Q$3)(40$P$)$ For the following structure, determine the the base moment by

SRSS modal combination rule with the mode superposition method when

subjected to an earthquake defined with the following design acceleration

spectrum applied in the vertical direction. $=\%5.$

$w_1=0\mathrm{.}6987\sqrt[\phantom{2}]{\frac{EI}{m{L}^3}},w_2=1\mathrm{.}874\sqrt[\phantom{2}]{\frac{EI}{m{L}^3}}$

$\{{\}}_1=\{[1$

$2\mathrm{.}097]\},\{{\}}_2=\{[1$

$-1\mathrm{.}431]\}$