The principal aim of this paper is to study the fracture behavior in tubular connection of offshore platforms (Brace Caisson) subjected to wave loading. Fracture mechanics aspect on the assessment of crack tip severity under cyclic loading condition is explored. A series of 3D analyses are carried out using the ABAQUS finite element software to study the effects on the dynamic response of the change in support conditions at the seabed. The effects of wave height, wave period and wave velocity on platform behavior are studied. The results from time history analysis are characterized using Wavelet Analysis in order to obtain the response pattern due to wave loading. These analyses allow the frequency response of the jacket structures to be described in the time domain. These results give a clear view on the response of jacket structure. The important parameters on offshore modeling have also been identified and discussed in this study. In order to assess the crack tip severity of the crack at the tubular connection, the 3D-submodel of through-wall crack pipe is modeled within the full 3D beam element of the brace caisson. The fracture characterizing parameter (CTOD) is then extracted from the crack tip region. Finally, the CTOD results can be used to assess the crack tip severity of the connection.
In general, offshore structures can be designed for installation either in protected waters or in the open sea such as lakes, rivers, bays and many kilometers from shorelines. These structures may be made of steel, reinforced concrete or a combination of both. However, due to the inherent ductility available in appropriately manufactured steel, steel structures become one of the most popular types of structures for resisting dynamic loading conditions such as earthquake and wave loading.