Extension of EC3-1-1 interaction formulae for the stability verification of tapered beam-columns

• Current approaches for the verification of non-uniform members are discussed.
• Ayrton–Perry type procedures are presented for tapered beams and columns.
• Interaction formulae of EC3-1-1 are adapted for tapered beam-columns.
• Numerical simulations covering in-plane and out-of-plane failure are carried out.
• Statistical analysis is performed indicating accuracy of the proposed method.

EC3 provides several methodologies for the stability verification of members and frames. Regarding tapered beam-columns, in EC3-1-1, the safety verification may be performed by the General Method. However, application of this method has been shown not to be reliable. On the other hand, the interaction formulae in EC3-1-1 were specifically calibrated for stability verification of prismatic members.Recently, Ayrton–Perry based proposals for the stability verification of web-tapered columns and beams, in line with the Eurocode principles for the stability verification of prismatic members, have shown to lead to a substantial increase of accuracy and to provide mechanical consistency relatively to application of the General Method. Such methodologies may be further applied to the existing interaction formulae.It is the purpose of this paper to propose a verification procedure for the stability verification of web-tapered beam-columns under in-plane loading by adaptation of the interaction formulae in EC3-1-1, validated through extensive FEM numerical simulations covering several combinations of bending moment about strong axis, My, and axial force, N, and levels of taper.