Deterioration diagnosis of wooden bridges by nondestructive testing method ( I ) an investigation of the ultrasonic propagation method

Ultrasonic propagation velocity across wood fiber direction was measured in wooden bridges in order to investigate the possibility of nondestructive deterioration diagnosis of wooden bridges. The measurements were carried out for three different types of wooden bridges. The periodical measurement was also made for one of them to investigate its secular change. The results were : (1) The histograms of ultrasonic propagation velocity could show the total deterioration states of the wooden bridges. The histograms reflect the deterioration of three different types of wooden bridges. (2) Cumulative probability curves of ultrasonic propagation velocity were effective to monitor time-dependent change of the deterioration of wooden bridge.