This paper presents the results of tests conducted to investigate the influence of fracture toughness, weld defect and strain rate on fracture behavior. Tensile tests of welded butt joint and cyclic tests of welded beam-to-column connection with artificial defects were carried out, with combination of steel and welding wire, temperature, type and size of defect and loading speed as test variables. The experimental results show that maximum strength and plastic deformation capacity of the welded connections are attributed to the fracture toughness rather than to the size of defect and the strain rate.
