Abstract
A submerged floating tunnel (SFT) is propounded as an efficacious alternative to conventional bridges and underground/submerged tunnels for crossing deep waterways. SFT designers must ensure safe margins and develop approaches to prevail a wide range of plausible situations related to transport, wave, natural vibrations etc. to evaluate the structural stability. To date, only limited researches on this field have been performed to illustrate the significance of seaquake analyses and their effects have been underlined. The present paper intends at numerically simulating a two-dimensional (2D) fluid-structure interaction (FSI) problem in order to scrutinize the dynamic response of an SFT system under bidirectional earthquake actions. Hydrodynamic Pressure due to seismic base excitation is considered as independent nodal variables to represent the gravity influenced inviscid, compressible and irrotational fluid flow effects and the tunnel shell is considered as flexible. This work exposes the importance of the input seismic excitation characteristics that governs the distribution of the induced internal acceleration/force around the lining of the tunnel. Numerical results indicate that the increment rate of the internal acceleration in high SFT caused by vertical ground motion is nearly by 200% when compared to the low-laying tunnel. It is confirmed that long-period record may amplify the overall response of the SFT (up to 80%) when the tunnel approaches the ocean surface, as well as the mooring tensile force to a lesser extent. Finally the proposed coupled numerical procedure suggests that earthquake response spectrum in various intensity levels has an influential role in the response of long-span SFTs and special attention should be paid to the seismic design of such structures.
Published Version
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