Most of the technical information I've seen regarding fibre-reinforced concrete comes from the fibre vendors themselves. They would be a good first port of call.
A quick Google yields the following learned paper, which may be of interest:
Neves, R.D. and Fernandes de Almeida, J.C.O.
Compressive behaviour of steel fibre reinforced concrete
Structural Concrete, Vol 6 No 1, 2005, pp 1-8