A novel damage detection method in beam-like structures based on the relation between modal kinetic energy and modal strain energy and using only damaged structure data

Abstract

Dynamic damage detection methods, in which changes in the dynamic properties of structures such as frequencies and mode shapes are used to identify the location of damage, are generally based on the comparison between damaged and undamaged states of structures. In this study, a damage detection method in beam-like structures is introduced in which the location of damage is determined using only dynamic data of damaged structure. In this method, in the constituent elements of a beam, the absolute difference value between a coefficient of the modal strain energy of one element and a coefficient of the modal kinetic energy of the same element or another element of that beam is introduced as an indicator of the damage location. These coefficients depend only on displacement, rotation, and the element length of damaged structure; they are independent of data such as mechanical properties and geometrical characteristics of the cross section. Thus, this method does not require any mechanical and geometric data from the damaged structure or the base model; it only needs modal displacements and the length of damaged beam elements. Satisfactory capability of the proposed method in detecting damage is presented using finite element model of damaged beams with diverse geometries and boundary conditions. The results of dynamic tests performed on an existing damaged reinforced concrete bridge and the experimental model of a damaged steel cantilever beam are also used to validate the proposed method.