Shear force‐deformation relationship of concrete‐filled square steel tube beam‐columns under monotonic lateral loading

This paper proposes a simplified multi‐linear model of a shear force‐deformation relationship for concrete‐filled square steel tube short to slender beam‐columns. To evaluate the behavior of short to slender beam‐columns with a single model, the column member is divided into elasto‐plastic part and an elastic part. For the elasto‐plastic part, the deformation at each point is calculated based on the bending moment‐curvature relation model proposed by the author and by employing a newly proposed evaluation formula for curvature magnification. Predictions from the model are found to agree approximately with the experimental results up to large deformations. The predicated deformation at all points agreed reasonably well with the experimental results for the square CFT column with an extensive buckling length and cross‐section ratio for beam‐columns from short to slender. Predictions from the proposed shear force‐deformation relationship model were found to agree approximately with experimental results.