2. FUNCTION OF A BRIDGEFUNCTION OF A BRIDGE
To connect twoTo connect two
communities which arecommunities which are
separated by streams,separated by streams,
valley, railroads, etc.valley, railroads, etc.
• Built in 1973Built in 1973
• Total length is 5000 ftTotal length is 5000 ft
Bosporus Straits BridgeBosporus Straits Bridge
at Istanbul, Turkey –at Istanbul, Turkey –
3. COMPONENTS OF A BRIDGECOMPONENTS OF A BRIDGE
• Deck or Slab:Deck or Slab: supported roadway on abridgesupported roadway on abridge
• Beam or Girder:Beam or Girder: A rigid, usually horizontal,A rigid, usually horizontal,
structural elementstructural element
• Abutment:Abutment: The outermost end supports on aThe outermost end supports on a
bridge, which carry the load frombridge, which carry the load from
the deckthe deck
• Pier:Pier: A vertical supporting structure, such as aA vertical supporting structure, such as a
pillarpillar
• FoundationFoundation
5. Small Span BridgesSmall Span Bridges (up to 15m)
Medium Span BridgesMedium Span Bridges (up to 50m)
Large Span BridgesLarge Span Bridges (50-150m)
Extra Large ( Long ) Span BridgesExtra Large ( Long ) Span Bridges (over 150m)
Classification according to SpanClassification according to Span
9. Large Span BridgesLarge Span Bridges (50 to 150m)
Composite Steel Plate Girder BridgeComposite Steel Plate Girder Bridge
Cast-in-place Post-Tensioned concrete Box GirderCast-in-place Post-Tensioned concrete Box Girder
Post-Tensioned Concrete Segmental ConstructionPost-Tensioned Concrete Segmental Construction
Concrete Arch and Steel ArchConcrete Arch and Steel Arch
10. Extra Large (Long) Span BridgesExtra Large (Long) Span Bridges
(Over 150m)
Cable Stayed BridgeCable Stayed Bridge
Suspension BridgeSuspension Bridge
11. Discussion on Classification According ToDiscussion on Classification According To
Structural ArrangementStructural Arrangement
•Main Structure Below the Deck LineMain Structure Below the Deck Line
•Main Structure Above the Deck LineMain Structure Above the Deck Line
•Main Structure coincides with the Deck LineMain Structure coincides with the Deck Line
12. Main Structure Below the Deck LineMain Structure Below the Deck Line
Arch BridgeArch Bridge
Masonry ArchMasonry Arch
Concrete ArchConcrete Arch
Inclined Leg Frame ArchInclined Leg Frame Arch
Rigid Frame ArchRigid Frame Arch
Truss-Arch BridgeTruss-Arch Bridge
Steel Truss-ArchSteel Truss-Arch
Steel Deck TrussSteel Deck Truss
13. Main Structure Above the Deck LineMain Structure Above the Deck Line
Suspension BridgesSuspension Bridges
Cable Stayed BridgesCable Stayed Bridges
Through-Truss BridgeThrough-Truss Bridge
14. Main Structure Coincides with theMain Structure Coincides with the
Deck LineDeck Line
Girder BridgeGirder Bridge
Slab (solid and voided)Slab (solid and voided)
T-Beam (cast-in-place)T-Beam (cast-in-place)
I-beam (pre-cast or pre-stressedI-beam (pre-cast or pre-stressed
Wide-flange beam (composite & non-Wide-flange beam (composite & non-
compositecomposite
Concrete Box (cast-in-place, segmentalConcrete Box (cast-in-place, segmental
& pre-stressed& pre-stressed
Steel Plate Girder (straight & haunched)
Steel box (Orthotropic deck)
20. TRUSS BRIDGETRUSS BRIDGE
Firth of Forth Bridge, ScotlandFirth of Forth Bridge, Scotland
• Typical span length
150 to 1500 ft
• World’s longest:
Pont de Quebec, Canada
with a center span of
1800 ft
27. RIGID FRAME BRIDGERIGID FRAME BRIDGE
•Girders and piers act togetherGirders and piers act together
•Cross-sections are usually I-shaped or box-shaped.Cross-sections are usually I-shaped or box-shaped.
•Design calculations for rigidDesign calculations for rigid
frame bridges are moreframe bridges are more
difficult than those of simpledifficult than those of simple
girder bridges.girder bridges.
28. ARCH BRIDGEARCH BRIDGE
• After girders, arches are the second oldest bridge type.After girders, arches are the second oldest bridge type.
• Arches are good choices for crossing valleys and riversArches are good choices for crossing valleys and rivers
• Arches can be one ofArches can be one of
the more beautifulthe more beautiful
bridge types.bridge types.
• Typical span lengthTypical span length
130 ft – 500 ft.130 ft – 500 ft.
• World’s longest:World’s longest:
New River Gorge Bridge, U.S.A. with a center span ofNew River Gorge Bridge, U.S.A. with a center span of
1700 ft.1700 ft.
Larimer Avenue Bridge, PittsburghLarimer Avenue Bridge, Pittsburgh
33. CABLE STAYED BRIDGECABLE STAYED BRIDGE
Normandie BridgeNormandie Bridge
• Continuous girder withContinuous girder with
one or more towersone or more towers
erected above in theerected above in the
middle of the span.middle of the span.
• From these towersFrom these towers
cables stretch downcables stretch down
diagonally and supportdiagonally and support
the girder.the girder.
• Typical span lengthTypical span length
350 to 1600 ft.350 to 1600 ft.
• World’s largest bridge:World’s largest bridge:
Tatara Bridge, JapanTatara Bridge, Japan
center span: 2900 ft.center span: 2900 ft.
Different to suspension the cable straightDifferent to suspension the cable straight
36. SUSPENSION BRIDGESUSPENSION BRIDGE
• Continuous girder withContinuous girder with
one or more towersone or more towers
erected above in theerected above in the
middle of the span.middle of the span.
• At both ends of theAt both ends of the
bridge, large anchors orbridge, large anchors or
counter weights arecounter weights are
placed to hold the ends ofplaced to hold the ends of
the cables.the cables.
• Typical span lengthTypical span length
250 to 3000 ft.250 to 3000 ft. Golden Gate Bridge, CaliforniaGolden Gate Bridge, California
43. Factors Describe a BridgeFactors 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.).
45. LOADS ON BRIDGESLOADS 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.
46. VEHICULAR DESIGN LOADS (HL 93)VEHICULAR DESIGN LOADS (HL 93)
• AASHTO – American Association of State Highway
and Transportation Officials
This model consists of:
• Design Truck
• Design Tandem
• Design Lane
47. 145 kN 145 kN 35 kN
4.3 to 9.0 m 4.3 m
9.3 N/m
DESIGN TRUCK
DESIGN TRUCKDESIGN TRUCK
48. 110 kN 110 kN
9.3 N/m
1.2 m
DESIGN TANDEM
DESIGN TANDEMDESIGN TANDEM
49. DESIGN PRINCIPLESDESIGN 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
51. CONCRETE BRIDGESCONCRETE 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
52. STEEL BRIDGESSTEEL BRIDGES
• Minimum construction depth
• Rapid construction
• Steel can be formed into any shape or form
• Predictable life
• Ease of repair and demolition
53. WOOD BRIDGESWOOD 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
54. Wood Bridge onWood Bridge on
Concrete AbutmentsConcrete Abutments
Three Span WoodThree Span Wood
BridgeBridge
56. COLLAPSE OF BRIDGESCOLLAPSE OF BRIDGES
• Poor design
• Inadequate stability of the foundation
• Fatigue cracking
• Wind forces
• Scour of footing
•Earthquake