Fatigue Research on Welded Joint of Steel Beam-column Connection

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The low-cycle fatigue strength of welded joints steel beam-column connection which were subjected repeated stresses wind loads were investigated experimentally.The tested cruciform specimens were modeled boam-to column connection with K-groove of full penetrated and/or partial penetrated welding. And weding methods were CO_2 gas are shielded and submerged are welding.The treatments in welding joint were as welded and/or finished by sander grinder.The results of low-cycle fatigue tests were as follows,1.The weld toe ground increased the crack initiation life, but there were few influences of difference between as weld and finish treatment on the fatigue strength.2.The crack initiation life of as welded joint was about 10% to 20% of one of base metal, and the crack initiation life of toe ground joint was about 20% to 30%. But the fatigue strength of both conditions was about 20% to 30% of one of base metal.3.There were few influence on crack initiation life and fatigue strength difference of welding methods-CO_2 gas are welding and submerged are welding.4.Fractography showed that fracture models were fatigue fracture one with formed striation when strain ranges was under about 1.5% and was ductile fracture one with dimples when strain range was over about 1.5%.