Development of a New System for Detecting Fatigue Cracks in Steel Bridges.

摘要

The nondestructive detection and characterization of fatigue cracks during field inspection of steel bridge structures are put in perspective in terms of the magnitude of the problem and viable nondestructive methods. The results of nondestructive method assessment,selection,evaluation,and experimental confirmation are presented in detail. Developed as a useful and effective solution to the problem,the inspection system consists of two independent,complementary,lightweight,battery-powered electronic instruments-an acoustic crack detector (ACD),which uses ultrasonic principles,automatic signal analysis,and a simple digital data display for rapid survey,and a magnetic crack definer (MCD),which uses magnetic principles and a simple ON-OFF light data display for defining the precise location and crack length. The features and functioning of the equipment are briefly described,and laboratory and field demonstrations,presentations,and field inspections are reviewed. The technical basis for equipment development,including equipment concepts,is summarized.