| Abstract Scope |
Welded in-plane gusset joints have been used in many structures. The fatigue failure design and evaluation procedures for welded in-plane gusset joints are available through codes and standards. However, the fatigue evaluation of the welded in-plane gussets has been relatively less studied. Furthermore, the failure criteria of the welded in-plane gusset joints are not clearly defined because the crack generally starts from the weld toe of one edge and grows into the plate.
In this study, three different fatigue assessment methods for welded in-plane gusset joints were compared to investigate their accuracy and applicability using existing codes and standards procedures. The first one is the nominal stress method, which is categorized as the global method, and stress calculation using FEA is not needed. The second method is the hot spot stress method, which requires stress calculation using FEA. The third method is the ASME and API procedure for the master S-N curve using the equilibrium-based structural stress method. This requires structural stress calculation using FEA. To apply the structural stress concept, the failure criteria were defined based on joint symmetric and unsymmetric conditions. For this study, well-documented fatigue test data for welded in-plane gusset joints was collected and applied.
Partial failure cases that show a finite crack length in the plate were also investigated. In some applications, very stringent failure criteria may be used, showing a finite crack size rather than complete failure. For these cases, the modified equilibrium-based structural stress procedure was proposed. Applying the partially failed fatigue data, the applicability of the proposed procedure using the equilibrium-based structural stress method was investigated. Once the modified procedure for partial failure cases was applied, it was observed that all fatigue data, regardless of complete failure or partial failure, were mingled together within the master S-N curve. |