Structural Integrity Problems in Dual-Phase High Ductility Steel Bar

摘要

In EU regions with intense seismic activity imposing building code improvements like the EC2 and EC8-part3,introduced the use of high performance reinforced steel for example the dual phase B500c steel bar. In particularly earthquake-prone areas, like Greece has been over the past decade, the use of steel B500c is exclusively used in all structures from reinforced concrete. The present study focuses on investigating the mechanical behaviour of the material in the elastic region, through a series of mechanical tensile tests. In the elastic region of most of the steel specimens (15 pre-corroded and 5 non-corroded) a “knee” was observed which appears to be related to the localized detachment of the martensitic cortex from the core of the material. The interesting mechanical behaviour at the interface limit of the martensitic and ferritic-perlitic core on B500c steel bars, was further examined by performing (non destructive) ultrasound testing (C-Scan) and failure analysis using SEM, which led to the confirmation of the structural internal failure.