根据《混规》第6.2.15条

柱截面面积： $A=200\times800+200\times800=320000mm^{2}$

$$ \rho = \frac {22 \times 254 . 5}{320000} = 1.75 \% < 3 \% $$

两方向计算长度相等，故绕弱轴（y 轴）承载力控制

$$ I = \frac {1}{1 2} \times 2 0 0 \times 8 0 0 ^ {3} + \frac {1}{1 2} \times 8 0 0 \times 2 0 0 ^ {3} = 9. 0 7 \times 1 0 ^ {9} \mathrm{mm} ^ {4} $$

$$ i = \sqrt {\frac {I}{A}} = \sqrt {\frac {9 . 0 7 \times 1 0 ^ {9}}{3 2 0 0 0 0}} = 1 6 8. 4 $$

$$ \lambda = \frac {l}{i} = \frac {1 6 0 0 0}{1 6 8 . 4} = 9 5 $$

查《混规》表6.2.15，得 $\varphi = 0.57$

$$ N \leq 0. 9 \varphi \left(f _ {\mathrm{c}} A + f _ {\mathrm{y}} ^ {\prime} A _ {\mathrm{s}} ^ {\prime}\right) = 0. 9 \times 0. 5 7 \times (1 4. 3 \times 3 2 0 0 0 0 + 3 6 0 \times 2 2 \times 2 5 4. 5) = 3 3 8 1 \mathrm{kN} $$

因此选（C）