Reliability analysis of a pile design

This paper presents a stochastic pile design for a wellhead platform designed for Danish waters. The relevant failure modes for both ultimate and serviceability limit states are defined. Failure modes for the pile as well as failure in the soil are thereby considered. Reliability criteria are suggested based on requirements formulated by the Nordic Committee for Building Structures. An uncertainty modeling for the environmental conditions, the response and the soil stiffness and strength is suggested. The choice of distribution types by and large follows that suggested by the Nordic Committee for Building Structures. The effects of spatial variation of soil properties are assessed both in terms of varying positions of layer boundaries and in terms of spatially varying soil properties. The model uncertainty in the soil strength for axial compressive and tensile loading is quantified. The most important uncertainties are due to uncertainties in the extreme environmental parameters and load model parameters, and for the soil failure modes also due to the model uncertainty. The uncertainties in soil stiffness, strength and spatial variation play a very small role in all failure modes.