Out-of-plane behavior of rammed earth walls under seismic loading: Finite element simulation

Rammed earth (RE) is a sustainable material which is made by compacting the soil in a formwork. The earth-quake performance of RE structures is an important topic, however the out-of-plane seismic behavior of RE structures has not been thoroughly investigated in the literature. The objective of the present paper is to study the out-of-plane seismic behavior of RE walls by using finite element method. The model used involved the concrete damage plasticity (CDP) model to simulate the nonlinear behavior of the earthen layers, a surface-based cohesive behavior to simulate the linear and nonlinear behavior of the interlayers (between the layers). The parameters of the model were first validated through the simulations of available experimental tests in the literature for both in-plane and out-of-plane loading. Then, a U-shaped RE wall was modelled which was composed of one longitudinal wall (4.6-m-length x 2.4-m-height x 0.5-m-thickness) and two transversal flanges (2-m-length). Effects of the bond beam (on the top of the walls), the interlayers and different earthquake amplitudes were studied. The results showed that the implementation of the interlayers in the model had clear influences on the ultimate load and the failure modes but the inter-storey-drift was few affected; the bond beam played an important role for the out-of-plane seismic behavior of the RE wall. The performance of the studied RE structure was satisfying until a seismic amplitude of 0.223 g.