Keywords: earthen buildings, adobe masonry, masonry modelling, static non-linear analysis.

Earth masonry composed of unfired clay bricks and earth mortar joints has been traditionally used for thousands of years. Adobe buildings constitute a significant part of the global building stock and an important feature of the international architectural heritage. Experience has shown that unreinforced adobe masonry construction has a relatively poor response to horizontal loading and is therefore prone to seismic damage.

The application of detailed or formal engineering procedures in the appraisal of mud-brick structures and the assessment of retrofitting measures is currently hindered, among others, by the absence of accurate computational methods that would account for the specific characteristics of unfired earth. Although over the last few decades the numerical modelling of conventional masonry construction has been studied in depth, adobe masonry has generally received limited attention. This is possibly as a result of its intrinsic complexity that derives from the natural randomness and inhomogeneity of earthen materials. The constitutive models applied or developed for the numerical analysis of masonry have not yet been studied in the context of earthen construction. In addition, the applicability of the finite element (FE) method in the structural evaluation of adobe masonry structural members and buildings has not been adequately investigated and no attempts have been made for calibrating and validating numerical models based on the outcomes of laboratory tests and field observations. Furthermore, the formulation of FE models is precluded as a result of the lack of adequate experimental data describing the properties of earthen materials and the structural behaviour of adobe masonry assemblages.

This paper examines the behaviour of earth masonry construction under compression and the structural response of adobe buildings to monotonic horizontal loading. Initially a FE model of an adobe masonry assemblage is developed and its behaviour during the implementation of compressive loading-unloading cycles is investigated. The formulation of the model is based on the concepts of homogenized material and isotropic elastic-plastic constitutive law, while all the required input parameters are derived from laboratory tests. The numerical results obtained with the commercial code ABAQUS CAE are compared with corresponding experimental data thus enabling the deduction of useful conclusions on the validity of the simulation procedure. Following this, the behaviour of an adobe masonry model building subjected to linearly increasing horizontal loading is evaluated with static non-linear analysis. The predicted response of the structure is studied and the outcomes of the FE analyses are presented and discussed. Comments regarding the accuracy of the numerical results are made and the technical challenges encountered when dealing with the FE modelling of earthen construction are noted. Furthermore, key issues that future research should address in order to allow for the efficient use of FE modelling in the analysis of adobe structures are identified.

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