Seyed Reza SEYEDI - M.Sc. Student of structural engineering,Shahrood University, Shahrood, Iran
Ali KEYHANI - Associate Professo r of civil engineering,Shahrood University, Shahrood , Iran
Hashem JAHANGIR - Ph.D. Student of structu ral engineering, Ferdowsi University of Mashhad, Ma shhad, Iran

In recent years, significant efforts have been devoted to developing non-destructiv e techniques for damage identification in structures. Damag e detection techniques based on modal testing rely on the fact that the occurrence of damage or loss of inteegrity in a structural system leads to changes in t he dynamic properties of the structure. In this paper, an energy index based on mode shapes and their deriv ative is applied to detect damage in reinforced concrete bea ms isintroduced. The effectiveness of the proposed methods is examined through analytical model on an RC beam. Results illustrate that the energy index is sensitive to damage, and the proposed method is simple and r obust in locating single or multiple damages in a structure.

energy index, mode shappe, modal strain, damage detection, damage sever ity