Strongly directional currents in the calculation of structural reliability and response-based design conditions

In some locations, current contributes measurably to the hydrodynamic force on structures, while its amplitude may have a greater dependence on direction than does wave height. We have extended our random storms method of calculating response-based basign conditions and statistics of extreme structural response in order to resolve the influence of such strongly directional currents on directional load statistics. We have applied the extended method to a southern North Sea location where, at least by North Sea standards, currents are relatively large, though they do not dominate the drag loading on a lattice structure. We have calculated response-based design conditions and investigated the significance of the improved resolution for estimates of structural failure rate under extreme storm loading. The improved resolution of the current direction has no consequence either for this location or for other North Sea locations.