Synopsis
The development of gas fields in a highly seismic zone in the Caspian Sea required an innovative offshore platform. Arup were the detailed designers of a self-installing gravity based structure (GBS) to meet this demand – the first such platform to be commissioned in the region.
Arup became involved after an elastic analysis based prescriptive design approach predicted the platform to have inadequate capacity to withstand signifiant seismic events. The Arup team adopted a performance based approach, in combination with advanced non-linear analyses, to demonstrate the suitability of the design for use in this location.
Non-linear time history soil-structure interaction finite element analyses were used to demonstrate that the GBS platform satisfied the performance requirements of ISO 19901-2. In addition, the performance based approach provided the client with an improved understanding of the likely response of the structure to a real earthquake and a greater ability to manage the risks associated with the facility.