Abstract: The structure comprises a concrete monolithic caisson (3) consisting of a top slab (5) and a bottom slab (5') resting on a seabed. Two concentric peripheral walls (6, 7), an inner and an outer respectively, are designed to withstand the impacts of icebergs. These two walls (6, 7) extend substantially vertically between the slabs (5, 5') and are rigidly connected with them. Vertical partitions are arranged between the two walls so as to connect them in a lattice structure. Vertical defensive elements (8, 9) are disposed over at least a part of the outer periphery of the caisson. The defensive elements (8, 9) are integral with the outer wall of the caisson (3). These caissons are intended for a platform structure located in Arctic regions for production in a hydrocarbon field.