Anchorage of Stirrups in a Thin Cast-in-Place Topping

c omposite construction involving precast concrete and cast-in-place concrete is used extensively in building construction today. Fig. 1 shows a typical case in which a precast inverted tee ledger beam, supporting precast double tee beams, is made composite with a thin topping slab cast on top of the precast members. Shear must be transferred across the interface between the top of the precast inverted tee beam and the cast-in-place concrete. In a case such as this, shear transfer reinforcement will usually be needed across the interface, If this reinforcement is to be effective, it must be anchored in the concrete on both sides of Synopsis Tests are reported of hook and loop stirrup anchorages in thin toppings cast against precast members. Variables included were stirrup size, topping thickness, topping concrete strength, rough or smooth interface, and tensile strain normal to the anchorage. It is shown that #3, #4 and #5 bar stirrups can be anchored in 3.0, 3.5 and 4 in. (75, 90 and 105 mm) thick, normal weight concrete toppings, respectively, if the topping concrete has a strength of at least 3000 psi (20.7 MPa).