Cantilever bridge construction

The presentation is about cantilever bridge construction and its techniques and a case study in the end.

1. Cantilever Bridge Construction prepared by Kundan Sahadev Sanap Seat No. 202030016 VJTI, Matunga

2. Table of Content Introduction about Bridge Types of Bridges Cantilever Bridge History of Cantilever Bridge Types of Cantilever Bridge Method of Bridge Construction Advantages of Cantilever Bridge Disadvantages of Cantilever Bridge Case study- Wilson Creek Bridge, South west Virginia Form Traveller System

3. Introduction 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 . 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.

4. Types of bridges Arch Bridge Beam Bridge Cable stayed Bridge Truss Bridge Suspension Bridge Cantilever Bridge

5. Cantilever Bridge A bridge built using cantilever structures that projects horizontally into space, supported on only one end. There are some special conditions where the number of supports cannot be given, in that case,  Cantilever Bridges  are suitable For small footbridges, the cantilevers may be simple beams; however large cantilevers bridges are designed using trusses. 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.) 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. 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 First cantilever bridge appeared in 19th century when there was a need for longer bridges. 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 . The one to be the first to invent and patent a cantilever bridge was Heinrich Gerber which did it in 1866 . Hassfurt Bridge over the Main River in Germany .

8. Types of Cantilever Bridges On the basis of method of construction Balanced Cantilever Bridges Continuous Cantilever Bridges

9. Types of Cantilever Bridges (Contd.) Balanced Cantilever Bridges most efficient methods of building bridges It does not require false work for construction. This method has great advantages as compared to other forms of construction in urban areas, where temporary  shoring  will disrupt traffic and services 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.) Balanced Cantilever Bridges Construction begins at the permanent piers and proceeds mid-term in a balanced manner as shown in fig. The structure is hence self-supporting at all stages. The construction may either be cast-in-situ or can be precast.

11. Types of Cantilever Bridges (Contd.) Continuous Cantilever Bridges The bridge was constructed using two gantries from the opposite end (abutments) which met in the center to complete the structure. In order to compensate for the absence of balance cantilever, abutments are made extra heavy .

12. Method of construction Cast-in-Situ Method Suitable for Short bridges Time consuming Types- Incremental launching method Balanced cantilever method Cast-in-Situ Post tensioned method

13. Method of construction Cast-in-Situ Method Steps Construction of lower infrastructure of the bridge i.e. abutment, piers, etc Erection of ground supported staging Casting the segments Dismantling of staging

14. Method of construction Precast Segmental Method Suitable for Long bridges Economical for multiple nos . of span Steps Casting of Precast Segments in casting yard Transporting the precast segments at the site Erection of Precast segments using launcher or crane External Pre-stressing Grouting

15. Advantages of cantilever bridge False-work is not required Suitable for longer span Support  is required only   on one side of its cantilever . As due to the absence or less no’s of piers in between the abutments, a wide passage gets available.

16. Disadvantages of cantilever bridge Cantilever bridges have to take care of its stability by balancing between compressive as well as tensile forces acting on it. Cantilever bridges are heavy, so it required larger and stronger support. Not suitable for Earthquake Prone Area Construction and the Maintenance of the Cantilever bridges are complex.

17. Case study Wilson Creek Bridge- Southwest Virginia, US Construction Phase After Completion

18. Case study Wilson Creek Bridge- Southwest Virginia Side - Elevation of Wilson Creek Bridge Total length- 605m (Divided in Five spans) and Width- 12m 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 Wilson Creek Bridge- Southwest Virginia, US Location- I t is in Montgomery County which is located in Salem District, which comprises twelve counties in the southwestern part of Virginia . The bridge will be crossing Wilson Creek and Ellet Road (Route 723) in Ellet Valley. It’s a cast-in-place Segmental Balanced Cantilever bridge. The bridge superstructure consists of a single box girder with cantilevering flanges. It has a varying depth that reaches its maximum at the piers . Piers are hollow cast-in-place shafts with a vertical taper . 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 Owner- Commonwealth of Virginia Department of Transportation (VDOT). Design for bidding purposes- Figg Engineers, Inc. of Tallahassee, FL. Preparation of Drawings- Janssen & Spaans Engg, Inc. of Indianapolis, IN Consultant- PCL Civil Constructors, Inc. of Coral Springs, FL (PCL).

21. Construction Sequence Site preparation- Cleared the trees and shrubs and completed grubbing. Foundation Construction, Drainage & Earthwork Excavation- Drilling & Blasting Foundation Earthwork filling up to 1 m Substructure Construction- By traditional method Abutments Pier shafts

22. Erection Sequence A ctual 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 Modern Technique for Bridge Construction. It is a formwork that builds a bridge by moving on the bridge itself. Long span bridges like cable stay and Long cantilever Bridges are constructed most efficiently by balanced cantilever method by using FORM TRAVELLERS.

26. The End !!!