The analysis of structures subjected to moving loads and using the results of such analysis in design of bridges is an active research area in dynamics of structures. Nowadays, the results of the mentioned analysis become more important due to the presence of high speed trains and vehicles. Moreover, health monitoring of structures by using wave propagation analysis is vital in some fields like aerospace industries. Regarding these points, in this thesis, spectral element method in frequency and time domain is employed to respond to the demanding of more precise analysis in this area. Although spectral element method in frequency domain (SEM) has been developed during last two decades, however, this method has not been used to analyze structures subjected to moving loads. Thus in this thesis SEM is used for analyzing Euler beams and in-plane vibration of curved beams subjected to moving and impact loads. For this purpose curved beam dynamic stiffness matrix and the subsequent procedures of applying it in SEM are developed. In the fourth part of the thesis spectral element method in time domain (SEMT) is used to analyze ordinary elastic and FGM plates. The related dispersion relation of each plate is evaluated and used to verify numerical results. Finally ordinary elastic plate subjected to an arbitrary moving load is analyzed using higher order Legendre spectral elements. Numerical results from SEM or SEMT show very good agreement with analytical ones, which indicates the strength of the methods in dynamic analysis of structures. Key words: dynamic analysis, spectral element method in frequency domain, spectral element method in time domain, wave propagation, impact load, moving load.
