Byfield, M. P.
Crumple zone design for buildings.
In, COST Action TU0601: Robustness of Structures, Zurich, Switzerland,
04 - 05 Feb 2008.
Full text not available from this repository.
This paper proposes a modification to the limit state design approach that would improve the robustness of multi-storey buildings, as well as providing economies in the use of steel. Robust frames require relatively weak beams, but strong connections and columns. Limit state design may provide the reverse. The composite beams used in the majority of steel framed buildings are shown to possess a “hidden” reserve of strength. When subjected to the large sagging deformations associated with terrorist attacks, these beams are capable of resisting typically twice the design load. This creates a situation whereby the weak point in a frame can be transferred to either the connections or the columns, leading to non-ductile and potentially catastrophic failures in the event of severe overloading. To address this problem a systems approach is advocated, whereby ductile beams are designed to resist only working loads, albeit elastically. Thereafter the upper-bound flexural strength of beams is established. It is the corresponding upper-bound reactions that are used for the subsequent design of components lower down in the load path. This approach would improve robustness. It would also provide substantial economies in the use of construction materials.
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