Output-Only Dynamic Testing of Rameses II Colossus by Singular Value Decomposition

The oldest statue on earth—the $\mathrm{3,300}\text{-}\text{year}$ -old colossus—of Rameses II is going to be transported from a major square in downtown Cairo to a new more-preserving home approximately $30\mathrm{km}$ away. The process of moving the huge granite sculpture is very complicated and has to be thoroughly investigated and carefully planned in order to avoid damage to such a valuable piece of cultural heritage. Determination of the vibration properties of the colossus is of major importance in order to evaluate the effect of the expected excitations from the forthcoming processes. To this end, the application of the advanced modal testing technique serves the process in detecting and assessing the weaker critical regions of the old colossus. This study is the first step in an intended comprehensive modal testing program. The study provides understanding of the distinctions in the basic modal behavior of the historic colossus. It also gives an assessment for the level of vibration this invaluable colossus is currently exposed to. A three-dimensional (3D) finite-element model was built based on accurately surveyed geometry from the site. The solid modeling capabilities of the ANSYS software helped in modeling the complex 3D geometry. Model updating was performed based on the results determined from ambient vibration tests and observations from the site. The updated model correlated well with the vibration test results. It showed the existence of weak areas close to the feet and to the head-to-abdomen conjunction. It also pointed out the degrading of the granite material properties.