New opening in concrete tilt-up panel.

[ivanga7]

I am designing a new opening (40 in. x 86 in. rough opening) in an existing concrete tilt-up panel. The panel is 35 ft. wide, 32 ft. high from finished floor, and roof line is at about 28 ft. from finished floor. I usually reinforce the panel with vertical HSS members going all the way to the roof on either side of the opening and a horizontal HSS spanning between them. However, due to space constraints, a full height HSS vertical member cannot be installed. How do you design the stiffeners when they don't span the entire length of the panel?

 

[jayrod12]

a +/- 4'x7' opening (door?) in that large of a panel may be grounds for a do nothing approach. A tilt-up wall that large may have more than enough capacity even if you cut the bars. The lifting stresses on something that big would be high and may have governed the design.

 

[ivanga7]

I just realized that the entire opening will fall within the "knockout" portion of the concrete panel. When this happens the panel does not have to be reinforced at all correct?

 

[DETstru]

Knockout areas are designed as if nothing is there. If it was actually designed that way, you can cut it out without negative consequences.

I don't think I'd be too concerned with a 3x7 door in a 35' wide panel even if it wasn't designed for it. Minimum steel is probably more than sufficient that close to the base of the panel (assuming this is a door).