7.4.1 Topping Slab
Precast concrete diaphragm elements are interconnected by a reinforced concrete topping slab.
The deficiency is in the ability to transfer shear from one element to another. Check the slab element interconnection and check the lateral load capacity of the vertical elements that resist horizontal force. Where the capacity of the diaphragm is less than 150 percent of the sum of the load capacities of the vertical elements and where connections can allow the diaphragm to fail in a brittle manner, the R values used in computing the seismic demand shall be consistent with those for brittle systems (not to exceed R = 2). Conforming buildings without a reinforced concrete topping slab shall be placed in SPC 4.