On the ductility of reinforced concrete slabs containing low ductility reinforcing steels

Welded wire fabric (WWF) is commonly used in reinforced concrete slabs. In Australia, such steel is classified as Class L - low ductility (ASINZS467 1-2001). Typically, the strain at peak stress (termed the uniform elongation) is less than 0.03 and the ratio of tensile strength to yield stress (0.2% proof stress) is in the range 1.03 to 1.10. A reinforced concrete slab containing low ductility steel usually fails 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 quite catastrophic, often with little or no warning. This paper presents experimental results of tests on several simply-supported and continuous one-way slabs, reinforced with WWF. The great significance of strain localization in lightly reinforced slabs and its adverse impact on the ductility of slabs containing WWF is also explored.