Failure analysis of cold drawn eutectoid steel wires for prestressed concrete

In this paper, a failure analysis of cold drawn eutectoid steel wires for prestressed concrete is presented. Results demonstrated that progressive cold drawing affects clearly the fracture performance of the materials, so that the most heavily drawn steels exhibit anisotropic fracture behaviour with crack deflection, i.e., a change in crack propagation direction which deviates from the original mode I propagation and approaches the wire axis or cold drawing direction, thereby producing a mixed mode stress state after a pop-in detectable in the load–displacement plot. An approximate procedure is proposed in the paper to estimate the fracture toughness of heavily drawn steels in both longitudinal (wire axis) and transverse (perpendicular) directions, on the basis of the critical load at the pop-in situation and at the critical failure instant (maximum load). In addition, a fracture criterion is proposed so that it can be used as a design criterion in real engineering situations involving prestressed concrete structures.