Shear strength of reinforced concrete flat slabs without shear reinforcement
The behaviour of slab column junction of reinforced concrete
flat slab structures, subjected to various combinations of vertical load
and moment, was studied. Two different failure modes were investigated,
(i) Shear failure.
The theoretical approach of the shear failure based on the
equilibrium of the internal forces in a slab and the compatibility of the
deformation of the concrete and steel. The failure criteria is assumed to
be the failure of a concrete cone under biaxial compression in the
compressive zone at the vicinity of the column faces. The analysis of the
flexural failure was achieved by studying the yield line patterns and using
the virtual work method. The theoretical method of analysis was applied
for internal columns and extended to the case of external columns.
To fill in the gap of available experimental data ten square
slabs of 5 ft. side lengths and three circular slabs of 5 ft, diameter, and
4 in. thick simply supported along the edges were specially designed and
tested under different combinations of axial load and bending moment. The
proposed analysis is applied to these slab tests and a comparison between
the observed and predicted failure loads is presented.
The theoretical analysis is applied to all other available
slab tests and compared with the experimental findings. Good agreement is
obtained between the test and calculated loads. A number of conclusions
are drawn from these comparisons as well as from the experimental
observations. Some suggestions are also made for further research on