The purpose of this study is to develop a new evaluation method for ductile crack initiation and propagation in steel piers with thick-walled sections. To this end, elasto-plastic cyclic analyses of unstiffened box-sectional steel piers are performed using a three-step two-parameter ductile fracture model that simulates crack initiation and propagation. In this study, the ductile fracture parameter is changed from the damage propagation energy to the displacement at element failure, and the N-VG model proposed by authors is employed. As a result, the newly proposed failure analysis procedure is possible to evaluate the ductile fracture more precisely than the conventional method.
