Behaviour and design of composite steel-concrete beams under combined actions

![CDATA[This paper considers the study of composite steel-concrete beams under combined actions. The behaviour of these members in pure flexure, and under the combined action of flexure and shear is generally well understood. However, less well understood is the behaviour of these members under combined flexure and axial force. These design actions need to be considered when composite beams are constructed as inclined composite beams and subjected to loads acting through the span. A numerical cross-sectional analysis has been developed to study the moment-curvature response of composite steel-concrete beams subjected to an axial force at the centroid of these beams in the presence of flexure. Numerical results were obtained rapidly on a computer. An interaction diagram of the composite steel-concrete beams under combined flexure and axial force was able to be obtained. Furthermore, a rigid plastic analysis has also been carried out to study the interaction between the axial force and the bending moment on these beams. Comparisons between the cross-sectional analysis and the rigid plastic analysis approaches have been made, in order to determine the suitability of the rigid plastic analysis to be used in routine design by structural engineers. Recommendations on the suitability of the design approaches, conclusions and further research are then provided which will result in both safer and more economic design of composite steel-concrete beams under the identified loading regimes.]]