Reinforcement of Timber Elements in Existing Structures: State-of-the-Art Report of the RILEM TC 245-RTE (RILEM State-of-the-Art Reports, 33)

By presenting the work of the RILEM Technical Committee 245-RTE, the book provides an overview of the existing techniques for the reinforcement of timber elements, joints and structures. It consists of two parts: part I examines state-of-the-art information on reinforcement techniques, summarizes the current status of standardization, and covers STS, GiR, FRP and nanotechnology. In part II several applications of reinforcement are discussed: these include traditional structures, traditional timber frame walls, light-frame shear walls, roofs, floors, and carpentry joints. The book will benefit academics, practitioners, industry and standardization committees interested in the reinforcement of existing timber elements, joints and structures. RILEM Publications RILEM Proceedings (PRO) RILEM Reports (REP) Contents Reinforcement of Timber Elements in Existing Structures References Self-tapping Screws as Reinforcement for Structural Timber Elements 1 Introduction 2 Application 3 Mechanical Models 3.1 General 3.2 Mechanical Models for the Unfractured State 3.3 Mechanical Models for the Fractured State 4 Materials 4.1 General Remarks 4.2 Parameters Influencing the Steel Properties of Screws 4.3 Parameters that Determine Wood-Screw Composite Behaviour 5 Effect of Reinforcement on Shrinkage Stresses in Timber 5.1 General 5.2 Experimental and Analytical Investigations 6 Conclusions References Glued-in Rods as Reinforcement for Timber Structural Elements 1 Introduction 2 Properties of Glued-in Rods 2.1 Geometrical Properties 2.2 Material Properties 3 Mechanical Models 3.1 Strength Theory 3.2 Linear Elastic Fracture Mechanics Theory 3.3 Non-linear Elastic Fracture Mechanics Theory 4 Factors that Affect GiR Performance 4.1 Strength and Softening Behaviour of Adhesive 4.2 Relative Size and Stiffness of Rod 5 Design of GiR 6 Conclusions and Outlook References Fiber-Reinforced Polymers as Reinforcement for Timber Structural Elements 1 Introduction 2 FRP Materials 2.1 Fiber 2.2 Polymeric Matrix 3 FRP Reinforcement in Wood Structures 3.1 FRP Reinforcement Along the Wood Fibers 3.2 FRP Reinforcement Across the Wood Fibers 3.3 Repair of Damaged Structural Components 4 Long-Term Performance of FRP-Reinforced Wood Structures 4.1 Effect of Moisture 4.2 Effect of Temperature 4.3 Effect of Combined Moisture and Temperature 4.4 Effect of Exposure to Fire 5 In Situ Quality Control and Assessment of FRP-Reinforced Wood Structures 5.1 In Situ Quality Control for FRP and Wood Bonding 5.2 In Situ Assessment of Bonded FRP-Wood Structures 6 Outlook References Nanocomposites as Reinforcement for Timber Structural Elements 1 Introduction 2 Nanotechnology in Timber Reinforcement and Protection 2.1 Overview 2.2 Fire Resistance 2.3 Waterproofing 2.4 UV Protection 2.5 Abrasion Resistance 2.6 Biotic Decay 3 Reinforcement 4 Conclusions and Outlook References Reinforcement of Timber Structures: Standardization Towards a New Section for EC 5 1 Introduction 2 Approach to the Standardization Work 3 Organization of the Standardization Work 4 Work Items and Work Plan 4.1 General 4.2 Applications 4.3 Materials 5 Work Plan 6 Proposed Standard Structure 7 Contents of the Draft “Reinforcement” 7.1 General 7.2 Effects of Changes in the Moisture Content 7.3 Reinforcement of Double Tapered, Curved and Pitched Cambered Beams 7.4 Reinforcement of Notches 7.5 Reinforcement of Holes in Beams 7.6 Reinforcement of a Connection with a Tensile Force Component Perpendicular to the Grain 7.7 Reinforcement of Bolted/Dowelled Connections 7.8 Reinforcement of Members with Compression Stresses Perpendicular to the Grain 8 Conclusion and Outlook References Seismic Reinforcement of Traditional Timber Structures 1 Introduction 1.1 Seismic Response of Traditional Timber Structures 1.2 Earthquake-Resistant Features of Traditional Timber Structures 2 Considerations for Seismic Strengthening of Traditional Timber Structures 2.1 Considerations for Timber Components 2.2 Aspects to Be Considered for Seismic Reinforcement Design 3 Seismic Reinforcement Methods 3.1 Materials Used 3.2 Reinforcement at the Joint Level 3.3 Reinforcement at the Member Level 3.4 Reinforcement at the Structural Subsystem Level 3.5 Lessons from Past Interventions 4 Conclusions References Reinforcement of Traditional Timber Frame Walls 1 Introduction 2 Retrofitting of Traditional Timber Frame Walls (Experimental Experience) 2.1 Mechanically Fastened Plates 2.2 Near-Surface Mounted (NSM) Strengthening 2.3 Externally Bonded Reinforcement (EBR) Using Fibre-Reinforced Polymers (FRPs) 2.4 Self-tapping Screws 2.5 Timber-to-Timber 2.6 Mixed Interventions 3 Interventions on Infill 4 Discussion 5 Conclusions References Reinforcement of Light-Frame Wood Structures 1 Introduction 1.1 Background 1.2 Lateral Force Resisting System in Light-Frame Wood Buildings 1.3 Performance of Light-Frame Wood Structures During Earthquakes 2 Common Deficiencies of Light-Frame Wood Structures 2.1 Soft First Storey 2.2 Weak Diaphragm 2.3 Inadequate Load Path 2.4 Inadequate Connections 2.5 Geometric and Mass Eccentricities 2.6 Brittle Components 3 Standard Retrofit Techniques 3.1 Retrofit of Shear Walls 3.2 Retrofit of Diaphragms 3.3 Retrofit of Load Path 3.4 Retrofit of Structures with Eccentricities 3.5 Retrofit of Brittle Components 4 Assessment and Retrofit Guidelines and Solutions 4.1 FEMA P-807 4.2 FEMA P-50 and FEMA P-50-1 4.3 International Existing Building Code 4.4 ASCE/SEI 41 4.5 Seismic Retrofit Guidelines (SRG) 5 State-of-the-Art Retrofit Solutions 5.1 Retrofit Testing Program 5.2 Steel Special Moment Frame (SSMF) and Inverted Moment Frames (IMF) 5.3 Cross-Laminated Timber 5.4 Energy Dissipation Systems (Dampers) 5.5 Distributed Knee-Brace System 5.6 Shape Memory Alloy (SMA) Devices 6 Conclusions References Reinforcement of Historic Timber Roofs 1 Introduction 2 Causes of Damage to Timber Roofs (Pathology) 3 Reinforcement Methods 3.1 Reinforcement of Timber Roof Members 3.2 Reinforcement for the Overall Load-Bearing System of the Roof 4 Conclusions References Retrofitting of Traditional Timber Floors 1 Introduction 2 Performance and Requirements of Existing Timber Floors 2.1 Out-of-Plane Performance 2.2 In-plane Performance 3 In-plane Performance Retrofitting of Floors 4 Out-of-Plane Performance Retrofitting of Floors 4.1 Timber-to-Concrete Composites (TCCs) 4.2 FRP Retrofitting 4.3 Timber-to-Timber Composites (TTCs) 5 Conclusion References Reinforcement of Traditional Carpentry Joints 1 Introduction 2 Traditional Carpentry Joints 2.1 Taxonomy and Geometry 2.2 Failure Mechanisms 3 Reinforcement Methods 3.1 Objectives 3.2 Methodologies and Techniques 3.3 Case Studies 3.4 Performance Criteria and Applicability Areas 4 Conclusions References