In this thesis, the author investigates experimentally and numerically the fracture behavior of an electron beam welded joint made from two butt S355 plates. The 2D Rousselier model, the Gurson-Tvergaard-Needleman (GTN) model and the cohesive zone model (CZM) were adopted to predict the crack propagation of thick compact tension (CT) specimens. Advantages and disadvantages of the three mentioned models are discussed. The cohesive zone model is suggested as it is easy to use for scientists & engineers because the CZM has less model parameters and can be used to simulate arbitrary crack...