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Introduction to Bridge Design Principles

Feb 11, 2025

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The Basics of Bridge Design

Introduction

  • Moderator: Brittany Harlow
    • Virtual learning course on bridge design
    • Session duration: 45 minutes + Q&A
    • Questions via Q&A button
  • Speaker: Gary Johnson, Director of Structure and Bridge Design at Timmons Group

Overview of Timmons Group

  • Headquartered in Richmond, Virginia
  • 16 offices across the U.S.
  • Over 700 staff
  • Full-service firm with 67 years of experience

Speaker's Expertise

  • Gary Johnson: 27 years of experience in all aspects of bridge projects
  • Experience with various clients: state, federal, local, and private

Key Topics Covered

  1. Forces in Bridge Design

    • Types of forces: tension, compression, shear, torsion, bending, buckling
    • Importance of understanding unbraced length for columns and beams

  2. Materials Used in Bridges

    • Concrete: great in compression
    • Steel: excellent in tension and compression
    • Wood and cables: specific uses

  3. Types of Loads

    • Dead Load: weight of the bridge and permanent fixtures
    • Live Load: vehicles, pedestrians, impact due to movement
    • Factors for safety: 1.25x dead load, 1.75x live load

  4. Bridge Anatomy

    • Superstructure, Substructure, Foundation
    • Span arrangements: simple vs. continuous spans

  5. Foundation Systems

    • Types: spread footings, piles (end bearing and friction), drilled shafts

  6. Substructure Components

    • Abutments: fully integral, semi-integral, conventional
    • Piers: wall pier, multi-column, hammerhead, straddle bent

  7. Superstructure Elements

    • Approach slabs, decks, joints
    • Types of beams: concrete, steel, timber, prefabricated

  8. Pedestrian Bridges

    • Increased clearance, safety considerations
    • Design elements: wind load, deflection criteria

  9. Design Considerations

    • Clearance (vertical/horizontal), potential for future widening
    • Waterway crossings: hydraulic considerations
    • Construction loads and processes

  10. Other Considerations

    • Load ratings, camber and deflections, fracture critical members
    • Safety inspections and ensuring bridge safety

  11. Aesthetics in Bridge Design

    • Importance of form following function
    • Use of materials, colors, and shapes to enhance visual appeal

Questions & Answers

  • Discussion on different specifications for bridge rebar: coated, uncoated, stainless steel
  • VDOT's preference for stainless or corrosion resistant steel due to long-term benefits

These notes provide a comprehensive overview of the key points covered in the lecture. They can be used as a study aid or reference guide for understanding the basics of bridge design.

Full transcript