Fatigue Design Of Driven Piles For Deepwater Applications

Some codes of practice call for the consideration of the fatigue damage caused to piles during both installation and in-place operations. However, no codified methodology or criteria for fatigue design exist. Recent efforts to revise the foundation design for tendons in API RP2T made abundantly clear the need to establish both procedures and criteria. This paper addresses the load and criteria aspects involved in the fatigue damage evaluation of welded piles due to installation and operation, including piles with protruding attachments, such as padeyes for mooring lines or receptacles for tendon bottom terminations. A methodology to evaluate local stress histories due to driving is discussed, including pile response to driving, local and residual stresses, and cycle counting. A review of practices with respect to safety factors is presented and safety factors consistent with fracture-critical components are suggested.