R. El Nabouch¹, Q.B. Bui², O. Ple¹ and P. Perrotin ¹
1)  Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, LOCIE, 73000 Chambery, France
2)  Sustainable Developments in Civil Engineering Research Group, Faculty of Civil Engineering, Ton
Duc Thang University, Ho Chi Minh City, Vietnam.
Corresponding author: buiquocbao@tdt.edu.vn

Keywords: Earth construction, Rammed earth, Seismic assessment, Limit states

Abstract. Rammed-earth (RE) is a construction material which is manufactured from the soil. The soil is compacted in layers (about 10-15 cm thick) inside a formwork, to build a monolithic wall. RE material is attracting renewed interest throughout the world because of a significant number of existing RE buildings and the sustainable characteristics of this material: low embodied energy, substantial thermal inertia and natural regulator of moisture. This is why numerous research studies have been carried out recently to study different aspects of this material. Among different aspects, the seismic assessment of RE buildings 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. Two RE walls were tested. The walls were firstly loaded by a vertical force to simulate the dead and live loads in a building; then the walls were pushed on the top by a horizontal load 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. By basing on the case of unreinforced masonry, the present paper proposed four limit states for RE walls: LS1 (no damage), LS2 (slight damage), LS3 (moderate damage) and LS4 (extensive damage). From the damage evolution observed during the tests, the following values of inter-story drifts δ were proposed for RE walls: LS1: δ < 0.1%; LS2: 0.1% ≤ δ < 0.3%; LS3: 0.3% ≤ δ < 0.6%; LS4: δ ≥ 0.6%.