Design recommendations for grouted pile sleeve connections

Abstract

Failure of the grouted connection on a large number of offshore wind generator towers of monopile design initiated a critical review of the design recommendation of pile-sleeve connections for offshore structures. The failed connections were made without shear keys while connections with shear keys are most common for oil and gas platforms of the jacket type. As the design basis for grouted connections for wind mills was based on offshore practise a review on the background for the design codes ISO 19902 [3] and API RP-2A [5] revealed that adequate recommendations was not given in all cases. The increased focus on these connections led to the start of several research projects including laboratory testing. This paper presents proposals for improved design recommendations in light of the lessons learned from the observed failures and recent research.The proposals are formulated as practical design recommendations that can be implemented into offshore structural design codes.