Shear behavior of prestressed steel-fiber-reinforced concrete hollow-core slabs

An experimental study was conducted to evaluate the effect of steel fibers on the shear strength of prestressed concrete hollow-core slabs. The main variables investigated were fiber volume fraction (0.38%, 0.5%, and 0.76%), slab thickness (12 and 16 in. [300 and 410 mm]), and shear span-to-depth ratio (3.0 and 3.5). The addition of steel fibers to 16 in. thick hollow-core slabs led to an increase in shear strength between approximately 55% and 90% compared with that of regular (no fibers) concrete hollow-core slabs. Furthermore, the 16 in. thick slabs with fiber volume fractions of 0.5% and 0.76% exhibited shear capacities above the nominal web-cracking shear strength calculated according to ACI 318-14. Alternatively, steel fibers led only to a relatively modest improvement, up to 30%, in the shear capacity of 12 in. thick slabs. The behavior of these slabs was significantly influenced by arch action, which led to substantial residual strength after diagonal cracking, regardless of the presence of fibers.