Experimental study of rectangular CFST columns subjected to eccentric loading

To study the behavior of rectangular CFST columns subjected to eccentric loading, a total of 17 rectangular CFST columns uniaxial and biaxial bending tests were carried out. Concrete compressive strength, steel strength, cross-sectional proportion and eccentricity were selected as the variables to be investigated. The relationship between the load and the lateral displacement at the mid-height of the columns in the directions of both the strong and weak axes and the relationships of load versus end shortening for each specimen were duly recorded. The influences of the constraining factor and eccentric ratio in relation to the strength and ductility indexes of the specimens were investigated. Moreover, in order to achieve the ultimate bearing capacity of the relative rectangular hollow sections with a load of the same eccentricity, the rectangular hollow section models were established by means of the FEM. The concrete contribution ratio necessary for the rectangular CFST columns to be able to resist the eccentric loading was obtained also through comparison of the simulated results and the test data. Finally, based on the definitions and conclusions obtained for the design strength of rectangular CFST columns relying on the “Technical specification for design of steel structure dwelling houses in Tianjin” code (DB 29-57-2003), a factor β was proposed to enhance the steel strength in order to take into account the concrete contribution to the resistance. The modified equation can subsequently provide improved understanding and a more accurate predictive ability or value.

► Uniaxial and biaxial bending tests.
► The concrete contribution ratio for RCFST columns.
► A factor β was proposed to enhance the steel strength.