Investigation of ۱D site response using linear and equivalent linear analysis method

This study investigates the response of ۱D free-field column using linear and equivalent linear analysis method. To do time history analysis, finite element time domain program has been prepared called “IDAMP” which able to use perfectly matched layer as an absorbing boundary in the boundaries to simulate semi-infinite environment. This program primarily is developed in international institute of earthquake engineering and seismology (IIEES) to solve dam-foundation interaction considering linear behavior of materials and later it was improved and the ability to perform equivalent linear analysis was also added to it. IDAMP uses four nodded quad elements and able to simulate multi-layer column with different materials and different shear modulus reduction and damping ratio against shear strain relations for equivalent linear analysis. An acceleration time history based on Tohoku earthquake in Japan ۲۰۱۱ recorded in FKSH۱۱ station has been chosen and applied to prepared models; one with fixed base condition and another with PML in the base. Results showed that equivalent linear analysis can estimate site response with proper accuracy. Also, using PML in the base reflection from boundary will be eliminated. Also, results showed that adopted procedure for using PML in equivalent linear analysis was appropriate.

Keywords:

wave propagation , free-field , perfectly matched layer , equivalent linear analysis , IDAMP