This paper presents a numerical model that is used to estimate the structural response of a submarine pipeline with concrete weight coating subjected to loadings commonly encountered in pipeline installation and operation phases. Findings from parametric studies performed with the numerical model are used to widen the applicable range of the simplified concrete crushing criterion in DNV-OS-F101 (2013) and formulate a rational approach for the design of pipeline concrete weight coating under typical installation and operation conditions. The rational design approach will allow for potential selection from a wider range of installation vessels and relaxation of the installation weather window criterion. The design method also provides insights into the strain concentration in the field joint at different strain levels, which is used to assess the field joint welding integrity for pipeline in free spans and in high strain conditions.
The numerical model considers nonlinearities in steel and concrete material stress and strain, as well as complex adhesive behaviour of the anti-corrosion coating. Good agreement is obtained between the numerical results and existing experimental data for all the sections along the pipeline model where comparisons are made on moment–strain global behaviour, sliding from the concrete coating, hot spot strain near the field joint and concrete strain.
The numerical program is performed within the scope of Phase 1 of the joint industry project called “Design of concrete coating for submarine pipelines”. Laboratory tests to check and improve the numerical model are planned for Phase 2.