Damage Localisation and Severity Evaluation of a Beam-like timber Structure based on modal strain energy and flexibility approaches

Abstract

Modal-based damage identification techniques have been widely used for structural damage evaluation. In nany cases, they were claimed to be successful in detecting, locating and quantifying of damage in structures. One of the popular and promising damage identification methods is the damage index method based on change of modal strain energy. However, systematic investigation on its capability and limitation in locating and quantifying damage is yet to be reported, especially structures with multiple damage. In this paper, after in-depth exploration of the capability and limitation of damage index and flexibility methods, a new hybrid algorithm, combining modified damage index and change in flexibility algorithms, is presented for damage localisation and severity evaluation. The study is based on finite element analysis (FEA) results of a timber beam. The mode shape was mass normalised and the mode shape curvature was normalised with respect to the maximum value of each considered mode. The first two flexural mode shapes were used in computing the algorithms. The aim of the study is to explore the capability and limitations of existing algorithms and present a new effective damage identification approach for locating damage and quantifying their severities. The numerical results indicate that the proposed hybrid algorithms based on modified damage index method and flexibility have greater advantages in detecting damage locations and evaluating damage severities, especially for multiple damage cases.