Abstract
Numerous fatigue cracks have been found in steel bridges. To maintain steel bridges, repair and retrofit methods of such fatigue cracks have been developed. One technique we developed was to produce plastic deformation of the steel surface near the crack in order to close crack opening by using air tool. This method is called Impact Crack Closure Retrofit treatment (ICR treatment). We carried out plate bending fatigue tests of out-of-plane gusset specimens. Fatigue cracks at turn-around welds and those which propagated 10mm were ICR-treated. Fatigue test results of specimens after ICR treatment showed significant improvement of the remaining fatigue life.
