IMPACTⅣ is a measurement system to evaluate condition of bridge substructure by using natural frequency as an index. The value of natural frequency is calculated from the recorded response acceleration/velocity after hitting the top of the structure using the iron ball as illustrated in Figure 1. A vibration exciter is also used to apply the mechanically manipulated excitation to the structure, which make it possible to apply the system to retaining structure.
- Easy to conduct
- High repeatability
- Quantitative evaluation
- Possible to detect deformation of invisible location
Condition rating of bridge substructure and retaining structure
- A mobile PC (with installation of IMPACT Ⅳ software）
- Sensors (Wireless/Cabled/accelerometers are applicable)
- Vibration exciter
- Amplifier and wave generator
- Railway Technical Research Institute: Maintenance Standards for Railway structures (in Japanese), 2007.
- Nishimura, A., Okumura, F. and Tanamura, S.: Integrity Judg-ment of Railway Bridges by Percussion Tests for Structure Response, Quarterly Report of RTRI, Vol. 29, No.4, pp.184-189., 1988.
- Nakajima, S., Shinoda, M., Abe, K., Mai, T. and Ehara, T.: Study on inspection method for railway existing retaining walls using vibration testing, IS-Hokkaido 2012: 2nd international conference on transportation geotechnics, 2012.
- Shinoda, M., Nakajima, S., Abe, K., Tetsuo M. and Ehara, T.: Development of nondestructive inspection method of railway bridge substuructures with small vibration exciter, Proc of the International workshop on ICT in Geo-Engineering (ICTGE2012), 17-18 May 2012.