Comparing results of time domain fatigue design of steel catenary risers using linear and nonlinear riser soil interaction models under random waves

Steel Catenary Risers (SCRs) are still among the most popular types of riser systems and are widely adopted across deep water oil and gas projects globally. Fatigue design of SCRs are associated with high nonlinearity and it remains a challenge for riser engineers and researchers. In the Touch Down Zone (TDZ), the soil structure interaction model plays a vital role in the fatigue design and it becomes more complex when dealing with irregular waves and a nonlinear soil structure interaction model.

In this paper the effect of nonlinear and linear soil structure interaction models under randomly generated waves for a wide range of seastates are analyzed in time domain. Fatigue damage results under randomly generated waves are calculated in time-domain analysis. Sensitivity of the results to various parameters like the soil type model, the severity of seastates and the duration of dynamic simulations are discussed in detail. Results of this study give a better insight into the fatigue design of SCRs in TDZ.