1. ENG-1010 Lecture 16
Bridge Design

2. Table of contents What is a bridge.? Different types of bridges.
Descriptions.
History Working.
Culverts
Type of culverts
Depiction
References.

3. Bridge
Bridge is a structure built to span a valley, road, river, body of water, or any other physical obstacle.
Designs of bridges will vary depending on the function of the bridge and the nature of the area where the bridge is to be constructed.

4. Great Stone Bridge in China
History of Bridge Development
100 B.C. Romans
2,104 years ago
700 A.D. Asia
1,304 years ago
Clapper Bridge
Roman Arch Bridge
Tree trunk
Stone
Arch design
evenly distributes
stresses
Natural concrete
made from mud
and straw
Great Stone Bridge in China
Low bridge
Shallow arch
Allows boats
and water to pass
through

5. History of Bridge Development
1900
1920
Truss Bridges
Mechanics of Design
Wood
2000
Suspension Bridges
Use of steel in suspending cables
Prestressed Concrete
Steel

6. Basic Concepts
Span - the distance between two bridge supports, whether they are columns, towers or the wall of a canyon.
Force -
Compression
Tension
Compression –
Tension -
Concrete has good compressive strength, but extremely weak tensile strength. What about steel cables?

7. Basic Concepts Beam - a rigid, usually horizontal, structural element
Pier
Pier - a vertical supporting structure, such as a pillar
Cantilever - a projecting structure supported only at one end, like a shelf bracket or a diving board
Load - weight on a structure

8. Types of Bridges There are six main types of bridges: beam bridges
cantilever bridges
arch bridges
suspension bridges
cable-stayed bridges and
truss bridges

9. Bridge Design Engineering Considerations Ground conditions
Availability of materials
Aesthetic properties

10. Beam Bridges
Consists of a horizontal beam supported at each end by piers. The weight of the beam pushes straight down on the piers.
The farther apart its piers, the weaker the beam becomes.
This is why beam bridges rarely span more than 75m.

11. Box Girder Bridge Box shaped cross section Good in torsion
More expensive to maintain
Commonly precast

12. Segmented Bridge

13. Beam bridge
Forces
When something pushes down on the beam, the beam bends. Its top edge is pushed together, and its bottom edge is pulled apart.

15. cantilever bridges
A cantilever bridge is a bridge built using cantilevers: structures that project horizontally into space, supported on only one end.

16. Cantilever Bridge

17. Arch bridges The arch has great natural strength.
Thousands of years ago, Romans built arches out of stone.
Today, most arch bridges are made of steel or concrete, and they can span up to 800 feet.

18. Arch Bridges
Forces
The arch is squeezed together, and this squeezing force is carried outward along the curve to the supports at each end.
The supports, called abutments, push back on the arch and prevent the ends of the arch from spreading apart.

20. Suspension Bridges
This kind of bridges can span 800m to 2500m -- way farther than any other type of bridge!
Most suspension bridges have a truss system beneath the roadway to resist bending and twisting.

21. Forces
In all suspension bridges, the roadway hangs from massive steel cables, which are draped over two towers and secured into solid concrete blocks, called anchorages, on both ends of the bridge.
The cars push down on the roadway, but because the roadway is suspended, the cables transfer the load into compression in the two towers.
The two towers support most of the bridge's weight.

24. Cable-stayed Bridges
The cable stayed bridge is newer than the other types of bridge.
Large upright steel supports are used to transmit the load into the ground.

25. Cable Stayed Bridge

27. Truss Bridge Typical Span Lengths 40m - 500m World's Longest
Pont de Quebec
Total Length
863m
Center Span
549m
A Matsuo Example
2nd Mameyaki Bridge
All beams in a truss bridge are straight. Trusses are comprised of many small beams that together can support a large amount of weight and span great distances

29. Floating Bridge
Pontoon bridges are supported by floating pontoons with sufficient buoyancy to support the bridge and dynamic loads.
While pontoon bridges are usually temporary structures, some are used for long periods of time.
Permanent floating bridges are useful for traversing features lacking strong bedrock for traditional piers.
Such bridges can require a section that is elevated, or can be raised or removed, to allow ships to pass.

31. Culvert Basics
Must be large enough for volume of water….

32. Culvert
Hydraulically short conduit which conveys stream flow through a roadway embankment or past some other type of flow obstruction

33. Hybrid Bridges

34. Clyde Arc, Scotland

35. Think about Forces – Braking on High Speed Trains at 300km/h.

36. Bridge Construction

37. Onsite Construction
Cast onsite and jack
Use formwork

38. Precast Construction
Jacking sections
Precast deck panels

39. Building a Suspension Bridge

40. Building a Suspension Bridge

41. Use Temporary Works

42. Construction Process
Foundations(and Caissons)
Towers
Decks
Finishing

43. Make sure the calculations are correct!

44. Bridge Failure

45. Bridge in USA

46. Tacoma Narrows (USA)

47. Tacoma Narrows (USA)

48. Another failure in USA..