Determination of material parameters of a textile reinforced composite using an inverse method

A great diversity of different cement based fibre reinforced concrete (FRC) materials can be found today either in practical use or under development in research laboratories. The main goal of using fibres in a cement based matrix is to improve the ductility. A FRC is called a high performance material when the use of fibres leads to tensile strain hardening. This can only be obtained by using a fibre volume fraction which is exceeding the critical volume fraction. If so the fibres can ensure strength and stiffness at applied loads far exceeding the range in which matrix multiple cracking occurs. Textile reinforced cementitious composites with glass fibres as reinforcement exhibit relatively high strength and ductility and thus provide and interesting new material for construction purposes. The textile reinforced concrete (TRC) under study in this paper is essentially composed of two brittle materials. In this case a random distributed glass fibre textile is used in combination with an inorganic phosphate cement matrix. The material itself is characterised by a linear behaviour in compression and a non linear tensile behaviour. However, in order to design and optimize constructions it is not only necessary to develop effective analysis and design guidelines but also a method to obtain the necessary model parameters. In this paper an inverse method is presented to derive the model parameters which are normally obtained from a tensile test. The model parameters can be defined as the ultimate matrix stress and the efficiency of the fibres and matrix. The proposed inversed method uses the experimental force- deflection curves obtained from a four point bending test to derive the model parameters.

Publication year:2008

Keywords:TRC Textile Reinforced Concrete, GRC glasfibre Reinforced Concrete, inverse method