Seismic Response of MSE Walls with Various Reinforcement Configurations: Effect of Input Ground Motion Frequency

Abstract

Mechanically stabilized earth (MSE) walls perform well under earthquake loads, and hence they are preferred in earthquake-prone regions. The multifaceted load transfer between the components of the MSE wall under seismic loads can be captured using numerical analysis. This study presents the results of a series of numerical analyses performed to investigate the effects of the frequency of the input ground motion on the seismic response of MSE walls. MSE wall design configurations were prepared using various reinforcement designs (length, vertical spacing, and stiffness). A frequent wall height of 8 m was selected for the analysis. Using two-dimensional finite element analysis, each MSE model was excited with seven (7) different input ground motion accelerograms with equal Arias Intensity, but with different frequencies ranging between 1 Hz and 8 Hz. The results of the numerical analyses indicated rotation at the top of the MSE wall in seismic conditions. The frequency versus acceleration plot for a point close to the top of the MSE wall indicated peaks for the excitations with frequencies f = 1.5 Hz and f = 4 Hz, which are close to the estimated natural frequency of the overall model (including the foundation soil) and the MSE wall, respectively. The highest normalized acceleration amplification factor solely within the MSE wall was recorded as 1.86 for the excitation with a frequency equivalent to its fundamental frequency (f ≅ 4 Hz). In this study, the 8 m high MSE wall models placed on a firm clayey foundation soil with the reinforcement parameters with length over height ratio in 0.5–1 range, axial stiffness in 600–1200 kPa range, and reinforcement vertical spacing in 0.4–0.6 m range performed satisfactorily under moderate seismic loads.