2022 Volume 71 Issue 3 Pages 303-309
It is said that about 50% of all bridges in service will be in service for more than 50 years by 2030. Therefore, measures against aging bridges are an issue. Bearing which is one of the bridge members has a role to support the dead load and live load of the superstructure. Furthermore, it has a function to cope with expansion and contraction of the girder due to temperature changes. However, the quantitative evaluation of the deterioration of the bearing and the effect on other members are unknown. In this study, we targeted bridges erected in Yamagata Prefecture. We measured the behavior of the target bridge due to temperature changes and conducted a static loading test using a 14tf truck. The deck of target bridge was replaced in 2019, and experiments were conducted before and after that. When the behavior with temperature change was compared before and after the replacement, it was confirmed that the deck replacement had a certain effect. The authors conducted a reproduction analysis of behavior due to temperature changes. As a result, it was confirmed that the measured value was between the analysis value considering deterioration and the analysis value not considering deterioration. The authors introduced a spring element during the analysis to quantify the degree of deterioration of the bearings. The authors performed an analysis on a model with a spring element and compared it with the experimental results of a static loading test. As a result, it was confirmed that the analysis value and the measured value of the natural frequency and the vertical displacement are approximated by changing the spring constant. From this, it is considered that this method is effective for quantifying bearing deterioration.
