Problem

Given is the following massless system

with stiffness and loading

\begin{equation*} \mathbf{K}= \begin{bmatrix} 2 & -1 & 0\\ -1 & 2 & -1\\ 0 & -1 & 1 \end{bmatrix}k, \quad \mathbf{f}= \begin{bmatrix} 1\\0\\0 \end{bmatrix}. \end{equation*}
  • Consider x_1 as active and x_2,x_3 as inactive dofs and perform the static condensation.
  • Check your results solving the full system.