UNIVERSITÉ DE REIMS CHAMPAGNE-ARDENNE ÉCOLE DOCTORALE SCIENCES DU NUMÉRIQUE ET DE L’INGÉNIEUR (620) THÈSE Pour obtenir le grade de DOCTEUR DE L’UNIVERSITÉ DE REIMS CHAMPAGNE-ARDENNE Discipline : MATÉRIAUX, MÉCANIQUE, STRUCTURES Spécialité :MATÉRIAUX, MÉCANIQUE, STRUCTURES Présentée et soutenue publiquement par Manh Hung HO Le 23 Avril 2020 FLEXURAL PERFORMANCE OF HYBRID CFRP REINFORCED CONCRETE BEAMS Thèse dirigée par Alex LI JURY M Emmanuel FERRIER, Professeur, Université Claude Bernard Lyon 1, President Mme Fatma KHELOUI-TAOUCHE, Mtre de Conférences HDR, Université Mouloud Mammeri, Algerie, Rapporteur M Marc QUIERTANT, Chercheur-HDR, IFSTTAR, Rapporteur M Boussad ABBES, Professeur, Université de Reims Champagne Ardenne, Examinateur M Alex LI, Professeur, Université de Reims Champagne Ardenne, Directeur de thèse M Jean-Fabien BERTHET, Mtre de Conférences, Université de Reims Champagne Ardenne, Co-Encadrant Acknowledgement First, I would like to thank my supervisor, Professor Alex LI for his support and guidance throughout this research He has been a constant presence throughout my studies and was able to keep me motivated, challenged and productive at all times I would like to thank my co-advisor Dr Jean-Fabien BERTHET for his support to me during my research I would like to thank all the members of the jury, Professor Emmanuel FERRIER of the University of Claude Bernard Lyon 1, Professor Boussad ABBES of University of Reims Champagne Ardenne, Mme Fatma KHELOUI-TAOUCHE of the University of Mouloud Mammeri and M Marc QUIERTANT of IFSTTAR, for agreeing to participate in my thesis jury All this work would not have succeeded without the help of the people of the Laboratory of Civil engineering , which I have been able to work over the time of my study I would particularly like to thank you to M Jule ASSIH, M Patrick JUPILLAT for their help during my research in Laboratory I would also like to acknowledge my fellow graduate students and staff who I have known during my time, here at Reims University I express my thanks to my friends and all those friends who have supported me throughout my studies Grateful appreciation is extended to the ministry of high education, Viet nam, for awarding Scholarship throughout the whole period of the graduate study I also wish to acknowledge the Campus France for the support and the following entire study in France Last, I would like to thank my family for their prayers, their love, their belief in my potential and encouragement throughout my entire life HO Manh Hung Reims in March 2020 ii Abstract The study on strengthening or repairing reinforced concrete structures by bonding composite materials has been widely carried out for more than two decades The mechanical and physical advantages of flexural strength, shear strength, mechanical behaviour, durability and reinforcement efficiency have been well approved The methods of reinforcement by composite materials can be distinguished as internal reinforcement, external reinforcement and hybrid reinforcement In this work, the hybrid reinforced concrete beams were studied Reinforcement in bending is provided by steel and composite materials, CFRP plate Two bonding methods between the concrete surface and the CFRP plate surface are proposed: direct bonding and bonding using an epoxy resin layer In this study, three different series of hybrid-reinforced beams were used: a direct bond between the two materials, the second with an adhesive bond between the two materials and the last with a specific bond A new method was proposed in order to evaluate the shear strength between the concrete and the CFRP plate The mechanical performance of these beams, mechanical behaviour, failure modes, ultimate load, load corresponding to the first cracks in the concrete, load corresponding to the plasticization of the longitudinal steel and the influence of the adhesion between the concrete surface and the surface of the CFRP plate were analysed The numerical finite element method was also used to analyse the mechanical performance of the beams The results provide new knowledge on the mechanical advantages of hybrid reinforced concrete beams Keywords: strengthening, hybrid reinforced concrete, shear strength, mechanical behaviours, composite materials, ultimate load iii Performance en flexion des poutres en béton hybride CFRP armé Résumé Les études sur le renforcement ou la réparation des structures en béton armé par collage de matériaux composites sont largement effectuées depuis plus de deux décennies Les avantages mécaniques et physiques sur la résistance la flexion, la résistance au cisaillement, le comportement mécanique, la durabilité et l’efficacité du renforcement ont été bien approuvés Les méthodes du renforcement par les matériaux composites peuvent être distinguées comme le renforcement interne, le renforcement externe et le renforcement hybride Dans ce travail, les poutres en béton hybride armé ont été étudiées Le renforcement en flexion est assuré par les matériaux en acier et en matériaux composites, plaque en CFRP Deux modes de liaison entre la surface du béton et la surface de la plaque en CFRP sont proposées : liaison directe et liaison l’aide d’une couche de résine époxyde Dans cette étude, trois séries différentes de poutres renforcées hybrides ont été utilisées: une liaison directe entre les deux matériaux, la seconde avec une liaison adhésive entre les deux matériaux et la dernière avec une liaison spécifique Une nouvelle méthode a été proposée dans ce travail pour évaluer la résistance au cisaillement de l’interface entre le béton et la plaque en CFRP Les performances mécaniques de ces poutres, comportement mécanique, modes de rupture, charge ultime, charge correspondant aux premières fissures dans le béton, charge correspondant la plastification de l'acier longitudinal et l’influence de l'adhérence entre la surface du béton et la surface du CFRP plaque ont été analysés La méthode numérique par éléments finis a également été utilisée pour analyser les performances mécaniques des poutres Les résultats apportent de nouvelles connaissances sur les avantages mécaniques des poutres en béton hybride armé Mots-clefs : renforcement, béton hybride armé, contrainte au cisaillement, comportement mécanique, matériaux composites, charge ultime iv LIST OF CONTENTS INTRODUCTION Introduction Introduction (en franỗais) CHAPTER LITERATURE REVIEW 15 Literature review 17 1.1 General 17 1.2 Fiber reinforced polymer (FRP) material 17 1.3 Composite for construction 21 1.3.1 Structural behavior of composites as internal reinforcements 22 1.3.2 Hybrid reinforced concrete structures 24 1.3.3 Structural behavior of composites as external reinforcement 27 1.3.3.1 The externally bonded reinforcement (EBR) FRP method 27 1.3.4 1.4 The near surface mounted (NSM) FRP method 30 Bond strength model 32 1.4.1 Bond characteristics of FRP bars-concrete 32 1.4.1.1 Analytical model 32 1.4.1.2 Experimental model 35 1.4.2 1.5 Bond characteristics of FRP plates/sheets-concrete 36 Numerical analysis for bond strength 41 1.5.1 FRP plates/sheets-concrete model 41 1.5.2 FRP bars-concrete model 43 1.6 Finite element analysis 45 1.6.1 Concrete model 45 1.6.1.1 Concrete cracking model 45 1.6.1.2 Concrete plasticity model 47 1.6.1.3 Concrete damaged plasticity model 49 1.6.2 Reinforcement steel 51 1.6.3 FRP composites 53 1.7 Summary 54 CHAPTER MATERIALS 55 Materials 57 2.1 Introduction 57 v 2.2 Concrete 57 2.2.1 Compression test 57 2.2.2 Flexural test 58 2.2.3 Tensile strength test 58 2.3 Steel bars 59 2.4 Composite material 60 2.5 Resin Sikadur-30 60 2.6 Summary 61 CHAPTER EXPERIMENTAL STUDY 63 Experimental study 65 3.1 Introduction 65 3.2 Bond strength in shear between CFRP plate and concrete surface 65 3.2.1 Specimens 65 3.2.1.1 Preparation of CFRP plates 68 3.2.1.2 Fabrication of the formwork and placed CFRP plates 68 3.2.1.3 Installation of strain gauges 69 3.2.1.4 Casting concrete part 69 3.2.2 Test setup 70 3.2.3 Experimental results 71 3.3 Reinforced concrete beam with hybrid CFRP plate 75 3.3.1 Preparation of concrete beams test 75 3.3.1.1 Preparation of steel reinforcement and gluing strain gauges 77 3.3.1.2 Preparation of CFRP plates 78 3.3.1.3 Casting concrete 79 3.3.2 Test setup and instrumentation 80 3.3.3 Test results 81 3.3.3.1 Group of specimens 81 3.3.3.2 Group of specimens 87 3.3.3.3 Effect of bond type 92 3.4 Reinforced concrete beams with embedded CFRP plates 94 3.4.1 Preparation of concrete beams 94 3.4.2 Test results 96 3.4.2.1 Flexural loading 96 vi 3.4.2.2 Failure mode 97 3.4.2.3 Strain in concrete and steel reinforcement 98 3.5 Summary 99 CHAPTER NUMERICAL STUDY 103 Numerical study 105 4.1 Introduction 105 4.2 Finite element method 105 4.2.1 Abaqus software 105 4.2.2 Abaqus/Standard vs Abaqus/Explicit 106 4.2.2.1 Abaqus/Explicit 107 4.2.2.2 Abaqus/Standard (Implicit) 110 4.2.2.3 Choosing between implicit and explicit procedures 112 4.2.3 Abaqus/Explicit for solving a quasi-static problem 113 4.2.3.1 Loading rates 115 4.2.3.2 Smooth amplitude curves 115 4.2.3.3 Mass scaling 116 4.2.3.4 Energy balance 116 4.3 Materials model 118 4.3.1 Concrete damage plasticity (CDP) model 118 4.3.1.1 The flow rule and yield surface of CDP model 118 4.3.1.2 Material functions and parameters 120 4.3.2 Steel reinforcement model 123 4.3.3 Composite material model 124 4.3.4 Interaction between CFRP and concrete 124 4.4 FE modeling 126 4.4.1 Type of element 126 4.4.2 Geometry 127 4.4.3 Validation of the numerical model 128 4.4.3.1 Effect of the mesh size 128 4.4.3.2 Effect of the time period in Abaqus/Explicit 130 4.4.3.3 Effect of mass scaling in Abaqus/Explicit 131 4.5 Results and discussions 133 4.5.1 Load-displacement curves 133 vii 4.5.2 Failure mode and crack pattern 136 4.5.3 Strain in CFRP plates 137 4.6 Summary 138 CONCLUSIONS AND PERSPECTIVES 139 Conclusions and perspectives 141 Conclusions and perspectives (en franỗais) 145 References 149 Appendices 155 Appendix A Sika® CarboDur® Plates ( Type S1012) 156 Appendix B Sikadur®-30 158 List of Figures 163 List of Tables 167 viii ... the mechanical performance of the beams The results provide new knowledge on the mechanical advantages of hybrid reinforced concrete beams Keywords: strengthening, hybrid reinforced concrete, shear... Effect of bond type 92 3.4 Reinforced concrete beams with embedded CFRP plates 94 3.4.1 Preparation of concrete beams 94 3.4.2 Test results 96 3.4.2.1 Flexural. .. members of the jury, Professor Emmanuel FERRIER of the University of Claude Bernard Lyon 1, Professor Boussad ABBES of University of Reims Champagne Ardenne, Mme Fatma KHELOUI-TAOUCHE of the University