Quote:
Originally Posted by Ravenswood
In Chicago, residential high-rises are mostly reinforced concrete but office towers are mostly steel-framed.
Why is this so?
It’s not always the case. For example, 311 S. Wacker is a concrete office building. But it seems to be a general rule.
Some have suggested that concrete deadens noise better. But I’ve lived in concrete high-rises that are still plenty loud. I’ve also heard that steel offers larger floor plates for office uses.
Thoughts?
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Several reasons...
- Steel makes sense for offices because steel allows for a larger bay spacing that is more conducive to office layouts.
- Steel allows for easier reconfiguration for changing tenants over time.
- Steel more easily allows for the taller floor to floor height of office structures compared to concrete as the formwork takes more time to install when the floor to floor height is taller.
- Concrete allows for plumbing and electrical to be cast into the slabs which prevents the need for a full dropped ceiling and allows for a shorter floor to floor height than an office use, thereby saving cost.
- Post tensioned concrete is generally used in Chicago and allows for significant cost savings over traditionally reinforced concrete. This makes residential concrete structures more economical, but does not allow for offices to be concrete because post tensioned concrete cannot be easily cored through during future tenant buildouts. (311 S Wacker and 10 S - 30S Wacker are all traditionally reinforced concrete structures).
I'm sure others can expand on this list.