Analysis and design methods for fibre reinforced concrete: a state-of-the-art report

Report, 2007

During the past decades the concrete construction field has experienced a growing interest in the advantages fibre reinforcement has to offer. Of the different fibres available, e.g. steel, synthetic and glass fibres, the steel fibre is the most investigated and most commonly used. Fibre reinforcement today is mainly used in applications such as sprayed concrete, industrial floors and overlays, although other application areas exist. Some of the potential benefits from the adding of fibres to concrete are improved crack control and more slender constructions. The extent of the crack control depends on the amount of fibres added, and plays a great role for durability. As of today there exist no generally accepted design- and analysis procedures, and if the technique with fibres is to move forward, there is a need for development of such methods. Several technical committees have proposed design methods based on a stress-strain relationship, but also methods based on a stress-crack width relationship are proposed. Different methods for analysis of fibre reinforced concrete structural members are also proposed by several researchers. Comparison and evaluation of these methods, will provide a base for further research aiming at improvement of the, at the moment, available methods. It is found that for design, the Italian proposal provides a comprehensive method taking a step in the right direction considering the different ways of determining the characteristic length (for translating crack-width into strain). An improvement though, would be if the formula for calculation of crack width/crack spacing were to be modified according to a proposal made by Löfgren, see Gustafsson and Karlsson (2006). Regarding analysis, all the reviewed methods yield good results in comparison with experiments described in the reviewed articles.