15.02: Direct analysis of steel frames with non‐prismatic sections via tapered beam‐column elements

Abstract

ABSTRACTMembers with tapered sections are popularly used in contemporary structures for architectonic appearance, besides that, this is in the most optimal, economic and effective manner to use material to the actual requirement according to the section strength along the member length. This paper proposes a new design approach based on direct analysis method for steel frames with tapered sections, where the structural behaviours of members are accurately simulated via sophisticated non‐prismatic beam‐column elements with analytical formulations. Conventional method uses approximated assumptions for section properties along the member length, causing unreliable estimations on member stiffness and strength and usually bringing over‐conservative design results. To this, this research analytically expresses the flexural rigidity and sectional area for the stiffness and mass matrixes of an element, respectively. In order to directly reflect column buckling effects on the proposed element, a generalized imperfection shape‐function for tapered section is developed, where the imperfection shape function is expressed highly fitting the 1st Eigen‐buckling mode shape. Examples are employed to validate and verify the reliability, efficiency and accuracy of the proposed elements. The current research is believed to be a great contribution to the modern design of non‐prismatic members.