(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A 10 storey building has columns spaced on a 8m by 10m grid.

a) Calculate the reaction at the base of an internal column assuming a 300mm thick concrete floor slab and a live load of 3.0kPA (ignore self weight of column and assume concrete density 2.4t/m^3

b) Assuming an allowable axial stress of 20MPa in the reinforced concrete column estimate the size of column assuming a square cross section

2. Relevant equations

P=F/A

Volume * density = mass

3. The attempt at a solution

Well, I'm a bit confused by the wording of the question firstly.

So there is an 10 storey building with a concrete floor slab which is 8m by 10m with 300mm thickness right. So there is one column supporting this floor slab.

Firstly I calculated the mass of the slab which is 8 * 10 * 0.3 * 2.4 = 57.6tons

So the weight of that is 57600 * 9.8 = 564.48kN

So the column must support that + the live load.

Live load = 3000 Pa.

P= F/A

F=PA

F= 3000 * 8 * 10 / 1000 = 240kN

So total reaction force = 564.48kN+ 240kN = 804.48kN

Now there are no answers so I can't check this. Is this right?

b)

So is P = 20MPa

P = F/A

F= 804.48kN

A= 804.48kN/20MPa = .040224m^2

Sqrt(A) = 0.2m

So 0.2 by .02 m?

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# Homework Help: Structures question

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