Disposable Knee Bracing: Improvement in Seismic Design of Steel Frames

Abstract

A new and practical technique of lateral bracing for single‐ and multistory steel frame construction is presented and discussed. Disposable Knee Bracing (DKB) technique, as it is called in this paper, is made up of two structural elements, the knee element and the diagonal brace element. The knee element is a fuse‐like element that dissipates energy by the formation of plastic flexural hinges at its ends and midspan when the building is subjected to severe lateral loads. The diagonal brace element, on the other hand, provides the required level of lateral stiffness and remains in the elastic range at all time. The knee element is a disposable beam element that can be replaced once its energy dissipation capacity is utilized. Standard limit analysis of low‐ and high‐rise steel frames are presented to demonstrate the advantages of the DKB against traditional bracing and eccentric bracing.