Design strength of slender concrete-filled rectangular steel tubes

Simplified studies of the short-term behavior of concrete-filled steel tubes are described A procedure is then developed for calculating the axial strength of concrete-filled steel rectangular columns based on the intersection of the section strength envelope and the nonlinear loading line. The intersection point may be obtained graphically or by the solution of a polynomial equation. Predictions of strengths obtained from the numerical model am compared with independent test results, and good agreement is obtained By applying appropriate strength reduction factors for steel and concrete, the procedure may be deployed in a design mode for calculating design strengths.