Numerical study on the compression-bending response of grouted connections in offshore structures

Abstract

Grouted connections (GCs) are widely used to link the substructures and towers for offshore wind turbines and transfer various loads from the turbine and tower to the substructure. Extremely complex stresses are developed in these composite connections formed with steel pipes and grout fillings. This paper presents a numerical study, using ABAQUS, on the mechanical response of GCs under axial compression coupled with bending. The effect of axial load ratio on the moment-rotation responses, contact stress between steel pipes and grout, as well as compositions of flexural capacity. Further study is conducted on the stress distribution in the grouted connection under axial compression coupled with bending, and the stress distribution was derived with python script. Analysis shows that, axial load ratio plays a non-negligible role and the distribution of contact stress differs from that recommended by current design guide. These should be considered with caution in industrial design. In addition, this paper also proposes a method to derive the contact stress from numerical model constructed with Abaqus. The results show that contact pressure and shear keys provide the main components for the flexural capacity and the sum of Mp and Mshear-keys accounts for about 75% of the total capacity. And the values of the non-uniform coefficient of shear keys ηsk are all larger than 0.75 which shows that the force distribution between shear keys is extremely uneven. The outputs of this paper provide a further understanding of the GCs subject axial compression coupled with bending.