Cast-in-Place Concrete Box Construction Using Gang Formwork

[jar546]

I recently observed a large apartment project in Florida, where the entire structural system was built out of cast-in-place reinforced concrete. What stood out was the method: large steel gang forms, resembling container boxes, were craned into position to create one apartment “box” at a time. Concrete was poured in place, allowed to cure, then the forms were stripped and moved to the next unit.

The end result looks like a stack of concrete boxes, side by side and then above, until the building takes shape. Unlike slipforming, which is a continuous pour with moving forms, this system waits for curing between cycles. It is also different from precast modular construction, since every element is poured and finished on site.

The industry-standard description for this is:
Cast-in-place reinforced concrete box construction using large steel gang formwork, cycled floor by floor.

This method is often used on mid-rise apartment projects because it provides durability, fire resistance, and speed once the formwork system is in place. It also has implications for inspection, shoring, and sequencing since each “box” is structurally monolithic once cured.

Has anyone else seen this method used in your jurisdictions?

 

[RLGA]

Not in Arizona.

 

[jar546]

Not in Arizona.

I've only seen it once here in Florida, and never since. It was for an apartment complex of 564 new units split up into a bunch of 4-story buildings. That was the first time and last time I saw it used.

 

[ICE]

I used to build basement walls in Colorado. We used Simplex forms and I have never seen them used since. This video shows how they go together. They come in 8'& 10'. They start life out heavy and then soak up oil. When I first landed in Colorado Springs I went to the EDD office and asked for the worst job they have to offer.... the job that nobody wants or sticks with. My logic was that it would pay more than the easy jobs.

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[brokenkeys]

Tunnel form, or modular?

Tunnel form is great for mid-size apartments (short spans, fast construction, good for sound ratings, etc.), although I have yet to see an FHA compliant balcony slider that also meets windloads. Usually, they get around this by providing ramps to get over the threshold, or if the AHJ doesn't agree with that approach they use swing doors.

There's one developer/ builder that I know of that builds with modular concrete construction. 564 units in 4-story buildings sounds exactly like the sort of thing they've done all over Florida. Relatively plain, rectangular boxes. Not fancy, but very cost effective.

 

[RLGA]

I can understand its use in hurricane- or tornado-prone areas, and when all spaces are virtually the same size, such as an apartment or hotel.