This dissertation presents investigations into the behaviour of high strength
steel fibre reinforced concrete (HSFRC) slabs subjected to concentrated loads.
Improvement in the punching shear strength and ductility of slab - column
connections due to addition of high strength steel fibres is investigated.
Further, the validity and applicability of the upper bound plastic
theory of punching in HSFRC slabs is examined.
The experimental results obtained from one third model scale HSFRC slabs
show substantial increase in the ultimate punching shear strength with addition
of fibres. An optimum volume fraction of fibres of 0.5% is found to
transform the failure from sudden brittle failure to flexural - punching
failure and to enhance the ultimate punching shear capacity by approximately
70%. The upper-bound plastic theory is found to give fairly accurate
predictions of the ultimate punching shear capacity as long as the correct
efficiency factors of concrete are used.
Keywords: High strength concrete, steel fibres, punching shear,
ductility, plasticity theory, composite tensile strength, compressive strength,
fibre orientation factors, and length efficiency factors.