Magnetic detection of prestressing steel fractures in prestressed concrete

Abstract

The paper deals with the remanent magnetism method (RM-method) to identify unsafe prestressed structures concerning sudden collapses of structural components due to fractures of the prestressing steel. It describes the non-destructive testing method that allows to localize fractures of single prestressing steel wires even in post-tensioned tendons. The method uses the magnetic field of externally magnetized tendons, measured at the concrete surface. The parameters that determine the characteristic fracture signal have been studied and are reported. The method has been successfully applied on full size units.