Force Mechanism and Parametric Finite Element Analysis of Punching Shear Behavior of Flat Slabs with Welded Shear Reinforcements

Punching shear failure of flat slabs is a critical safety issue since it may occur without any prior signs of damage. Welded shear reinforcement fabricated by longitudinal chords and diagonal webs is proposed as a novel type of shear reinforcement to significantly improve punching shear strength and ductility of flat slabs. However, there are few investigations on its force mechanism at present. To compensate for the objective flaws in the experiment, this research uses ABAQUS finite element software to distinguish the influence of welded shear reinforcements on punching shear behavior of flat slabs. A nonlinear finite element model was developed and validated with experimental results. The failure mode, concrete stress, flexural reinforcement strain, and welded shear reinforcement strain are all investigated in failure mechanism of flat slabs. The webs of weld shear reinforcement can limit the development of cracks and strengthen the aggregate interlocking at the cracks. The parametric analysis of the welded shear reinforcement under different geometrical parameters proves that punching shear effect of diagonal webs of welded shear reinforcement is much larger than that of chords. The definition of the web shear reinforcement ratio provides a theoretical basis for the design of such punching shear keys.