Post-fire properties of beam-slab specimens with different restraints on interior beams

This study investigated the influence of the vertical restraint of the interior beam and columns on the post-fire mechanical behaviours of four beam-slab specimens. Two vertical restraints and interior beams with and without a rigid vertical restraint were investigated. In addition, a numerical model was developed to analyse the load–deflection curves and membrane actions of the beam-slab specimens after exposure to fire. A plane equation and deflection parameter were proposed to predict the yield-line and ultimate loads of fire-damaged beam-slab specimens with different vertical restraints. The results revealed that, compared with the vertical restraint of the interior beam, the restraint of the columns has a greater effect on the ultimate loads of the beam-slab specimens after exposure to fire. Compared with the experimental and numerical results, the proposed elliptic equation method can be used to analyse the ultimate loads and membrane action distribution of the beam-slab specimens with different restraints of the interior beams.