Combined footings are reinforced with top bars and bottom bars to address curling in which direction?

Combined footings are reinforced with top bars and bottom bars to address curling in which direction?

• A. Short direction
• B. Long direction
• C. Both directions
• D. No curling

Answer: (A)

Curling in concrete footings comes from restrained shrinkage and temperature effects, which make the section bend and edges lift or warp. In a rectangular combined footing, the bending and resulting curvature are most pronounced across the short axis, where end moments from the column reactions concentrate. Placing reinforcement on both faces—top and bottom—gives tensile resistance where the concrete tends to crack as the footing curls along that short direction, helping keep the footing flat. The long direction tends to curl less in this setup, so the emphasis is on controlling curling across the short span.

Curling in concrete footings comes from restrained shrinkage and temperature effects, which make the section bend and edges lift or warp. In a rectangular combined footing, the bending and resulting curvature are most pronounced across the short axis, where end moments from the column reactions concentrate. Placing reinforcement on both faces—top and bottom—gives tensile resistance where the concrete tends to crack as the footing curls along that short direction, helping keep the footing flat. The long direction tends to curl less in this setup, so the emphasis is on controlling curling across the short span.