11Nowadays, rammed earth construction is attracting renewed interest throughout the world thanks to its 12 "green" characteristics in the context of sustainable development. Firstly, using a local material (soil on site 13 or near the site), rammed earth constructions have very low embodied energy. Secondly, rammed earth 14 houses have an attractive appearance and present advantageous living comfort due to substantial thermal 15 inertia and the "natural regulator of moisture" of rammed earth walls. This is why several research studies 16 have been carried out recently to study the mechanical and thermal characteristics of rammed earth. 17However, to our knowledge, there are not yet sufficient studies on the tensile strength and the shear strength 18 of rammed earth. The tensile strength of rammed earth is neglected in general due to its very low value, but 19 in extreme conditions (e.g., seismic conditions), knowing the tensile strength is necessary for structural 20 design. Moreover, the shear strength is required in many cases to check the local failure of rammed earth 21 quickly, which has been observed in old structures (especially those submitted to concentrated loads). 22This paper presents experimental results on tensile strengths and the Poisson ratio of rammed earth 23 specimens. Local failure tests were also conducted on 1 m × 1 m × 0.3 m wallettes manufactured in the 24 laboratory. The shear strength was then identified using a simple method based on compressive strength, 25 tensile strength and Mohr's circle theory. The approach proposed was validated by tests on the wallettes. 26Finite Element (FE) modeling was also carried out to confirm the results. Last, the method presented was 27 validated for stabilized rammed earth lintels presented in the literature. 28

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In this paper we consider a two-degrees-of-freedom, non-linear model aiming to describe internal friction phenomena which have been observed in some modified concrete specimens undergoing slow dynamic compression loads and having various amplitudes but never inducing large strains. The motivation for the theoretical effort presented here arose because of the experimental evidence described e.g. in [94,24] in which dissipation loops for concrete-type materials are shown to have peculiar characteristics. Indeed, as (linear or nonlinear) viscoelastic models do not seem suitable to describe neither qualitatively nor quantitatively the measured dissipation loops, we propose to introduce a micro-mechanism of Coulombian internal dissipation associated to the relative motion of the lips of the micro-cracks present in the material. We finally present numerical simulations showing that the proposed model is suitable to describe some of the available experimental evidences. These numerical simulations motivate further developments of the considered model and supply a tool for the design of subsequent experimental campaigns.

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