Direct Integration Mode Superposition: A Simple Method for Dynamic Analysis of Submerged Floating Tunnel (SFT)

This article describes the use of simple methods to analyze the dynamic behavior of large-dimensional structures, such as submerged floating tunnels (SFT). Using this method the calculation process becomes simple and inexpensive because the solution can be obtained analytically. Based on the superposition mode method, it is possible to directly integrate the Euler-Bernoulli beam theory model, which is called the Direct Integration-Mode Superposition Method (DI-MSM). Using Hamilton's principle, the equation of motion in the EulerBernoulli Beam model is modified into the Equation of forced damped vibration. The solution of the equation is obtained by direct integration to obtain the displacement and natural frequency. Evaluation of the effectiveness of this method was confirmed by solutions using FEM as validated with previous studies. This method is simpler to be applied in analyzing other structures, especially continuous structures with large dimensions, which if using the FEM method will require relatively large computational costs and longer time.