What is the minimum reinforcing bar requirement for a slab-on-ground with turned down footings?

What is the minimum reinforcing bar requirement for a slab-on-ground with turned down footings?

• A. 1 # 4 Bar at Top of Footing
• B. 2 # 4 Reinforcing Bar in the Middle of the Footing
• C. 1 # 4 Reinforcing Bar in Top and Bottom of Footing
• D. 35 Reinforcing Bar at the Bottom of the Footing

Answer: (C)

When a slab-on-ground with turned-down footings carries load, the footing experiences bending that creates tension on both faces of the footing. Adding reinforcing bar in both tension zones helps control cracking and keeps the footing from cracking under service loads. A bar only at the top would leave the bottom vulnerable to cracking, while placing bars only in the middle doesn’t align with where the tension actually occurs. Using one #4 bar in the top and one #4 bar in the bottom provides the minimum practical reinforcement to resist those tension forces without being excessive.

When a slab-on-ground with turned-down footings carries load, the footing experiences bending that creates tension on both faces of the footing. Adding reinforcing bar in both tension zones helps control cracking and keeps the footing from cracking under service loads. A bar only at the top would leave the bottom vulnerable to cracking, while placing bars only in the middle doesn’t align with where the tension actually occurs. Using one #4 bar in the top and one #4 bar in the bottom provides the minimum practical reinforcement to resist those tension forces without being excessive.