Performance of rammed earth subjected to in-plane cyclic displacement

Rammed earth structures are worldwide spread, both as architectural heritage and new constructions. Yet, rammed earth buildings present, in general, high seismic vulnerability. Despite the several studies conducted on the mechanical characterisation of rammed earth and on the numerical modelling of structural elements built with this material, further in-plane cyclic tests on rammed earth sub-assemblies are required to characterise their hysteretic behaviour. In this framework, an experimental program was conducted where cyclic in-plane tests were performed on a large-scale rammed earth wall. The geometry of the wall was defined to represent a sub-assembly commonly found in rammed earth dwellings from Alentejo (Southern Portugal). The wall was subjected to cyclic shear displacements with increasing amplitude, imposed in both positive and negative directions. To detect the dynamic properties of the wall and to assess the development of the structural damage, dynamic identification tests were conducted along the experimental programme. The results are analysed in terms of crack pattern, dynamic properties, displacement capacity, base shear performance and stiffness degradation. Further discussion is led on the dissipated energy, while a bi-linear and linear equivalent systems are proposed as simplified modelling approach. In conclusion, degradation of structural capacity was observed due to cyclic loads, while adequate energy dissipation and base shear coefficient were obtained.This work was partly financed by FEDER funds through the Operational Programme Competitiveness Factors (COMPETE 2020) and by national funds through the Foundation for Science and Technology (FCT) within the scope of project SafEarth-PTDC/ECM-EST/2777/2014 (POCI-01-0145-FEDER-016737). The support from grants SFRH/BD/131006/2017 and SFRH/BPD/97082/2013 is also acknowledged. Acknowledgments are addressed to the Laboratory of Structures (LEST) of the University of Minho, Joao Bernardino, Lda, and TERRACRUA-Construcoes Ecologicas Unipessoal, Lda for building the rammed earth model