Numerical simulation of the fracture behaviour of glass fibre reinforced cement A. Enfedaque, M.G. Alberti, J.C. Gálvez ⇑ , J. Domingo Departamento de Ingeniería Civil: Construcción, E.T.S I. de Caminos, Canales y Puertos, Universidad Politécnica de Madrid, c/ Profesor Aranguren, s/n, 28040 Madrid, Spain highlights  Cohesive crack models are suitable for modelling fracture processes of GRC.  Inverse analysis allowed the verification of constitutive relations of GRC.  The tri-linear softening functions showed the different material properties.  Structural design with GRC can be performed with increased safety margins. article info Article history: Received 10 May 2016 Received in revised form 31 October 2016 Accepted 21 December 2016 Keywords: GRC Numerical simulation Softening function Glass fibre abstract The exceptional mechanical properties that glass fibre reinforced cement (GRC) boasts are the result of the interaction of the fibres and the brittle matrix. While the cement mortar provides a remarkable com- pressive strength, the presence of glass fibres increases the material toughness under tensile and flexural stresses. In addition, the fracture energy is also enhanced due to the presence of the glass fibres that add a multiple cracking damage pattern and, hence, a large damaged surface. In order to provide available resources that may ease and widen the structural design of GRC, the assessment and verification of its constitutive relations is of high significance, given that such relations may reproduce the fracture beha- viour. In this study, the softening function of GRC under flexural tensile fracture tests in an in-plane dis- position has been obtained by combining numerical simulations with an inverse analysis. Such inverse analysis has been able to reach satisfactory results by varying the parameters that define the trilinear softening function proposed. The process started by means of an initial estimation of the values of the parameters. By iteratively modifying such values, a softening function capable of reproducing the fracture behaviour of GRC was found. The study shows that use of tri-linear softening functions reproduces with notable accuracy the fracture behaviour of three different formulations of GRC. The significance of this research lies in the provision of constitutive relations that can be used for future modelling and structural design, thus widening the feasible applications and reliability of GRC in the construction industry. Ó 2016 Elsevier Ltd. All rights reserved. 1. Introduction Glass fibre reinforced cement (GRC) has been extensively used in the building industry, especially since the first alkali-resistant fibres became available in the 1970s [1].That is to say, more than 40 years of practice have shown GRC as being suitable for a wide range of applications, from telecommunication towers [2], perma- nent formworks [3], and cladding panels [4] to sewers. In addition, it has also had certain ornamental uses. The use of GRC in these applications has been based not only on cost-reduction concepts and the final appearance of the structures, but also on the remarkable mechanical properties of the composite material. Indeed, GRC is one of the most representative examples of the util- isation of the best performance of its two constituent materials: glass fibre and the cement mortar matrix. Generally, such proper- ties are achieved by the union of a mortar cement matrix and a 5% volumetric fraction of chopped glass fibres. While the presence of the fibres contributes to improving the ductility and tensile and flexural strength of the material, the stiffness and the compressive properties are provided by the cement mortar [5]. It is worth noting that one of the reasons for the success and diversity of uses of GRC has involved the absence of any additional reinforcement in the elements. That is to say, the absence of steel rebar reinforcement allows GRC members to be manufactured to almost any shape and with only a 10 mm thickness. This both http://dx.doi.org/10.1016/j.conbuildmat.2016.12.130 0950-0618/Ó 2016 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: jaime.galvez@upm.es (J.C. Gálvez). Construction and Building Materials 136 (2017) 108–117 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat