Ultrasonic testing of stresses with longitudinal wave – experimental application to evaluate truss bridge

Abstract

Paper presents ultrasonic testing of stress changes in elements of steel structure. Basis of ultrasonic method are explained, formulas to calculate stress values based on changes of measured time of flight of ultrasonic pulses are given. Stress evaluation was based on both elastoacoustic effect and deformation of element under test. Ultrasonic probeheads used in measurements and measuring device are described. Results of stress monitoring in two elements of steel railroad bridge are presented – in I-section girders and diagonal truss member. Stress changes registered during passages of rail vehicles of various mass, traveling across the bridge with various velocities, in both directions are presented. Readings taken with two channel equipment during passage of cargo train showed asymmetry of stresses in both girders.