Design of precast concrete framing systems against disproportionate collapse using component-based methods

EN 1992-1-1:2004 provides prescriptive rules for determining minimum tying requirements in concrete structures that are not designed for accidental actions. Physically, the tying requirements are intended to localise any accidental damage that might occur by establishing alternative load paths. A major limitation of the EN 1992-1-1:2004 tying rules is that they do not provide any quantifiable level of performance under accidental actions. This paper focuses on the design of precast concrete structures and their connections for prevention of disproportionate collapse under sudden column removal. A component-based method is used in which the structural system is replicated using beam-column elements, rigid links and springs. The proposed approach is demonstrated for the design of a novel D-Frame precast concrete system. Emphasis is placed on the design of a beam-to-beam half-lapped joint for the tying forces resulting from sudden column removal. Means of achieving the required connection strength and ductility are investigated with the latter proving most challenging. Directly the reinforcement ties in adjoining precast beams through couplers is shown to provide greater ductility than connecting beams through top and bottom steel plates bolted to vertical dowel bars embedded in the beams.