Theoretical studies are presented on the prediction of strength of a wide flange beam-column in a multistory frame subjected to vertical and horizontal forces at the earthquake. P-Δ effects are taken into account of the column deflection itself and that of adjacent beams. Explicit expressions of the moment magnification factor are introduced as the function of dimensions of column and adjacent beams. If the adjacent beams are stronger than the column, the strength of the system is determined by the column strength, and vice versa. Proposed method shows a good agreement with precise numerical solutions.
