How to predict the orientation factor of non-rigid macro-synthetic fibre reinforced concrete

Abstract

Polyolefin fibre reinforced concrete can met the requirements set in the standards that enable to consider the residual strengths in structural design. Such residual load-bearing capacity of fibre reinforced concrete is assessed by flexural tensile tests in which the presence of fibres can bridge the crack formed and provide strengths that are directly related with the number of fibres and their positioning in the fracture surface. Therefore, the orientation and distribution of the fibres is decisive in the mechanical behaviour of fibre-reinforced concrete and this can be estimated by means of the orientation factor. Several classical models have been extensively used for the case of rigid steel fibres. The increasing interest in structural synthetic fibres that can bend demands new considerations in this matter. A probabilistic model that considers the previous research with stereographical assumptions has been performed allowing the use of fibres that can bend. This study has developed significant tools for design with the aim of predicting such number of fibres crossing a vertical surface using fibre reinforced concrete with steel and polyolefin fibres. The model has been verified with experimental data and represents with accuracy the existence of boundaries, the type of concrete and compaction methods used to cast the moulds.