Inelastic Behaviour of Hybrid Steel/Concrete Column-to-Flat Slab Assemblages

Abstract

The use of tubular columns in conjunction with reinforced concrete flat slabs provides structurally efficient solutions which avoid undesirable failure modes such as those associated with shear. This thesis is concerned with the development of a tubular column-to- flat slab connection system that enables reliable performance under seismic loading conditions. During this research a novel detail which features a gap around the column is proposed and developed; hence only the structural steel shearhead establishes the connection. The exposed parts of the shear arms (fuses) are designed to yield prior to punching shear failure, in a way that utilises the favourable features of steel in terms of the response to seismically induced loads. The proposed connection could serve as a primary lateral resisting system within all building configurations in regions of low to moderate seismicity or as a secondary system in areas of signi cant seismicity. In order to provide validation for the proposed details as well as associated numerical and design procedures, a purpose-built rig which is suitable for large scale testing of structural sub assemblages under combined gravity and uniaxial lateral loading, has been designed and constructed, and subsequently employed for a number of tests. Test results and numerical analyses are presented with respect to a conventional con guration, as well as for the proposed, partially embedded connection. The latter is shown to offer enhanced ductility compared with traditional forms. The results are used to demonstrate the favourable inelastic performance of the proposed detail in terms of ductility, low degradation effects and increased energy dissipation capabilities. Complementary small scale slab panel tests are also used to further optimise the composite behaviour of the proposed detail. Additionally, a closed form solution based on plastic limit analysis which can serve as a basis for a simplified design approach is proposed. Finally, the main findings from the experimental and analytical investigations are highlighted, and recommendations for future research are outlined