Robustness analysis of 3D Composite buildings with semi-rigid joints and floor slab

Analysis of composite building structures has been performed mostly on skeleton frames or on plane frame (2D) without the presence of composite slabs and semi-rigid joints. This is because detailed modelling of non-linear behavior of steel-concrete composite joints and the floor slab is rather tedious and involves other structural components including interaction between floor beams with slab and beam-to-column joints. This paper proposes simplified composite slab and composite joint models, which can be easily incorporated within a commercial software for the analysis of three-dimensional composite building frames with less computational time. The steel concrete composite slab is modelled by representing the profile metal deck by rows of rebars with equivalent areas and the profile concrete slab is converted into an equivalent uniform concrete section. The semi-rigid composite joints in the building framework are modelled using the Eurocode's component model represented by axial and rotation spring connectors. The proposed simplified models have been verified against the established test and numerical data available in the literature and found to be accurate enough for analysing 3-D composite frames with less computational time. The robustness of moment frames and simple braced frames was then investigated under a column loss scenario. The incorporation of semi-rigid joints and composite slabs in 3D frame analysis tends to produce more realistic estimate of large scale steel-concrete composite frames subjected to accidental loads.