Application of External Magnetization EM Technique for Diagnosing Residual Prestress in Aged PSC Structures

The prestressed concrete(PSC) I-girder bridges are frequently applied to small and medium-sized bridges due to construction advantages. However, the prestress in PSC tendons is weakening due to various damages to the PSC bridges. To address this issue, this study aimed to develop a non-contact elasto-magnetic(EM) measurement system for the safety diagnosis of aged prestressed structures. This system aims to conduct safety diagnostics of aged PSC structures more efficiently and accurately, which previously relied solely on visual inspections. By doing so, it seek to secure core technology for the safety diagnostics of aging PSC structures, which is crucial in the current context of increasing aged PSC structures. First, it was conducted a theoretical verification of an external EM magnetization sensor with a Halbach array. Then it was examined its applicability through finite element analysis. The finite element analysis results demonstrated that sufficient magnetization reached the target location (the tendon) using external magnetization with a Halbach array, verifying the feasibility of estimating the prestress in the tendon.