PSI - Issue 29

A. Boostani et al. / Procedia Structural Integrity 29 (2020) 79–86 Boostani et al./ Structural Integrity Procedia 00 (2019) 000 – 000

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act as independent wa lls. As a result, large cracks have developed in certa in areas of the perimeter wa lls and needed consolidation. Where the thickness of the wa ll is reduced, as in the case of the niches in each span, the masonry is mostly constituted by a thinner layer of rammed earth. In portions of the wa ll where the load of the dome is transferred downwards, twinned columns are inserted, Fig.1c, to a llow for the construction of the massive arches upon which the dome used to rest. The additiona l thickness of the wa ll in these sections is required to counteract the horizonta l thrust generated by the weight of the dome. The construction techniques of the northern wa ll seem to stand apart from the methods used in the southern and western wa lls. At the base of the wa ll, instead of rammed earth, mud brickmasonry was used.

(a)

(c)

(d)

(b)

Figure1. (a) plan (b), south view; (c) perimeter wall portion; (d) carved gypsum decoration

At present, it is evident that there is significant separation between the baked brick masonry on the interna l face of the wa lls and the rammed earth or mud brick masonry. This has resulted in large vertica l fractures between the materia ls across the full extent of the perimeter wa lls, including in areas where only rammed earth and mud bricks are juxtaposed. This crack pattern is consistent with fractures caused by motions resulting from the collapse of the domes and earthquakes. Wa lls origina lly built with sufficient thickness now seem inadequate due to the absence of constructive elements and structura l ties. If the height of these wa lls is further increased, as expected with the lowering of internal levels following the removal of accumulated debris, the danger of collapse increases.