An exact formulation for computing the critical buckling load of semi-rigid steel frames with tapered columns will be obtained. The presented methodology is based on the precise solution of the governing differential equations for elastic buckling of the uniform and non-uniform frames. These formulations also can be used for the tapered column with various support conditions. Moreover, the effect of tapered columns, with parabolic and quadratic functions for variation of the moment of inertia, flexibility of connections, and lateral support, such as bracing, on the equivalent buckling length factor of the frame will be studied parametrically as well as numerically. Comparing the findings with the available results indicates the accuracy, validity and capabilities of the proposed approach.

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