Robustness of Moment Resisting Steel-Concrete Composite Frames: The floor resisting mechanism in the case of column collapse

This paper illustrates the preliminary work carried on within a European Research Project, aimed at developing new design concepts for steel-concrete composite frames against accidental actions. Accidental actions can be resisted by residual strength and alternate load path methods. Combination of these strategies can lead to an effective and cost efficient design strategy for progressive collapse mitigation by redistributing the loads within the structure. The first part of the study investigates the behavior of two geometrically different steel-concrete 3D composite frames subjected to the loss of an internal column. Two full-scale experimental tests will be performed on a part of the structure, and the present paper presents the preliminary studies for the design of the tests. By simulating the total loss of the impacted column, the experiments enable investigation of the redundancy of the 3D slab system in terms of activation of membrane effects. Another important structural resource is the redundancy of the global structure through ductile joint design; this is a further major issue investigated by the project