Seismic behavior of composite connections — flexural capacity analysis

Based on the experimental results of connections composed of concrete-filled square steel tubular columns and steel–concrete composite beams with interior diaphragms or anchored studs, the flexural capacity of connections is studied theoretically in the present paper. Analytical models are proposed, with consideration of the effects of axial load, concrete slab, middle interior diaphragm, beam and column width condition, and punching shear failure mode. Formulae in different conditions are established based on these models. The predictions and the test results are compared and they are in good agreement.