Proposal for a simple method of structural calculation for ordinary earthen buildings in rural areas

In many parts of the world, especially in the rural areas, raw earth is a very common material for buildings. Nevertheless, the design of most of these constructions, even the most simple ones, are not supported by an adequate structural calculation due to the lack of data or appropriate tools. The outcome is the realization of structures wrongly dimensioned or, in some cases, the abandonment of raw earth in favor of more expensive materials but with inferior thermal characteristics and higher environmental impact. The aim of this work is to create a very simple tool for structural analysis, which can be used mainly in rural areas of developing countries, both for the construction of buildings and for the training of local technicians. The proposed method is an adaptation to the unfired clay brick masonry of methods specified in some international Standards for the simplified calculation of backed brick masonry. Adjustments to the methods to calculate backed brick masonry have been dictated by the diversity of the basic material. Other changes have been based on information collected on the technical literature, references taken by the topic relevant Standards and the direct experience of the authors. Two examples of application of the proposed method are shown, regarding two simple buildings located in a low-seismic site and in a seismic site with 0,05<ag*S≤0,25 (ag: peak ground acceleration, S: soil factor, both at the site). Examples demonstrate that the proposed method allows the construction of simple raw earth multi-storey buildings both in seismic and in not-seismic areas. The method is very simple so that it can be applied practically also by people with a basic technical knowledge.