necessary for performance evaluation as well as selection and implementation of countermeasures, for the purpose of enhancing the technologies related to inspection, diagnosis,performance evaluation, prediction, and countermeasures.

Research Topics

 This research theme includes the following three topics:

  1. Investigation of Prediction Models of Materials Deterioration and Structural Performance Degradation
     This subtheme involves studying methods for evaluating the deformation resistance in regard to the long-term durability of various construction materials in the marine environment, designing upgrades and maintenance for cathodic protection under the seabed, examining the deterioration characteristics of the protective coating of marine steel structures, and evaluating the resistance of airport asphalt pavements to plastic deformation.
  2. Integration of Structural Design and Performance Verification Methods of Structures in Ports and Airports
     We are looking into partial factor settings for verifying durability and accidental loads, improving the verification accuracy of steel corrosion in marine RC structures, establishing life-cycle performance-degradation models for port structures and their components, incorporating maintenance considerations into structure design methods, incorporating performance verification and reinforcement design methods for reinforcing existing structures, and conducting simulations of performance degradation patterns of airport pavement structures.
  3. Integration of Inspection and Diagnosis Techniques for Life Cycle Management of Coastal Structures
     We are investigating data acquisition technologies by means of inspection and monitoring of structures utilizing nondestructive testing (NDT) methods as well as investigating the application of a health monitoring system to concrete and steel materials and structures, an operation system for non-contact thickness measurement of steel structures, and various other new measuring systems.

Activities in FY 2014

  • The long-term durability was evaluated for concrete, steel, and other materials using exposure tests in real environments. The endurance tests were interrupted because of facility improvement work on the longterm exposure test station, but the construction was completed at the end of FY 2014, and endurance tests have been restarted in sequence since the beginning of FY 2015. The influence of the interruption period will be considered when evaluating the results of the endurance tests.
  • We continued to monitor cathodic protection characteristics mainly under the seabed using actual structures (steel pipe piles of runway D of Haneda Airport, Minami-Honmoku steel-sheetcell wharf in Yokohama Port, etc.). Based on the results, we
    studied the design method of cathodic protection in the seabed.
  • We examined methods for formulating maintenance plans based on estimated life-cycle costs and summarized the methods for designing wharf structures considering progress and labor-saving in maintenance and management.
  • As a study on predicting the future performance of existing port structures based on capacity evaluation, we investigated the relation between the variation of deterioration of existing RC members and the structural stability of the members and carried out on-site tests at a cavity under an apron as well as experiments in the pavement test site. Furthermore,as a study on life-cycle scenarios considering the physical life expectancy of structures, we estimated the life-cycle cost of the superstructure of open-type wharves assuming several maintenance limits.
  • We extracted problems with the current method for evaluating the stripping resistance of asphalt pavement by conducting accelerated deterioration tests such as wheel tracking tests under aircraft tire pressure while collecting information on measures for separation prevention both in Japan and abroad.
  • We answered inquiries about maintenance technologies,organized Q&A examples (handling examples) for each theme, and updated the database.
  • We studied techniques for monitoring steel corrosion of RC members using embedded sensors, particularly the required number and installation positions of sensors. We also started to improve the inspection and diagnosis system for port structures. Furthermore, we started to develop effect-confirming sensors for corrosion-resistant petrolatum coating and started to conduct exposure tests for verifying the accuracy of the sensors.
  • We studied how to utilize sensor information for helping the teleoperation of superstructure inspection equipment and created a new test bed for small superstructure photographing equipment that enables such utilization. We also prepared a basic program for utilizing the observation information obtained by 2D scanners and created a prototype of a general-purpose program that links captured images with positional information. We devised a measuring method that reduces the reflection from deposits in non-contact wall thickness measurement and confirmed that more stable measurement results can be obtained by the method compared to conventional methods. Furthermore,we measured the acoustic penetration and reflection characteristics of FRP and others as basic data for measuring the wall thickness of piles and sheet piles covered by FRP protective covers.

Figure 1.1.1.14 Extraction of problems with the current method for evaluating the stripping
resistance of asphalt pavement

 

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