Pile Driving Dynamic Loads On Offshore Structures

Reducing conservatism in jacket designs based solely on environmental loads can make other loading mechanisms which were not of concern in the past a dominant design parameter. One of these mechanisms is associated with the dynamic loads induced during pile driving. Acceleration and strain measurements during installation of two jackets in the North Sea illustrate that both tubular joints and sacrificial anode attachments can be subjected to a high level of fatigue damage during pile driving operations. The measured vibration response during pile driving can be simulated by performing time-domain dynamic analysis of the jackets. A load pulse with a duration of 0.2 sec is applied at the first pile guide inside the jacket leg. The U.K. Department of Energy T curve appears to be more appropriate for use to predict fatigue damage during pile driving than the API X curve.