................................................................................................................................ xi ACKNOWLEDGEMENTS ..................................................................................................... xiii NOTATION ................................................................................................................................ xv CHAPTER ONE INTRODUCTION ........................................................................................................................ 1 1.1 BACKGROUND ..................................................................................................................... 1 1.2 OBJECTIVES ................................... ; ........................................................ : ............................. 2 1.3 STUDY DESIGN ..................................................................................................................... 2 CHAPTER TWO LITERATURE REVIEW ............................................................................................................ 5 2.1 VARIOUS CONNECTIONS IN TIMBER STRUCTURES ................................................... 5 2.2 ADHESIVE BONDED STEEL CONNECTIONS IN TIMBER STRUCTURE ..................... ? 2.3 APPLICATION OF ADHESIVE BONDED STEEL CONNECTIONS ................................. 8 2.4 PREVIOUS STUDIES OF ADHESIVE BONDED STEEL CONNECTIONS .................... 13 2.4.1 Strength Properties of the Connection ............................................................................ 13 2.4.2 Fire Resistance ............................................................................................................... 19 2.4.3 Load Duration and Environment Effects ........................................................................ 19 2.5 BRIEF REVIEW OF ADHESION THEORY ....................................................................... 20 2.6 ADHESIVES AND ADHESIVE BONDING ........................................................................ 21 , 2.6.1 Basic CharacJ_~rist~cs of Epoxy Resin Adhesives .................................... : ...................... 22 2.6.2~ Epoxy Bonding to the Wood .......................................................................................... 23 2.7 CHARACTERISTICS OF WOOD AS AN ADHEREND RELATED TO ADHESIVE BONDING ........................................................................................................................... 25 2.7.1 Surface Roughness ......................................................................................................... 25 2.7.2 Time Dependent Behaviour ............................................................................................ 26 2.7.3 Environmental Effects .................................................................................................... 28 2.8 APPLICATIONS OF ANALYTICAL TOOLS .................................................................... 30 2.9 SUMMARY ........................................................................................................................... 30 vi CHAPTER THREE SHORT DURATION EXPERIMENTS .................................................................................. 33 3.1 OBJECTNES AND SCOPE ............................................................................................... 33 3.2 DESIGN OF THE EXPERIMENTS ..................................................................................... 34 3.2.1 Design Principles ........................................................................................................... 34 3.2.2 Factors Influencing the Strength of the Connection ...................................................... 34 3.2.3 General Considerations .................................................................................................. 35 3.2.4 Design of Experiment. One .............................................................................................. 36 3.2.5 Design of Experiment Two ............................................................................................ 38 3.2.6 Design of Experiment Four ............................................................................................ 38 3.3 MATERIALS ........................................................................................................................ 39 3.3.1 Timber ............................................................................................................................ 39 3.3.2 Epoxy ............................................................................................ .'.; .............................. 40 3.3.3 Steel Rods ................................................ :: ................................................................... 42 3.4 SPECIMEN PREPARATION ......................... , ..................................................................... 43 3.4.1 Cutting Scheme of Glulam Timber ................... : ............................................................. 43 3.4.2 Steel Rod Placement ...................................... : ............................................................... 48 3.4.3 Epoxy Injection Procedure ............................................................................................. 49 3.5 TESTING EQUIPMENT AND INSTRUMENTATION ...................................................... 49 3.5.1 Loading System .............................................................................................................. 49 3.5.2 Data Acquisition System ................................................................................................ 49 3.5.3 Tensile Load Measurement ............................................................................................ 50 3.5.4 Measurement of Displacement. ...................................................................................... 50 3.5.5 Software .......................................................................................................................... 50 3.6 DRY AND WET CYCLING ENVIRONMENT .................................................................. 51 3.7 EXPERIMENT PROCEDURE ............................................................................................. 53 3:8 RESULTS OF THE SHORT DURATION EXPERIMENTS ............................................... 54 3.8.1 Experiment One ............................................................................................................ 54 3.8.2 Experiment Two ............................................................................................................ 55 3.8.3 Experiment Four ............................................................................................................ 55 CHAPTER FOUR . ANALYSIS OF SHORT DURATION EXPERIMENTS ...................................................... 63 4.1 FAILURE MODES ............................................................................................................... 63 4.1.1 Definitions and Descriptions ......................................................................................... 63 4.1.2 Distribution of Failure Modes in the Experiments ........................................................ 67 4.1.3 Analysis of Failure Modes ............................................................................................. 70 vii 4.2 INFI.,UENCE FACTORS .................................. : ................................................................... 73 4.2.1 Environmental Effects .................................................................................................... 73 4.2.2 Effect of Steel Rod Surface Geometry .......................................................................... 74 4.2.3. Effects from Using Different Epoxies ........................................................................... 75 4.2.4 Effect of Different Embedment Length .......................................................................... 77 4.2.5 Effect of Different Bar Diameters .................................................................................. 81 . 4.2.6 Effect of Edge Distance .................................................................................................. 84 4.2.7 Effect of Different Hole Diameters ................................................................................ 86 4.2.8 Effect of Connection Reinforcement .............................................................................. 87 4.3 AN EMPIRICAL MODEL .................................................................................................... 88 4.4 ESTIMATION OF THE EMPIRICAL MODEL ................................................................... 92 4.4.1 Comparison of the Short Duration Experiment Result and the Model Prediction ......... 92 4.4.2 Application to Multiple Bar Connections ...................................................................... 95 4.4.3 Comparison of the Empirical Model with the European Formula ................................. 97 4.5 DISCUSSION AND CONCLUSIONS ................................................................................ 100 CHAPTER FIVE STRESS DISTRIBUTION IN THE CONNECTION: THEORETICAL MODEL ........... 103 5.1 BACKGROUND ................................................................................................................. 103 5.2 OBJECTNES AND SCOPE ............................................................................................... 104 5.3 FINITE ELEMENT MODEL .............................................................................................. 105 5.3.1 Parameters of the Model. .............................................................................................. 105 5.3.2 Basic Assumptions and Material Properties ................................................................. 106 5.3.3 The Finite