[en] Slim-floor beams which have the steel sections fully or partially integrated into the concrete slab
lead to a significant reduction of the construction height. Due to its flat lower surface, it provides
favourable solution for technical installation. According to EN1994-1-1, for composite beams
plastic moment resistance is assumed. In the case of slim-floor sections, due to the reduced construction
height by the integration of the steel beam in the concrete and its extended bottom
flange, a large compression zone height may be expected, thus concrete failure in the compression
zone may happen before reaching the plastic moment resistance Mpl,Rd. Here, strain limit resistance
becomes decisive. For design with partial shear connection, EN1994-1-1 provides the
partial shear diagram based on the plastic bending resistance Mpl,Rd which is not always suitable
for slim-floor beams. Based on strain limited method, the more suitable partial shear diagram of
different slim-floor beams can be developed. From parametric studies of different types of slimfloor
beams, the impacts of critical parameters on the design are highlighted, and the limitations
of the current plastic resistance based partial shear diagram are suggested. A simplified calculation
method for situation beyond the limitation are also proposed to guarantee an economical design
of those beams.
