Patch plate repair method with spot welding for corroded members in steel structures has been investigated. The proposed welding condition can apply to the assemblage of thin and thick steel plates, and its tensile shear load of one spot welding was 11kN. When the patch plate repair method with spot welding was applied to assemblage base plate of 9mm and patch plate of 1.6mm, at least 2 columns were necessary to prevent the rupture at welded joints. Based on analysis results, first and second column spot welds from the patch plate edge transfer about 80% and 20% of total carrying load in the patch plate. Fatigue test results of spot welded joints showed JSSC D class.
