Inelastic behaviour of tubular column-to-flat slab connections

This paper is concerned with the behaviour of ductile shearheads for connecting reinforced concrete flat slabs to internal tubular steel columns. A novel detail is presented in which a gap is left around the column to enable the shearhead to yield in shear prior to the slab failing in punching shear. The proposed connection could serve as a primary lateral resisting system in low-rise buildings in regions of low to moderate seismicity or as a secondary system in areas of significant seismicity. Test results and numerical analyses are presented for a fully embedded ACI-type shearhead as well as the proposed partially embedded connection. The latter is shown to offer enhanced ductility compared with traditional forms. Experimental and numerical results are used to demonstrate the favourable inelastic performance of the proposed detail.

Research highlights
► Partially embedded shearheads provide favourable performance under cyclic loading.
► Shear arms can act as dissipative elements if a gap is left around the column.
► Dissipative elements should yield in shear prior to concrete failure.
► Dissipative elements provide high energy dissipation and stable hysteresis loops.