Structural Health Monitoring of Steel-Concrete Composite Beams Using Acoustic Emission

Steel-concretes composite structures have been widely used in buildings and bridges during the past decades. However, in the hogging moment regions of steel-concrete composite beams, the concrete slabs are vulnerable to cracks and the connection interfaces are subject to debonding and slip. These damages could substantially reduce the stiffness, strength and durability of the beams. Structural health monitoring of steel-concrete composite beams is thus of interest. In this study, acoustic emission (AE) is applied to detect and characterize damages in steel-concrete composite beams. The damage induced AE sources were located based on Akaike information criterion (AIC)and genetic algorithm (GA), where AIC helped to determine the arrival time of AE waves more accurately in the presence of noise and GA helped to find the optimal location considering AE waves received by all the sensors. With located AE sources, the damage size could also be estimated. After that, the crack types and orientations were diagnosed based on MTA. Through inversed four-point bending test, the proposed method was proved to be able to identify concrete cracks and steel-concrete debonding damages in steel-concrete composite beams with different sizes of headed studs. The beam with studs of lower shear capacity behaved with higher concrete crack resistance, and the dominant damage mechanism in the concrete slab was found to be tensile-mode cracks.