| Summary: | 碩士 === 國立中央大學 === 土木工程研究所 === 99 === In the past extreme earthquake, observed from the damaged bridges, bearing failure, column failure and deck unseating caused a more serious loss. Therefore, it is full of curiosity that how large earthquake will cause a bridge to collapse and how the ultimate state will be. The Vector Form Intrinsic Finite Element (VFIFE), a new computational method developed by Ting et al. (2004), is adopted in this study. The formulation of VFIFE type 3D frame element includes a new description of the kinematics that can handle large rotation and large deformation, and includes a set of deformation coordinates for each time increment used to describe the shape functions and internal nodal forces.
Some kinds of new 3D VFIFE elements and analysis methods are herein developed for analyzing the target bridges. Through numerical simulation of examples and comparison with the Finite Element analysis (SAP2000), the developed elements and analysis methods are verified to be feasible and accurate. In the past, VFIFE was used Central Different Method to be analysis method, there are numerical disperses when to solve the Rayleigh damping analysis. Implicit time integration method (Newmark-β) is adopted in 3D VFIFE. Incremental formulation of the equation of motion is used to do iteration and to solve the response at next time step (i+1) including the displacement, velocity and acceleration. Furthermore, this calculation is also used to calculate the internal resultant force and the internal damping force exerted by the elements surrounding the particle. Finally, this study analyzes the ultimate situation of bridges through 3D numerical analysis and input two directions of horizontal ground motions to investigate the extreme functions of the bearings, columns and unseating prevention devices. Then predict the collapse situation of target bridges.
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