Development of finite element model for concrete filled steel beams in flexure

Abstract EN

The concrete-filled steel tube (CFST) can provide excellent earthquake resistant properties such as high strength, high ductility and large energy absorption capacity.

Steel-concrete composite beams have been extensively used in building and bridge construction.

Numerical simulation can often add value to costly experimental work.

Proper material constitutive models for concrete-filled steel tube (CFST) are proposed and verified by the finite element program ANSYS against experimental data.

In this analysis the material non-linearity for the steel casing (elasto-plastic model) and the concrete filling (cracking model), bond, contact and friction at the interface between the casing and the filling were considered.

In spite of not including the effect of steel casing local buckling in the current model, the model successfully predicted the member behaviour (section capacity and stiffness) when verified with the current available experimental data.

Techniques used for developing the model are presented along with the model verification.

Further developments for the model are outlined.

The cross sections of the CFST in the numerical analysis are square section, and square section strengthened by filling with normal mix concrete, quarry waste concrete.

Via the numerical analyses, it has been shown that for square CFST, the tubes can provide good confining effect.

The confining effect of the square steel tube is enhanced fully especially by filling.

Also it shows that the design methods of Eurocode-4 for in-filled concrete beams appear generally on the safe side.

The proposed design models provide a consistent and economical design procedure for simply supported composite beams.