Stability of steel-concrete composite beams with full openings in concrete flange

To satisfy the building structure requirements, floors must be cast with openings in certain structures; therefore, composite steel-concrete beams with full openings in their concrete flanges are designed. Such beams may experience a buckling problem caused by the lack of global or local stability of composite beams subjected to positive moments arising because of the full concrete flange openings. An elastic finite-element model is established to analyse the stability of composite steel-concrete beams with full concrete flange openings. Based on FEA and the Rayleigh-Ritz energy method, a section deformation function is assumed. Equations for calculating the critical buckling load of composite steel-concrete beams with full openings in their concrete flanges are derived. Next, parametrical analysis is carried out. Finally, the requirement of global and local stability of composite beams with full concrete flange openings is verified in a practical design example.