BRIDGE DESIGN

1. BRIDGE DESIGN BY SAIF HAROON Post-Doctoral Research Associate Department of Civil & Environmental Engineering FAMU-FSU College of Engineering

2. Bosporus Straits Bridge at Istanbul, Turkey – FUNCTION OF A BRIDGE To connect two communities which are separated by streams, valley, railroads, etc. • Replaces a slow ferry • boat trip • Connects two continent • Built in 1973 • Total length is 5000 ft

3. COMPONENTS OF A BRIDGE • Deck or Slab: supported roadway on abridge • Beam or Girder: A rigid, usually horizontal, • structural element • Abutment: The outermost end supports on a • bridge, which carry the load from • the deck • Pier: A vertical supporting structure, such as a • pillar • Foundation

4. Deck Girder Abutment Pier COMPONENTS OF A BRIDGE

5. TYPES OF BRIDGES • Beam or Girder Bridge • Truss Bridge • Rigid Frame Bridge • Arch Bridge • Cable Stayed Bridge • Suspension Bridge

6. Chesapeake Bay Bridge, Virginia GIRDER BRIDGE • Typical span length 30 to • 650 ft • World’s longest: Ponte Costa • e Silva, Brazil with a center • span of 1000 ft

7. TRUSS BRIDGE • Typical span length • 150 to 1500 ft • World’s longest: • Pont de Quebec, Canada • with a center span of • 1800 ft Firth of Forth Bridge, Scotland

8. RIGID FRAME BRIDGE • Girders and piers act together • Cross-sections are usually I-shaped or box-shaped. • Design calculations for rigid • frame bridges are more • difficult than those of simple • girder bridges.

9. Larimer Avenue Bridge, Pittsburgh ARCH BRIDGE • After girders, arches are the second oldest bridge type. • Arches are good choices for crossing valleys and rivers • Arches can be one of • the more beautiful • bridge types. • Typical span length • 130 ft – 500 ft. • World’s longest: • New River Gorge Bridge, U.S.A. with a center span of • 1700 ft.

10. Normandie Bridge CABLE STAYED BRIDGE • Continuous girder with • one or more towers • erected above in the • middle of the span. • From these towers • cables stretch down • diagonally and support • the girder. • Typical span length • 350 to 1600 ft. • World’s largest bridge: • Tatara Bridge, Japan • center span: 2900 ft.

11. Golden Gate Bridge, California SUSPENSION BRIDGE • Continuous girder with one or more towers erected above in the middle of the span. • At both ends of the bridge, large anchors or counter weights are placed to hold the ends of the cables. • Typical span length • 250 to 3000 ft.

12. Factors Describe a Bridge • Four main factors are used in describing a bridge: • Span (simple, continuous, cantilever) • Material (stone, concrete, metal, etc.) • Placement of the travel surface in relation to the • structure (deck, through) • Form (beam, arch, truss, etc.).

13. Simple Span Continuous Span Cantilever Span Basic Span Types

14. LOADS ON BRIDGES • Permanent Loads: remain on the bridge for an • extended period of time (self weight of the bridge) • Transient Loads: loads which are not permanent • - gravity loads due to vehicular, railway and • pedestrian traffic • - lateral loads due to water and wind, ice floes, • ship collision, earthquake, etc.

15. VEHICULAR DESIGN LOADS (HL 93) • AASHTO –American Association of State Highway • and Transportation Officials • This model consists of: • Design Truck • Design Tandem • Design Lane

16. 145 kN 145 kN 35 kN 4.3 to 9.0 m 4.3 m 9.3 N/m DESIGN TRUCK DESIGN TRUCK

17. 110 kN 110 kN 1.2 m 9.3 N/m DESIGN TANDEM DESIGN TANDEM

18. Allowable Stress Design (ASD): Strength of the Member ≥ Factor of Safety x Applied Load DESIGN PRINCIPLES Resistance ≥ effect of the applied loads Load and Resistance Factor Design (LRFD): η ∑γiQi ≤ φi Rn Where, Qi = Effect of loads Rn = Nominal resistance γi = Statistically based resistance factor applied to the force effects φi = Statistically based resistance factor applied to the nominal resistance η = Load modification factor

19. MATERIALS FOR BRIDGES • Concrete • Steel • Wood

20. CONCRETE BRIDGES • Raw materials of concrete: cement, fine • aggregate coarse aggregate, water • Easily available • can be designed to satisfy almost any geometric • alignment, straight to curved • can be cast-in-place or precast • Compressive strength of concrete range from • 5000 psi to 8500 psi • Reinforced concrete and prestressed concrete

21. STEEL BRIDGES • Minimum construction depth • Rapid construction • Steel can be formed into any shape or form • Predictable life • Ease of repair and demolition

22. WOOD BRIDGES • Convenient shipping to the job site • Relatively light, lowering transportation and initial • construction cost • Light, can be handled with smaller construction • equipment • Approx. 12% of the bridges in US are wood bridges • Commonly used for 20-80 ft span

23. Wood Bridge on Concrete Abutments Three Span Wood Bridge

24. GIRDER CROSS-SECTIONS COMMONLY USED IN BRIDGES

25. COLLAPSE OF BRIDGES • Poor design • Inadequate stability of the foundation • Fatigue cracking • Wind forces • Scour of footing • Earthquake

26. Before Collapse After Collapse

27. AKASHI KAIKYO BRIDGE, JAPAN Completion Date: 1998 Cost: $4.3 billion Length: 12,828 feet Type: Suspension Materials: Steel Span: 6,527 feet

28. SUNSHINE SKYWAY BRIDGE, USA Completion Date: 1987 Cost: $244 Million Length: 29,040 feet Type: Cable Stayed Materials: Steel, Concrete Span: 1200 feet

29. NEW RIVER GORGE BRIDGE, USA Completion Date: 1978 Cost: $37 Million Length: 4,224 feet Type: Arch Materials: Steel Span: 1700 feet

30. THANK YOU