Plastic Design of Steel Arches

Abstract

The in-plane failure modes of steel arches range from the extremes of plastic collapse for stocky arches with significant bending actions to elastic buckling for slender arches in uniform compression. Between these extremes, failure involves an interaction between plastic collapse and elastic buckling which depends on the arch profile, support conditions, loading, and slenderness, and is influenced by geometrical imperfections and residual stresses. Few design codes give methods for designing steel arches against in-plane failure. The methods that are used are essentially based either on the buckling strengths of equivalent columns, or on the use of moment amplification or second-order elastic analysis and the attainment of a limiting stress. Any method based solely on elastic analysis and a limiting stress is necessarily conservative for stocky arches with negligible stability effects, since it ignores the often substantial redistributions that take place after first yield. This paper discusses the use of the method of plastic collapse analysis for the in-plane design of steel arches.