Strain localization and its impact on the ductility of reinforced concrete slabs containing welded wire reinforcement

Welded wire fabric (WWF) is commonly used in reinforced concrete (r.c.) slabs. WWF is classified in Australia as Class L or low ductility reinforcement and, as such, the characteristic strain at peak stress (termed the uniform elongation) is not less than 0.015 and the ratio of tensile strength to yield stress (0.2% proof stress) is not less than 1.03. A r.c. slab containing low ductility steel usually fails in bending by fracture of the tensile reinforcement at the critical section, well before the concrete in the compression zone becomes overstressed, and the conventional understanding of ductile under-reinforced flexural failure is not valid. The failure is brittle and results in complete collapse of the span, often with little or no warning. This paper explores the collapse load behaviour of slabs containing WWF, highlighting the great significance of strain localization in lightly reinforced slabs and its adverse impact on ductility. The results of tests on several simply-supported and continuous one-way slabs reinforced with WWF are used to illustrate the discussion.