Guideline ratios/values question. 1

[ibbo]

Hi,

I was wondering if there were any general aspect ratios used in determining the width of a reinforced concrete column to its height?

On a different note, what would the unit weight of a concrete office building be in psf? What about a steel office building?

Lastly, what's a common ratio steel area/total area ratio used when designing short columns?

Sorry for the many questions, I appreciate any input you guys have. Thanks.

Jon

 

[Ussuri]

Generally I would aim for stocky columns so the ratio of effective height to least lateral dimension does not exceed 15. Absolute minimum column size is usually 300mm x 300mm.

You need to be careful when using data which applies to the weight of a building, because each building is unique. There is no firm answer but the data I have suggests for small buildings foundation loads cane be roughly assessed using:

Steel clad steel frame 5-10kN/m2
Masonry clad steel frame 15-20kN/m2
Masonry clad concrete frame 20-25kN/m2

But I would take that with a pinch of salt.

The UK reinforced concrete code gives a minimum reinforcement requirement of 0.4% of the cross sectional area and a maximum of 4%. But exactly how much reinforcement you require depends on the load carried.