The setting of Acoustic Emission detecting parameters in running of steel structured
Acoustic Emission technology is still at the starting stage of monitoring in domestic bridge. To resolve the problem that Acoustic Emission detection parameters in scene are determined. Based on lead-breaking tests confirm threshold and time parameter. Studying on the characteristic of signal propagated and the attenuation laws of velocity and amplitude, it gets references for Acoustic emission technique in detection of the bridge.
Monitoring Damage of Arch Bridge Suspender Using Acoustic Emission Technique
Conventional non-destructive methods can't be dynamically monitored the suspenders'damage levels and types,so acoustic emission(AE) technique is proposed to monitor its activity.The validity signals are determined by the relationship with AE rise time and duration time.The ambient noise is eliminated using float threshold value and placing a guard sensor.The cement mortar and steel strand damage level is analyzed by AE parameter method and damage types are judged by waveform analyzing technique.Based on these methods,all the suspenders of Sichuan Ebian Dadu river arch bridge have been monitored using AE techniques.The monitoring results show that AE signal amplitude,energy and counts can visually display the suspenders'damage levels,the difference of waveform and frequency range express different damage type.The testing results are well coincide with the practical situation.
CRACKS IN A CONCRETE BRIDGE
This paper describes acoustic emission monitoring of cracks in the anchor block of a prestressed concrete bridge. As the bridge was closed to traffic upon the appearance of the cracks, an ideal opportunity was presented to study the value of the technique in a real life situation as distinct from laboratory tests. The structure was monitored before and after remedial work was undertaken with the object of determining whether any emissions generated could be related to the condition of the anchor block. Temperatures and crack widths were also recorded to assist with interpretation of the acoustic emission data. The bridge was a two-span continuous structure of post-tensioned segmental construction with plastic coated unbonded prestressing tendons housed inside a single cell box. The variations found in acoustic emissions with time and temperature are shown graphically and some conclusions are drawn. There was no regular pattern to the emissions that could be related to temeprature although there were several indications that some of them were thermally induced. (TRRL)