(Solved): 1) A column is to be made of a built-up I-shape section as shown below. The elements in the section ...

1) A column is to be made of a built-up I-shape section as shown below. The elements in the section are continuously welded together along the entire length of the column. The column will be braced laterally along its length such that is cannot fail in flexural buckling about either axis. It is torsionally pinned at the top and bottom. Determine the maximum height $L$ of the column such that it will fail simultaneously in global buckling and local buckling. Note: you do not have to solve for "L" explicitly; you may leave your solution in terms of a single equation and single unknown $\mathrm{L}$.