2. TABLE OF CONTENT
โข Introduction about Bridge
โข Types of Bridges
โข Cantilever Bridge
โข History of Cantilever Bridge
โข Types of Cantilever Bridge
โข Method of Bridge Construction
โข Advantages of Cantilever Bridge
โข Disadvantages of Cantilever Bridge
โข Case study- Wilson Creek Bridge, South west Virginia
โข Form Traveller System
3. INTRODUCTION
โข A bridge is a structure built across an obstacle such as a body of water, valley
or road for the purpose of providing a passage over the obstacles.
โข Design of the bridge varies depending on the function of the bridge and the
nature of the terrain where the bridge is to be created.
5. CANTILEVER BRIDGE
โข A bridge built using cantilever structures that projects horizontally into space,
supported on only one end.
โข There are some special conditions where the number of supports cannot be
given, in that case, Cantilever Bridges are suitable
โข For small footbridges, the cantilevers may be simple beams; however large
cantilevers bridges are designed using trusses.
โข Cantilever bridges should be able to resist tensile stresses in the upper
support and the compressive stresses in the lower support.
6. CANTILEVER BRIDGE (CONTD.)
โข In some cases the length between two supports where Bridge has to be
constructed it is very long which cannot be spanned by one cantilever on
each side.
โข In such a situation, the special Beam Bridge or truss Bridge is placed between
the arms of two cantilever which connects them into one Bridge. The type of
bridge is known as Suspended Span Bridge.
7. HISTORY OF CANTILEVER BRIDGE
โข First cantilever bridge appeared in 19th century when there was a need for
longer bridges.
โข To solve the problem of length, engineers of that time found out that many
supports would distribute the loads among them and help to achieve length.
โข The one to be the first to invent and patent a cantilever bridge was Heinrich
Gerber which did it in 1866.
โข Hassfurt Bridge over the Main River in Germany.
8. TYPES OF CANTILEVER BRIDGES
On the basis of method of construction
โข Balanced Cantilever Bridges
โข Continuous Cantilever Bridges
9. TYPES OF CANTILEVER BRIDGES (CONTD.)
โข Balanced Cantilever Bridges
โข most efficient methods of building bridges
โข It does not require false work for construction.
โข This method has great advantages as compared
to other forms of construction in urban areas,
โข where temporary shoring will disrupt traffic and
services
โข In the deep valleys below and on waterways
where false work are not only costly but also a
hazard.
10. TYPES OF CANTILEVER BRIDGES (CONTD.)
โข Balanced Cantilever Bridges
โข Construction begins at the permanent piers
and proceeds mid-term in a balanced
manner as shown in fig.
โข The structure is hence self-supporting at all
stages.
โข The construction may either be cast-in-situ
or can be precast.
11. TYPES OF CANTILEVER BRIDGES (CONTD.)
โข Continuous Cantilever Bridges
โข The bridge was constructed using
two gantries from the opposite end
(abutments) which met in the center
to complete the structure.
โข In order to compensate for the
absence of balance cantilever,
abutments are made extra heavy.
12. METHOD OF CONSTRUCTION
โข Cast-in-Situ Method
โข Suitable for Short bridges
โข Time consuming
โข Types-
โข Incremental launching method
โข Balanced cantilever method
โข Cast-in-Situ Post tensioned method
13. METHOD OF CONSTRUCTION
โข Cast-in-Situ Method
๏ Steps
โข Construction of lower infrastructure of the bridge i.e. abutment, piers, etc
โข Erection of ground supported staging
โข Casting the segments
โข Dismantling of staging
14. METHOD OF CONSTRUCTION
โข Precast Segmental Method
โข Suitable for Long bridges
โข Economical for multiple nos. of span
๏ Steps
โข Casting of Precast Segments in casting yard
โข Transporting the precast segments at the site
โข Erection of Precast segments using launcher or crane
โข External Pre-stressing
โข Grouting
15. ADVANTAGES OF CANTILEVER BRIDGE
โข False-work is not required
โข Suitable for longer span
โข Support is required only on one side of its cantilever.
โข As due to the absence or less noโs of piers in between the abutments, a wide
passage gets available.
16. DISADVANTAGES OF CANTILEVER BRIDGE
โข Cantilever bridges have to take care of its stability by balancing between
compressive as well as tensile forces acting on it.
โข Cantilever bridges are heavy, so it required larger and stronger support.
โข Not suitable for Earthquake Prone Area
โข Construction and the Maintenance of the Cantilever bridges are complex.
17. CASE STUDY
โข Wilson Creek Bridge- Southwest Virginia, US
Construction Phase
After Completion
18. CASE STUDY
โข Wilson Creek Bridge- Southwest Virginia
Side - Elevation of Wilson Creek Bridge
โข Total length- 605m (Divided in Five spans) and Width- 12m
โข Three center spans-144m & two side spans of 86.5m each.
Abutment B
Pier 1 Pier 2 Pier 3 Pier 4
Abutment A
86.50 m
144.00 m
144.00 m
Wilson
Creek
Wilson Creek Bridge
86.50 m 144.00 m
Ellet Road
19. BRIDGE & ITS FEATURES
โข Wilson Creek Bridge- Southwest Virginia, US
โข Location- It is in Montgomery County which is located in Salem District,
which comprises twelve counties in the southwestern part of Virginia.
โข The bridge will be crossing Wilson Creek and Ellet Road (Route 723) in Ellet
Valley.
โข Itโs a cast-in-place Segmental Balanced Cantilever bridge.
โข The bridge superstructure consists of a single box girder with cantilevering
flanges. It has a varying depth that reaches its maximum at the piers.
โข Piers are hollow cast-in-place shafts with a vertical taper.
โข Both abutments rest on footings that are 4.05 m long, 12.00 m wide, and on
average 1.30 m deep.
20. PARTIES INVOLVED
โข Owner- Commonwealth of Virginia Department of Transportation (VDOT).
โข Design for bidding purposes- Figg Engineers, Inc. of Tallahassee, FL.
โข Preparation of Drawings- Janssen & Spaans Engg, Inc. of Indianapolis, IN
โข Consultant- PCL Civil Constructors, Inc. of Coral Springs, FL (PCL).
21. CONSTRUCTION SEQUENCE
โข Site preparation- Cleared the trees and shrubs and completed grubbing.
โข Foundation Construction, Drainage & Earthwork
I. Excavation- Drilling & Blasting
II. Foundation
III. Earthwork filling up to 1 m
โข Substructure Construction- By traditional method
I. Abutments
II. Pier shafts
22. ERECTION SEQUENCE
โข Actual order- From higher level to lower level
Pier 2 - Pier 3 - Pier 4 - Pier 1
Dimensions Pier 1 Pier 2 Pier 3 Pier 4
Height (from footing top to girder
bottom)
24.524 m 41.314 m 38.514 m 25.943 m
Top width 6.000 m
Top depth 3.750 m
Bottom width 6.982 m 7.654 m 7.542 m 7.040 m
Bottom depth 4.978 m 5.818 m 5.678 m 5.050 m
23. ERECTION SEQUENCE
Construction Phase 1
Erection of segments by means
of Form Traveler on BHS of
Pier 2
Construction Phase 2
Erection of segments by means
of Form Traveler on BHS of
Pier 3
24. ERECTION SEQUENCE
Construction Phase 3
Erection of segments by means
of Form Traveler on BHS of
Pier 4
Construction Phase 4
Erection of segments by means
of Form Traveler on BHS of
Pier 1
25. FORM TRAVELER
โข Modern Technique for Bridge Construction.
โข It is a formwork that builds a bridge by moving on the bridge itself.
โข Long span bridges like cable stay and Long cantilever Bridges are
constructed most efficiently by balanced cantilever method by using FORM
TRAVELLERS.