Analysis of Design Constitutive Model for Macro-synthetic Fibre Reinforced Concrete Through Inverse Analysis

Abstract

The increasing use of fibre reinforced concrete (FRC) as a structural material requires a constant development of new tools for design purposes. In this line, different codes and guidelines include constitutive models for FRC in their specifications. However, these constitutive models are usually based on the behaviour of steel fibre reinforced concrete (SFRC) and present several limitations on representing the full behaviour of macro-synthetic fibre reinforced concrete (MSFRC). With the aim of analysing the suitability of the constitutive models when applied on macro-synthetic fibres, an experimental program to determine the performance of MSFRC using different fibre contents and concrete mixes was performed. The study of the constitutive models was conducted through an inverse analysis using a two-dimensional analytical model to verify and compare the FRC constitutive equations of the MC2010 with the experimental results. The constitutive model of MC2010 was selected given that it is able to capture both the softening and hardening behaviour of FRC through a three-point constitutive equation. The results show that the original constitutive model of the MC2010 tends to overestimate the performance of PFRC. Moreover, it could be necessary to include an additional point on the post-cracking branch of the constitutive model to represent more accurately the full residual strength of PFRC. The results also show that the ultimate strain of the constitutive model should be extended to fully capture the performance of PFRC, especially for large deformations. This study suggests that it should be necessary to redefine the constitutive models through a new approach distinguishing between FRC blended with steel or macro-synthetic fibres.