Rammed earth under horizontal loadings: Proposition of limit states

Abstract

Rammed earth (RE) is a construction material manufactured from the soil. This material attracts the attention of numerous scientific investigations during the past decade due to its sustainable properties. The performance of RE buildings under horizontal loadings remains an important topic to be investigated. This paper presents an experimental study which identifies the limit states for the in-plane seismic assessment of RE walls. Four RE walls were tested under bi-axial loading: first a vertical force was applied on the top of the wall to simulate the dead and live loads in a building; then a horizontal force pushed at the top the walls to simulate a seismic action. The cracking evolution was recorded by using the DIC (digital image correlation) technique in which the displacement fields were determined by comparing the images taken after and before the loading. Based on the damage evolution observed during the tests and on a similar approach of unreinforced masonries, the present paper proposed four limit states for RE walls corresponding to the inter-storey drift δ: no damage (before LS1) and slight damages (before LS2): δ < 0.1%; moderate damages (before LS3): 0.1% ≤ δ < 0.3%; extensive damage (before LS4): 0.3% ≤ δ < 0.6%; compete damage or collapse (after LS4): δ ≥ 0.6%. This is the first time these limit states are proposed for RE walls.