Chapter 3 Table of Contents - fdot.gov

1 Bridge Maintenance Course Series Reference Manual i Chapter 3 Table of Contents Chapter 3 - Bridge Anatomy .. 3-1 Bridge Components and Elements .. 3-1 Introduction .. 3-1 Bridge Deck and Related 3-1 Structural Deck/Slab .. 3-1 Wearing Surface .. 3-2 Approach Slabs .. 3-3 Joints .. 3-4 Curbs and Sidewalks .. 3-5 Railing and Safety Features .. 3-6 Drainage .. 3-7 Superstructure .. 3-8 Beams/Girders .. 3-9 Timber Longitudinal Deck Superstructures .. 3-16 Trusses .. 3-17 Substructure .. 3-21 Abutments .. 3-21 Wingwalls .. 3-24 Piers .. 3-25 Caps .. 3-27 Piles .. 3-28 Columns .. 3-29 Footings .. 3-29 Structures Located in the Channel .. 3-29 Fender 3-29 Dolphins .. 3-30 Slope Protection .. 3-30 Spurs and Dikes .. 3-31 Bridge Types and Design Details.

2 3-32 Multi-Girder System Bridge .. 3-32 Bridge Maintenance Course Series Reference Manual ii Girder and Floorbeam Bridge .. 3-32 Thru-girder (Concrete and Steel) .. 3-33 Slabs .. 3-33 FRP Decks and Superstructures .. 3-34 Rigid Frames .. 3-34 Trusses .. 3-34 Arches .. 3-35 Culverts and Pipes (Concrete and Metal) .. 3-37 Introduction .. 3-37 Headwalls .. 3-37 Wingwalls .. 3-39 Box Culvert .. 3-40 Barrel/Pipe .. 3-41 Cable Supported Bridges .. 3-42 Ancillary 3-44 Chapter 3 Reference List .. 3-45 Bridge Maintenance Course Series Reference Manual iii Chapter 3 List of Figures Figure Major Bridge Components .. 3-1 Figure Steel Grid Deck .. 3-2 Figure Timber Plank Deck .. 3-2 Figure Composite Deck and Steel Superstructure Showing Wearing 3-3 Figure Approach Slab to Roadway Approach.

3 3-4 Figure Top View of an Armored Compression Seal .. 3-4 Figure Top View of a Finger Plate 3-5 Figure Leaky Joints Lead to Problems at Bearings and Pier Caps .. 3-5 Figure Bridge Sidewalk Using Stamped Concrete for Aesthetics and Concrete Curb .. 3-6 Figure End Termination of Metal Beam Guide Rail at Approach Transition .. 3-6 Figure Approach Guardrail Transition .. 3-7 Figure Example of an Approach Guardrail End Treatment .. 3-7 Figure Schematics of Several Superstructure Types .. 3-9 Figure Riveted I-girder (left) and Welded Plate Girder (right) .. 3-9 Figure Bearing Stiffener .. 3-10 Figure Intermediate Stiffeners .. 3-10 Figure Shear Studs Being Welded On .. 3-11 Figure Typical Concrete Beam / Girder Shapes .. 3-11 Figure Non-Prestressed Reinforced Concrete vs. Precast Prestressed Concrete.

4 3-12 Figure Typical Prestressed Concrete Girder Sections .. 3-13 Figure Segmental Precast Concrete Box Girder Bridge Examples .. 3-15 Figure Nail-Laminated Decks. Pre-Fabricated (left) and Site-Constructed (right) .. 3-17 Figure Schematic of Steel Truss .. 3-17 Figure Truss Components (Courtesy of ODOT) .. 3-18 Figure Typical Types of Timber Trusses .. 3-19 Figure Typical Types of Through Trusses .. 3-19 Figure Diaphragm (K-bracing) .. 3-20 Figure Four Basic Elements of a Steel Roller Bearing .. 3-20 Figure Elastomeric Bearing .. 3-21 Figure Schematics of Several Abutment Types .. 3-22 Bridge Maintenance Course Series Reference Manual iv Figure Abutment Supporting Superstructure End .. 3-23 Figure Example of a Shorter Abutment .. 3-23 Figure Example of an Integral Abutment .. 3-23 Figure Abutment Utilizing Mechanically Stabilized Embankments (MSE).

5 3-24 Figure Concept of MSE Abutment .. 3-24 Figure Example of a Wingwall .. 3-25 Figure Piers Support the Superstructure .. 3-25 Figure Solid Shaft Pier .. 3-26 Figure Solid Shaft Pier .. 3-26 Figure Column Pier .. 3-27 Figure Hammerhead Pier .. 3-27 Figure Concrete Cap as Part of Pile Bent Structure .. 3-28 Figure Lead-on Pile Driver .. 3-28 Figure Example of Pile Bents .. 3-29 Figure A Bridge Fender System .. 3-30 Figure Examples of Dolphins. Timber Dolphin (left) and Steel Pipe Pile Dolphin with Concrete Cap (right).. 3-30 Figure An Example of a Gabion Basket Serving as Slope Protection .. 3-31 Figure Riprap Used for Slope Protection .. 3-31 Figure Timber Multi-Girder Bridge .. 3-32 Figure Prestressed Concrete Multi-Girder Bridge .. 3-32 Figure 2-Girder Steel Bridge.

6 3-33 Figure Thru-girder Bridge .. 3-33 Figure Example of a Rigid Frame Bridge .. 3-34 Figure Deck Truss Bridge .. 3-35 Figure Through Truss Bridge .. 3-35 Figure Deck Arch Bridge .. 3-35 Figure Glulam Suspension Arch Bridge .. 3-36 Figure Glulam Deck Arch Bridge .. 3-36 Figure Culvert Structure .. 3-37 Figure Reinforced Concrete Culvert Headwall and Wingwalls .. 3-38 Figure Culvert End Projection .. 3-38 Figure Culvert Mitered End .. 3-39 Bridge Maintenance Course Series Reference Manual v Figure Culvert Skewed End .. 3-39 Figure Cast-In-Place Concrete Headwall and Wingwall .. 3-39 Figure Rigid Culvert .. 3-40 Figure Flexible Culverts .. 3-40 Figure Concrete Box Culvert .. 3-41 Figure Multicell Concrete Box Culvert .. 3-41 Figure Twin Concrete Pipe Culvert .. 3-42 Figure Main Elements of a Cable- Supported Suspension Bridge.

7 3-42 Figure Cable-Supported Bridge: Suspension Cables and Suspenders .. 3-43 Figure Types of Cable Stay Bridges. Fan (left). Harp (right).. 3-43 Figure Cable-Supported Bridge: Cable Stayed .. 3-43 Figure Steel Arch with Vertical (left) and Diagonal (right) Hangers .. 3-43 Figure Examples of Cable Cross-Sections .. 3-44 Figure Failed Ancillary Sign Structure .. 3-44 Bridge Maintenance Course Series Reference Manual 3-1 Chapter 3 - Bridge Anatomy Bridge Components and Elements This Chapter provides a general overview of bridge anatomy. For additional information, readers are encouraged to use the FHWA Bridge Inspector s Reference Manual (BIRM). The BIRM is referenced at the end of this Chapter . Introduction Those involved with bridge maintenance should have a good understanding of bridge anatomy, including the ability to identify and understand the function of the major bridge components and their elements.

8 Most bridges can be divided into three basic components (see Figure ): Deck Superstructure Substructure 197B Figure Major Bridge Components Bridge Deck and Related Elements Elements of the deck are described in the following sections. Structural Deck/Slab The deck is that portion of a bridge that provides direct support for vehicular and pedestrian traffic. The deck can be constructed from: Cast-In-Place (CIP) concrete Precast concrete Timber Steel plate Steel grating A combination of precast and CIP concrete The top flanges of side-by-side precast girders While normally distributing load to a system of beams or girders, a deck may also be the main supporting element of a bridge. The AASHTO Manual for Bridge Element Inspection uses slab to distinguish between slab bridges where the slab transfers loads directly to the substructure and decks which transfer loads to the superstructure.

9 Bridge Maintenance Course Series Reference Manual 3-2 A steel grid deck is shown in Figure Steel grid decks are popular for movable bridges since they are lighter in weight making them easier to lift. 5B Figure Steel Grid Deck Five basic types of timber decks are: Timber plank deck (shown in Figure ) Nailed laminated deck Glued-laminated deck planks Stressed-laminated decks Structural composite lumber decks 205B Figure Timber Plank Deck Wearing Surface The wearing surface of a deck is the riding surface for the traffic and is placed on top of the structural portion on the deck, as shown in Figure There are also wearing courses placed integrally with the structural slab, and then the deck is referred to as a monolithic deck. A wearing surface could be used as a sacrificial part of the bridge deck, perhaps milled off and repaved every few years to maintain a smooth surface.

10 Wearing surfaces can provide a barrier to protect the decks from road salts. The wearing surface could just be asphalt, but in that case a membrane might be placed in between the concrete and asphalt interface since asphalt is permeable. In other instances, a more impermeable material might be used. Bridge Maintenance Course Series Reference Manual 3-3 Figure Composite Deck and Steel Superstructure Showing Wearing Surface Materials used as wearing surfaces include: Plain concrete Modified concretes (polymers, latex, silica fume) Asphalt Asphalt with waterproofing membrane Gravel (tar stabilized or loose) Timber treads Thin bonded epoxy or methacrylate Approach Slabs Most bridge abutments are designed to have very little settlement. Approach embankments usually settle more than abutments.