PARAMETRIC STUDY OF STRESS CONCENTRATION FACTORS IN THREE-PLANAR TUBULAR KT-JOINTS SUBJECTED TO OUT-OF-PLANE BENDING LOADS

The substructure of a jacket-type offshore platform is a space frame composed of circular hollow section (CHS) members. The intersection of CHS members in which the prepared end of brace members are welded onto the undisturbed surface of the chord member is called a tubular joint. Tubular joints are subjected to wave induced cyclic loads and hence they are susceptible to fatigue damage due to the formation and propagation of cracks. Significant stress concentrations at the vicinity of the welds are highly detrimental to the fatigue life of a tubular connection. For the design purposes, a parameter called the stress concentration factor (SCF) is used to quantify the stress concentration. This calls for greater emphasis in accurate calculation of the SCFs to estimate the fatigue life of offshore structures.