Analysis and Design of an Ice Wall Framing System for an Arctic Drilling Structure

Abstract

The exterior shell of a concrete base structure for an arctic oil drilling platform must be designed to resist extremely high local ice pressures. Stringent draft criteria for deployment of these structures in shallow waters require that the exteri or shells, commonly called ice walls, have minimal weight in conjunction with maximum strength.These conflicting requirements are satisfactorily balanced by the selection of an arch shape on the interior face of the wall. This geometry induces arching action within the ice wall plate to resist ice loads in compression, thereby minimizing principal tension within the concrete. The development of principal tension in a concrete structure limits its ability to resist external forces. This paper describes the design of a prestressed concrete ice wall which satisfies these load, weight, and material constraints.

Punching shear resistance of lightweight concrete offshore structures for the Arctic :

“…Also, monitoring of actual [25] ; -1600 psi on 10 ft^or less and 1000 psi on 210 ft^, ACES, 1984 [26]; and -900 psi on 5 ft X 5 ft area. Super CIDS, 1984 [27].…”

“…The exterior walls of the verticalsided gravity structures may be configured as an arch shape to induce arching action, thereby reducing principal tension stresses in the wall [25].…”

“…Schlechten et al [25] Figure 5b. Design of the outer wall is controlled by flexure and out-of-plane shear forces.…”