Prediction of Fracture of Welded Moment Connection under Varying Amplitude Cyclic Loading

This paper presents a method to evaluate plastic deformation capacity of welded beam-to-column connection used for moment frames until ductile fracture due to cyclic loading with varying deformation amplitudes. Constant deformation amplitude loading tests were conducted to investigate the relationships between deformation capacity until fracture and deformation amplitude. From test results, the crack propagation is formulated as the function of number of cycles and the deformation amplitude to evaluate the damage to the welded connection of a beam flange. In order to verify validity of the proposed crack propagation formulation, varying deformation amplitude loading tests were conducted. From test results, it is found that the deformation capacityaffected not only the amplitudes but also the orders, which indicates that the Miner rule is not suitable for the prediction of fracture with varying deformation amplitude. The proposed formulation well evaluates damage and simulates crack propagation until fracture.