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?