Pr$.16\mathrm{.}16.($in SI units$)$

$16-16.$ Determine the react ions at the supports $(1)$ and $(4).$ Joints $(1)$ and $(4)$ are pin connected and $(2)$ and $(3)$ are fixed connected. Take $E=200$GPa,$I=300({10}^6)m{m}^4,A=9\mathrm{.}68({10}^3)m{m}^2$ for each member.

solve by frame stifnness method