ABSTRACT
Seismic safety of submerged floating tunnel (SFT) is one of the important factors of influencing application of the new structure, so it has important significance to investigate the seismic behaviour of SFTs. In this paper, SFT cable-tube coupling system nonlinear seismic model is established by simplifying the structure of SFT, and the seismic wave propagation mode in cable is constructed. Then, taking the coupling effect between cable vertical vibration and tube lateral vibration into account, the differential equations of the cable and tube coupled motion are derived by using Hamilton principle. In order to evaluate the SFT structural response to seismic events, the time domain dynamic response analysis is carried out by using variable separation approach and modal superposition method. The seismic behaviour of SFT in four cases are analyzed. The result shows that SFT seismic safety needs adequate reserves to ensure the structural safety and the cable vibration can inhibit tube vibration to some extent. The water resistance or damping can effectively weaken the cable vibration, and make the vibration energy of the SFT to be dissipated quickly. The cable maximum displacement tends to decrease with the increase of initial tension and the reasonable tilt angle of anchor cable is about 60°.
