Evaluation for the Damaged Structures of Notre-Dame de Paris: A way for a correct Reconstruction

An impressive fire devastated the cathedral of Notre Dame in Paris, one of the symbols of European architecture. The flames started from the scaffolding embracing the base of the spire on the cathedral roof. The fire blazed up in the church during the religious celebration on April 15th at 6:45 p.m. The fire enveloped abruptly the roof and the spire erected by Viollet-le-Duc in 1860. The collapse took place about 80 minutes around 8 p.m [1-3]. Today, the clamor is all around, the silence is in the heart. At the time of the present report, the causes of the catastrophe are still wrapped in a dense smoke, like the one generated by the burning “forest” as the roof structure was called. This is the figure of the disaster. The Cathedral’s inferno devastated a world treasure, prompting an outpouring of collective sorrow and soulsearching over whether to recreate the destroyed oak-framed roofing and spire or adapt the cathedral to the 21st century. In the present paper, an original evaluation of the residual strength taking into account the fire effect and the water saturation in the limestone after the extinguishing is considered. The residual strength ratio (RSR) and the compressive strength evolution (CS) are carefully evaluated for the injured structures. An estimation of the effective strength ratio of the Cathedral walls is estimated. At the same time, the proposed approach is based on the solution of an extreme adaptive structure (grid shell) able to offer a strong temporary shelter in a short time and allowing a careful work of documentation and restoration of the roof cathedral by an approach like “how it was and where it was”