The reduced level of third floor of a building near a column is 205.350 m. The reduced levels of the undersides of four beams supporting the fourth floor framing into the column mutually perpendicular are 208.350 m, 208.450 m, 208.500 m and 208.550 m. The supported length of the column is
The distance between, rivet line and the nearest edge of a joint not exposed to weather, is taken (where t is thickness in mm of the thinner outside plate).