(Solved): 7. A reinforced concrete column 300mm in diameter is designed to carry an axial compressive load, ...

7. A reinforced concrete column $300\mathrm{mm}$ in diameter is designed to carry an axial compressive load, $\mathbf{P}=1000\mathrm{kN}$ as shown in Figure $\mathbf{Q}$ 7(a). Figure ${\mathbf{Q}}^7$ (b) shows the cross-section of the column at section $\mathbf{a}?\mathbf{a}$. Determine the required diameter of each reinforcing steel if the allowable stresses are $10\mathrm{MPa}$ and $120\mathrm{MPa}$ for the concrete and steel, respectively Use $E_{\text{camcrete }}=20\mathrm{GPa}$ and ${\mathbf{E}}_{\text{seed }}=200\mathrm{GPa}$. [Ans: $d_{\text{sted }}=28.8\mathrm{mm}$ ]