This document discusses the effective length of columns, which depends on: 1) The end conditions of the column (fixed, hinged, or free) represented by the factor K. 2) Whether the frame is braced or unbraced. 3) The relative stiffnesses of the column to beams at each end, represented by factors G1 and G2. Formulas and charts are provided to calculate the buckling length factor K based on these parameters. An example problem demonstrates calculating K for three columns in a two-story frame.