Out-of-plane shake table test of a rammed earth sub-assembly

Rammed earth construction is spread worldwide in new buildings and also as architectural heritage, representing a cultural identity that must be preserved. However, rammed earth heritage is also well known for its high seismic vulnerability and despite the increasing concern for this aspect, few experimental investigations were conducted so far on the seismic response of such structures due to the high required costs and complexity of the tests. Shake table tests are the most adequate to investigate the performance of a building; indeed, besides allowing direct observations, seismic tests consent to calibrate numerical models that can be later used to investigate the sensitivity of the structure to various parameters. In this framework, an experimental program was undertaken on a rammed earth mockup by means of shake table tests carried out at the National Laboratory of Civil Engineering (LNEC) in Lisbon. To investigate the out-of-plane behaviour of rammed earth walls, the mockup was built in full scale with a U-shape plan and then was subjected to a series of seismic inputs with increasing magnitude. The results are here discussed in terms of crack pattern, damage detection, peak displacements, base shear coefficient, hysteretic curve, and dissipated energy against ground motion parameters, such as peak ground values, cumulative absolute velocity (CAV), arias intensity (AI), input energy (IE), and specific energy density (SED). In conclusion, the model responded as a rigid block to earthquake simulations, and linear and quadratic correlations were found between the performance of the mockup and various of the seismic input parameters.This work was partly financed by FCT/MCTES through national funds (PIDDAC) under the ISISE Research Unit, reference UIDB/04029/2020, and by project PTDC/ECM-EST/2777/2014 (POCI-01-0145-FEDER-016737). The support from grant SFRH/BD/131006/2017 is kindly acknowledged. Thanks are also due to the Laboratory of Structures (LEST) of the University of Minho and to the companies JoAo Bernardino, Lda. and TERRACRUA-Construcoes Ecologicas Unipessoal, Lda for building the rammed earth model