Investigations on Performance Evaluation of RC Beams Strengthened with Pre-fabricated Fabric Reinforced Concrete

Abstract

Fabric reinforced concrete investigated in this study is one type of textile reinforced concrete and they are gradually finding their place in Civil Engineering field due to their higher strength to weight ratio, corrosion resistance and in ammability. The aim of this study is to examine the performance of pre-fabricated fabric rein- forced concrete (FABcrete) as a strengthening material for beam. In this study, the efficacy of FABcrete as a strengthening material for beam is studied in terms of im- provement in load carrying capacity, ductility, crack pattern, failure behaviour. Characterization studies are essential to determine the mechanical characteristics of the pre-fabricated FABcrete towards using as a strengthening material. Therefore, uniaxial tension test of pre-fabricated FABcretes are carried out. FABcretes with three different volume fractions of fabric Vf of 0.8%, 0.72% and 0.6% are considered for testing under uniaxial tension. While performing the uniaxial test of thin concrete elements, it is difficult to maintain grip without failure. Therefore, analytical model is developed for predicting the uni- axial tensile behaviour of pre-fabricated FABcrete based on the experimental data. Model is developed for FABcrete consisting of cementitious matrix and an alkali re- sistant glass fabric (SRG-45). A combination of macromechanical laminate theory and damage mechanics is used for developing the model. Both fabric and matrix are considered as different plies. To predict damage, damage equation is developed as a function of volume fraction and strain. To update the stiffness matrix of undamaged FABcrete, damage value obtained from its developed equation is used. Equation for average crack spacing, which can be useful to know number of cracks at a particular load, is developed as a function of strain and volume fraction of fabric. The results of analytical model are compared with that of uniaxial tension experiment. Developed model is also useful in determining number of cracks present corresponding to particular strain and volume fraction. To examine the performance of RC beams strengthened with pre-fabricated FABcrete, experimental investigations are carried out. Volume fraction of fabric in strengthen- ing layer, rate of loading and adhesive for bonding of FABcrete with beam are the parameters varied for the beams. FABcretes with volume fractions of Vf 0.98% and 0.62% are examined for their e ectiveness towards strengthening. In some of the strengthened beams, cementitious matrix used in the FABcrete (called as FABmix) is applied as adhesive to ensure the bond between FABcrete and beam, and the remain- ing beams are strengthened with epoxy adhesive. To investigate the behaviour of FABcrete strengthened beam under high and low rate of loading, some strengthened beams are tested under 0.5 mm=min loading rate and remaining are tested under 2 mm=min. Mathematical modeling is carried out by developing numerical models for RC beams strengthened with pre-fabricated FABcrete using finite element software ABAQUS. Different methodologies are adopted and integrated for simulating FABmix bonded and epoxy bonded strengthened beams. Further, FABcrete strengthening layer is modeled as a laminate. In case of epoxy bonded beams, epoxy is modeled as a dif- ferent part by using cohesive elements. The overall study reported in this thesis proves the applicability of pre-fabricated FABcrete as a strengthening material.