Structural steel framing is an excellent system for providing building structures the ability to arrest collapse in the event of extreme damage to one or more vertical load carrying elements. The most commonly employed strategy to provide progressive collapse resistance is to use moment-resisting framing at each floor level to re-distribute loads away from failed elements to alternative load paths. Design criteria commonly employed for this purpose typically rely on the flexural action of the framing to redistribute loads and account for limited member ductility and overstrength using elastic analyses to approximate true inelastic behavior. More efficient design solutions can be obtained by relying on the development of catenary behavior in the framing elements and some designs have relied totally on catenary mechanisms. However, in order to reliably provide this behavior, steel framing connections must be capable of resisting large tensile demands simultaneously applied with large inelastic flexural deformations and the structure as a whole must be capable of distributing these large tensile demands through a complete load path. Research is needed to identify framing connection technologies capable of reliable service under these conditions.
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