Standard rebar placement and reinforcement surrounds large openings in a one-way concrete slab. Openings greater than 1'-6" up to a 4'-0" maximum require diagonal #4 bars measuring 5'-0" in length for each layer of main reinforcement. Additional top and bottom reinforcement equal to half of the steel interrupted by the opening is placed at 3" on center each side, unless noted otherwise. Uninterrupted main bars run continuously past the opening, while interrupted top and bottom bars are hooked and extended into the supports at a typical distance of 1'-6" or 2'-0" depending on the opening geometry. Two #5 bars are provided top and bottom, positioned below the main reinforcement at the top and above the main reinforcement at the bottom.
42" LARGE OPENINGS 14" (2) #5 T&B TOP BELOW MAIN REINF, BOT ABOVE MAIN REINF #4x5'-0" DIAG FOR EA LAYER OF MAIN REINF HOOK T&B BARS UNINTERRUPTED MAIN BAR ADD T&B REINF EQ TO HALF OF THAT INTERRUPTED BY OPNG @ 3" OC ES UNO EXTEND ADDED REINF TO SUPTS SPAN 1'-6" TYP 2' - 0" GREATER THAN 1'-6" (4'-0" MAX) 1 TYPICAL ONE-WAY SLAB OPENING REINFORCING 42" LARGE OPENINGS 14" (2) #5 T&B TOP BELOW MAIN REINF, BOT ABOVE MAIN REINF #4x5'-0" DIAG FOR EA LAYER OF MAIN REINF HOOK T&B BARS UNINTERRUPTED MAIN BAR ADD T&B REINF EQ TO HALF OF THAT INTERRUPTED BY OPNG @ 3" OC ES UNO EXTEND ADDED REINF TO SUPTS SPAN 1'-6" TYP 2' - 0" GREATER THAN 1'-6" (4'-0" MAX) 1 TYPICAL ONE-WAY SLAB OPENING REINFORCING
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