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Strengthening and Rehabilitation

Strengthening and Rehabilitation 50.1 50.2 50.3 Introduction Lightweight Decks Introduction • Types • Case Studies 50 Composite Action Introduction • Applicability and Advantages • Types of Shear Connectors • Design Considerations 50.4 Improving the Strength of Various Bridge Members Addition of Steel Cover Plates • Shear Reinforcement • Jacketing of Timber or Concrete Piles and Pier Columns 50.5 Post-Tensioning Various Bridge Components Introduction • Applicability and Advantages • Limitations and Disadvantages • Design Procedures • Longitudinal Post-Tensioning of Stringers 50.6 F. Wayne Klaiber Iowa State University Developing Additional Bridge Continuity Addition of Supplemental Supports • Modification of Simple Spans. | Klaiber F.W. Wipf T.J. Strengthening and Rehabilitation. Bridge Engineering Handbook. Ed. Wai-Fah Chen and Lian Duan Boca Raton CRC Press 2000 50 Strengthening and Rehabilitation 50.1 Introduction 50.2 Lightweight Decks Introduction Types Case Studies 50.3 Composite Action Introduction Applicability and Advantages Types of Shear Connectors Design Considerations 50.4 Improving the Strength of Various Bridge Members Addition of Steel Cover Plates Shear Reinforcement Jacketing of Timber or Concrete Piles and Pier Columns 50.5 Post-Tensioning Various Bridge Components Introduction Applicability and Advantages Limitations and Disadvantages Design Procedures Longitudinal Post-Tensioning of Stringers 50.6 Developing Additional Bridge Continuity Addition of Supplemental Supports Modification of Simple Spans F. Wayne Klaiber 50.7 Recent Developments Iowa State University Epoxy-Bonded Steel Plates CFRP Plate Terry. J. Wipf Strengthening Iowa State University 50.8 Summary 50.1 Introduction About one half of the approximately 600 000 highway bridges in the United States were built before 1940 and many have not been adequately maintained. Most of these bridges were designed for lower traffic volumes smaller vehicles slower speeds and lighter loads than are common today. In addition deterioration caused by environmental factors is a growing problem. According to the Federal Highway Administration FHWA almost 40 of the nation s bridges are classified as deficient and in need of rehabilitation or replacement. Many of these bridges are deficient because their load-carrying capacity is inadequate for today s traffic. Strengthening can often be used as a cost-effective alternative to replacement or posting. 2000 by CRC Press LLC The live-load capacity of various types of bridges can be increased by using different methods such as 1 adding members 2 adding supports 3 reducing dead load 4 providing continuity 5 providing composite action 6 applying external post-tensioning 7 increasing