Bridge Screening based on VRA車両振動分析による橋梁損傷検知
We are now facing the problem of aging bridges. This problem increases the cost for bridge maintenance, though there is often some limiting conditions for public budget. Even if we could solve the financial problem, the number of veteran engineers who can inspect bridges is not enough, because that of bridges is much larger. In Japan, there exist more than 700,000 normal bridges, while a half of them will be "Aged" in 2020. Maybe, you could expect that the market for bridge maintenance would be huge in the future, and that it would be attractive. Despite the great demand there, our supply capacity cannot keep up. To implement our supply side problem, it is necessary to develop a technology to conduct bridge inspection quickly and at low cost. The mission of Yamamoto Lab. is to contribute through practical application of that technology.
In order to achieve this mission, Yamamoto Lab. has proposed VRA (Vehicle Response Analysis) method for bridge damage detection. This is a kind of vibration-based SHM (Structure Health Monitoring), but sensors are installed only on passing vehicles, not on the bridges. It is thought that the estimation accuracy of bridge state is low, but because of its high efficiency it can be expected to apply this technology to bridge screening.
This is a conceptual diagram for the bridge maintenance system based on screening. Just by running a monitoring vehicle, we can evaluate the states of bridges. Once that is possible, we will be able to dispatch engineers to the "Suspicious Bridges" preferentially.
The basis concept of VRA method is inspired by Yang's "Indirect Approach" proposed in 2004. They installed a sensor on the travelling vehicle in order to estimate the bridge frequency. On the other hand, VRA method focuses on the bridge mode shapes, because they are expected to be more sensitive to local damage. To estimate mode shape, several sensors are installed on the vehicle, in this study.
Reference:
- Yang, Y.B., Lin, C.W., and Yau, J.D.: Extracting bridge frequency from the dynamic response of a passing vehicle, Journal of Sound and Vibration, Vol.272, pp.471-493, 2004. PDF
Explanation in Japanese: 詳細説明
SHM using MEMS sensorsMEMSセンサを用いた橋梁振動モニタリング
To reduce the cost on SHM (Structure Health Monitoring) for bridge structures, the applicability of MEMS (Micro- Electro- Mechanical System) sensors are examined. We will open the recipe for assembling the sensor with MEMS parts.
Improvement of Solar Chimneyソーラーチムニー発電の高効率化
We are trying the improvement of calculation efficinecy of thermal fluid dynamics through developing a new algorithm. One target of this challenge is Solar Chimney.
Solar Chimeny, or Solar Updraft-tower Power Generator, is a electric power generator of a renewable energy.