Main issues of the structural analysis of SFT against environmental loads

The Submerged Floating Tunnel (SFT) is an innovative concept for crossing waterways. It is a tube, submerged at a specific depth, fixed in position through anchorage systems, providing opportune restraints and stiffness against service and environmental loads. Numerous feasibility studies and preliminary designs have been carried out up to today, but no SFT has been realized yet. However the SFT solution attracts more and more attention, having several advantages with respect to traditional structures. The focus of this paper is on the fundamental aspects related to the structural analysis of the behavior of SFT against environmental loads, such as hydrodynamic and seismic actions, based on a literature review. In particular, theoretical evaluations and numerical analyses on SFTs solutions adopting different cross-sections, structural materials, support systems, joints, under diverse imposed loads, are presented and discussed.