Influence of Modal Mass Participation in Damage Detection of Cable Structures

Increasing applications of large diameter and long span cables as key structural components in cable supported structures are evident. However these cables accumulate damage over time during their life cycle and such damage needs to be detected to avoid the detrimental influences on the serviceability and ultimate capacity of the structure. In this context, vibration based damage detection (VBDD) methods have been used in some structures. Cable structures however exhibit complex vibration patterns namely with vertical, lateral, torsional and coupled modes which complicate the vibration based damage detection procedure. To address this matter, this paper proposes a new approach for detecting and locating damage in cables using component specific damage indices (DIs) based on the modal flexibility method considering the modal mass participation. Application of this new procedure is illustrated through two case studies: - (i) a suspended cable, and; - (ii) a three dimensional (3D) suspension bridge structure. Results verify that the DIs based on the lateral and vertical components of mode shapes, identified through their modal mass participation factors, are effective for detecting and locating damage in suspended cables and the main cables in a suspension bridge respectively, under a range of damage scenarios. Consequently, the research outcomes of this paper confirm that the modal mass participation factor is an important signature in damage detection of a structure using VBDD techniques.