Byfield, M.P., De Matteis, G. and Dinu, F.
Robust design of steel framed buildings against extreme loading.
In, COST Action C26: Urban Habitat Constructions under Catastrophic Events, Prague, Czech Republic,
30 - 31 Mar 2007.
Full text not available from this repository.
Robust frames subjected to earthquakes and other hazards such as explosions require relatively weak beams, but strong connections and columns. The reason is to avoid collapse of the structure without producing significant energy absorption, which is demanded by exceptional events like those under consideration in current paper. In particular, for earthquake design, when moment resisting frames are of concern, it is necessary to apply design rules aimed at obtaining dissipative collapse mechanisms of the structure, which re-quire the formation of ductile plastic hinges at the beam ends rather than in the columns (to avoid partial sto-rey mechanisms) as well as in the beam-to column connections (to avoid brittle failures). On the other hand, robust design due to explosion hazards has to be related to the capability of the structure to avoid progressive collapse due to the loss of a column. In such a case alternative load paths must be present if disproportionate collapse is to be avoided. These can be in for form of bracing systems, or more commonly, alternative load paths can be found through catenary action of the floor members. In this case the connections to the floor members must be designed to accommodate the large sagging deformations that develop in the beams. This creates an exceptional situation whereby the remaining part of the structure should be able to support such an overloading. Also for steel constructions, a robust structural design cannot be easily achieved, since there are several factors - including strain hardening, the routine supply of over strength steel and high rates of strain - that can cause a brittle behavior of some components, e.g. the beam-to-column connections, which have to be intended as key elements for achieving a successful design. These factors are investigated in this paper, pro-viding useful issues that can guide to a correct design of robust steel frames to avoid premature collapse due to extreme loading
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