First exploratory study on dynamic characteristics of rammed earth buildings

Rammed earth construction is attracting a renewed interest throughout the world thanks to its “green” characteristics in the context of sustainable development. Several studies have been carried out to investigate this material and evaluate its durability along with its mechanical, thermal and earthquake capacities. This paper presents a study on the parameters needed for the seismic design of rammed earth buildings in accordance with current earthquake standards. First, the dynamic parameters of buildings such as natural frequencies and damping ratios–which were necessary to determine the equivalent static seismic force–were identified using in-situ dynamic measurements. Then, these experimental values were compared with the values calculated by empirical formulas suggested in Eurocode 8 to demonstrate that these formulas were applicable for the cases of rammed earth structures. Then, modeling was done to find a simple suitable model for rammed earth structures. Laboratory experiments were developed to measure the Poisson’s ratio which was necessary for the models. The results provided by the shear-beam model were close to that of in-situ experiments, which showed a shearing behavior of rammed earth structures. Elements which influenced the dynamic behavior of this structural type were also discussed. Understanding the dynamic characteristics of rammed earth structures will help engineers in their design of new rammed earth buildings but also in earthquake analyses of existing rammed earth buildings.