The Narthex of the Church of the Nativity in Bethlehem: an integrated analysis for the interpretation of a structural damage

The Narthex of the Church of the Nativity in Bethlehem is about six meters wide and as long as the facade of the Church, approximately 24 m. It is covered by five cross vaults and internally divided by three walls perpendicular to the façade. The vaults have been since many years in a dangerous state of degradation and the façade wall appears to be strongly rotated outwards, with a maximum horizontal displacement at the top of about 40 cm. The central cross vault in particular is heavily damaged. There have been numerous attempts over time to identify the causes of such damage, but none of them has given until now a satisfying answer. Some restorations now in progress are giving significant contributions to a more precise insight into the construction features of the cross vaults and their effects on the walls. All such data allow to advance some hypotheses about the possible causes of the damage occurred. This paper aims at providing a finite element validation of such hypotheses by means of advanced non-linear dynamic analyses capable of reproducing the damage evolution up to the current configuration.