An approximate theory of pseudo-arches

A pseudo-arch is a triangular door built at the bottom of a heavy wall of stone or bricks. It represents a revolutionary static device, introduced at the beginning of the Neolithic Age, for creating an entrance through a wall without compromising the stability of the structure. We here formulate and solve approximately the problem of constructing a pseudo-arch in terms of plane elasticity. We show that the geometric proportions of some ancient pseudo-arches seem to reflect the predictions of the elastic approximate solution.