Measurement of Service Loading and Development of Monitoring System for Durability Evaluation of Highway Bridges due to Social and Economic Changes.

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(1) Measurement of Traffic Loading in Service and its Engineering ApplicationA Bridge Weigh-in-Motion system using signal corresponding to reaction force was developed, and it was applied to several bridge locations in major highway and expressways near Nagoya. Fatigue damage index based on Miner's cumulative damage rules was developed, and relative damages for different members of bridges caused by different truck types were evaluated. A new technique was also developed, where bridge vibration was simultaneously measured with axle load and vehicle weight to correlate them with traffic induced vibration.(2) Monitoring of Highway Bridges and Overhead Sign StructuresMonitoring of overhead sign structures and lighting poles was carried out from vibration viewpoint and stress cycles viewpoint in order to correlate vibration with fatigue durability. Visual monitoring and simple deflection meters were also applied to actual lighting poles in order to evaluate their vibration characteristics. Fatigue tests of base detail of such overhead sign structures were also carried out.(3) Development of Models for Evaluation of Fatigue Durability of Welded MembersFatigue tests were carried out for welded joint of unpainted weathering steel exposed to ambient air environment for about 25 years. So-called one-millimeter method, which used FEM analytical result, was developed to evaluate fatigue strength of complex welded detail. Low cycle fatigue tests was also carried out to develop evaluation model of steel in low cycle fatigue region, where image analysis was used to obtain large strain with relative accuracy.