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

2. FUNCTION OF A BRIDGE
Bosporus Straits Bridge
at Istanbul, Turkey –
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. COMPONENTS OF A BRIDGE
Deck
Girder
Abutment
Pier

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
Chesapeake Bay Bridge, Virginia

7. Firth of Forth Bridge, Scotland
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. 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.
Larimer Avenue Bridge, Pittsburgh

10. 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.
Normandie Bridge

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.
Golden Gate Bridge, California

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. Basic Span Types
Simple Span
Continuous Span
Cantilever Span

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

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

18. DESIGN PRINCIPLES Resistance ≥ effect of the applied loads
Strength of the Member ≥ Factor of Safety x Applied Load
Allowable Stress Design (ASD):
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 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: Cost: $4.3 billion
Length: 12,828 feet Type: Suspension
Materials: Steel Span: 6,527 feet

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

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

30. THANK YOU