The Church of the Nativity in Bethlehem has a narthex in the front that is as long as the façade of the Church and about six meters wide. Currently this narthex is covered by five cross vaults, three of which in a dangerous state of decay, and it is internally divided by three walls perpendicular to the façade, which appears to be strongly rotated outwards with a maximum horizontal top displacement of about 40 cm. Inside the central cross vault is heavily damaged and propped since the thirties of the last century. There have been numerous attempts over time to identify the causes of such a damage. Some archival researches, in-situ inspections of the subsoil and detailed laser scanner surveys, carried out during the recent restoration works in the Church and in the narthex, allowed to have a deeper insight into the construction features of the cross vaults and to put forward some hypotheses about the possible causes of the damage. This paper provides a scientific validation of these hypotheses by means of a finite element numerical simulation which tries to reproduce the deformation process of a three-dimensional simplified model of the narthex from an assumed initial configuration up to an ultimate state of damage, comparable with the current one. Such a model is discretized by means of tetrahedron elements obeying a damage plasticity law which exhibits a softening behavior in both tension and compression. The numerical simulations carried out provide some results that fit reasonably with the actual deformed configuration and can be considered as a useful tool for further insights.
FE non-linear approach to predict the structural damage of the Nativity Church Narthex
ALESSANDRI, Claudio;
2015
Abstract
The Church of the Nativity in Bethlehem has a narthex in the front that is as long as the façade of the Church and about six meters wide. Currently this narthex is covered by five cross vaults, three of which in a dangerous state of decay, and it is internally divided by three walls perpendicular to the façade, which appears to be strongly rotated outwards with a maximum horizontal top displacement of about 40 cm. Inside the central cross vault is heavily damaged and propped since the thirties of the last century. There have been numerous attempts over time to identify the causes of such a damage. Some archival researches, in-situ inspections of the subsoil and detailed laser scanner surveys, carried out during the recent restoration works in the Church and in the narthex, allowed to have a deeper insight into the construction features of the cross vaults and to put forward some hypotheses about the possible causes of the damage. This paper provides a scientific validation of these hypotheses by means of a finite element numerical simulation which tries to reproduce the deformation process of a three-dimensional simplified model of the narthex from an assumed initial configuration up to an ultimate state of damage, comparable with the current one. Such a model is discretized by means of tetrahedron elements obeying a damage plasticity law which exhibits a softening behavior in both tension and compression. The numerical simulations carried out provide some results that fit reasonably with the actual deformed configuration and can be considered as a useful tool for further insights.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
