Numerical modelling of concrete-filled rectangular tubular flange girders subjected to pure bending

A detailed study of the behaviour of concrete filled rectangular tubular flange girders (CFRFGs) is described in this paper. These are steel beams in which the top flange plate is replaced with a concrete-filled steel section, resulting in greater load-carrying capacity and lateral torsional buckling resistance compared with a regular steel beam of similar proportions. These are complex members and their behaviour is governed by several inter-related parameters which are studied and discussed herein. Using the Abaqus program, a three-dimensional finite element model is developed to investigate the flexural behaviour of simply supported CFRFGs. Using available experimental results; the computational model is validated and is then employed to study the influence of the most salient properties on the overall response. A simplified analytical model is presented based on a fundamental assessment of the behaviour, to predict the capacity of these types of section in a way that is suitable for designers. The results are compared to those from the finite element analysis and it is shown that the analytical model is capable of providing an accurate depiction of the behaviour and the capacity of bending moment.