Details of special reinforcement at the end supports of hollow-core precast concrete floor units with a cast-in-place concrete topping slab are discussed. This reinforcement is intended to prevent collapse of the floors in the event of inadequate seating lengths or imposed movements due to volume changes or earthquakes. Results from experimental tests in which a vertical load was applied to the hollow-core precast concrete floor units with a cast-in-place topping slab and special support reinforcement are also presented. Three types of special reinforcement were investigated with two types of test. In one test, the vertical load was applied when the support seating was zero; in the other test, the vertical load was applied after the precast floor unit had been pulled horizontally off the supporting beam. The special reinforcement was shown to be capable of supporting at least the service gravity loads in these extreme conditions, if well designed.
