Acoustic emission monitoring of strengthened steel bridges: Inferring the mechanical behavior of post-installed shear connectors

This study proposes an acoustic emission (AE) monitoring approach for old steel bridges strengthened with postinstalled shear connectors. In this strengthening method, cyclic traffic loads gradually fatigue the connectors and increase the bridge deflection at which the connectors engage in shear transfer. The key parameter that this study aims to estimate is how much the connectors need to slide before they engage in shear transfer. To estimate this parameter, this paper leverages the difference in AEs from shear connectors before and after they engage in shear transfer. Specifically, the b-value of AEs a k-mean clustering approach are used. To validate this novel approach, a full-scale, two-span steel girder with a concrete deck was used. The girder was strengthened with post-installed shear connectors and subjected to 20 cycles of sequential loads representing moving trucks. The results confirmed the effectiveness of the approach based on AE during the unloading of the girder.