MODAL FLEXIBILITY-BASED DAMAGE DETECTION OF TRUSS BRIDGES: A CONCEPTUAL FRAMEWORK

This paper presents a conceptual framework to locate the damages and diagnose the type of damage. The proposed framework is based on flexibility difference method. The considered structural damages in the framework are categorized as the significant loss of section due to corrosion, cracks due to fatigue or fracture and interaction effect of corrosion-fatigue. The framework consists of a location specified damage index, which is determined by in-situ measurements of vibration modal parameters. The degree of damage is determined proportions to the magnitude of the damage index. The framework provides guidelines to locate the damage or deteriorated region for detailed investigation. A finite element simulation based approach is newly proposed to diagnose the type of damage. Initially paper presents the theoretical derivation of damage index based on flexibility difference. Then the methodology the locate the damages are discussed in detail. Finally, a new approach is proposed to diagnose the type of damage. The scope of this framework is limited to the steel/metal truss bridges. The proposed methodology is comprehensively discussed and is illustrated in a flowchart. The damages or deteriorations due to fully section loss of members, which are difficult to access for visual inspections, can be accurately located by the proposed conceptual framework.