Structural health monitoring and risk alarming in plate-girder bridges under uncertain temperature condition

Even significant damage may cause very small changes in structural characteristics, particularly for large structures. Furthermore, these changes may go undetected due to changes in environmental and operational conditions. In this paper, the temperature-driven variability on a combined structural health monitoring (SHM) system is examined in a model plate-girder bridge. The combined SHM system consists of global vibration-based technique and local electro-mechanical impedance(EMI) based technique. First, dynamic modal parameters of the test structure are measured before and after the occurrence of flexural cracks at various temperatures. Also, EMI signatures are sensed before and after the changes in support systems at various temperatures. Next, the risk of damage-occurrence in the structure is alarmed by statistical pattern recognition of the signals. Damage-induced changes in the sic, als are distinguished from temperature-driven uncertainty. The effect of temperature variability is also assessed to estimate the accuracy of damage detection.