Usage of elastomeric pad as bearing in flyover make it as more flexible and creates isolation during earthquake

1. ANALYSIS AND DESIGN OF FLYOVER
ELEMENTS WITH ELASTOMERS
Presented by, Guided by,
1. R.V.Subbulakshmi S. Alarmelumangai, M.E
2. E.Yasodai Assistant Professor
3. S.P.Bavithra Department of CE
4. A.Parkavi A.V.C College of Engineering

2. OBJECTIVE
• To develop the simple method of seismic resistant in flyover
• To analyze and design the flyover elements.

3. ABSTRACT
• The aim of this investigation is provision of rubber bearing
isolators in flyover to withstand earthquake induced stress as
economically as possible.
• Flyover is high level road bridge.
• There is a necessity to construct a road over bridge in ongoing
bypass project connecting Vallam to Thiruvaiyar, since the bypass
alignment crosses railway line in between Alakudi and Tanjore.

4. FLYOVER
• A grade separated structure connects road at different levels for
the purpose of reducing vehicle congestion.
• To make road easily accessible for day to day traffic.

5. FLYOVER ELEMENTS
SUPER-STRUCTURE:
1. Deck slab, Approach slab,
2. Girder, Bearing,
3. Parapet wall and Hand rail.
SUB-STRUCTURE:
1. Abutment, Pier, Wing-wall.
2. Foundation.

6. NECESSITY OF PROJECT
• At railway crossing there is a high traffic congestion in terms of
train passing by or traffic on the road.
• In such a case flyover is indispensable.
• Furthermore earthquake causes failure of structures leads to several
loss. Structure has to withstand the earthquake force.
• So in our project we designed flyover elements with earthquake
resistant technique.

7. BASE ISOLATION SYSTEM
• It is one of the most popular earthquake resistant technique which
isolates substructure and super structure during earthquake.
• Here elastomeric bearing is used. It is ductility incorporated
technology which consist of a layer of neoprene bonded to steel
laminates.

8. CONTD..,
• Elastomers is placed between deck slab and pier.

9. LITERATURE REVIEW
• ANALYSIS OF T BEAM BRIDGE DECK USING FINITE
ELEMENT METHOD: T Beam Bridge decks are one of the
principle types of cast-in place concrete decks. It is suitable when
span is 10-25m. A simple span T beam bridge was analyzed by using
IRC CLASS AA loadings as a one dimensional structure. Girder is
analyzed as per Courbon’s method. IRC class AA loading consist of
either tracked vehicle of 70 tons or wheeled vehicle of 40 tons.
Courbon’s method is suitable for deck having span to width ratio
greater than 2 but less than 4.

10. EARTHQUAKE- A CASE STUDY
• A devastating 7.8 R earthquake struck northern Nepal on April 25,
2015 injuring over 22,000 people in addition to causing
significant infrastructure damage.
• Bhuj earthquake of magnitude 7.7 R occurred on January 26,
2001 had devastated many human lives nearly 18,000 peoples are
died
• So it is necessary to control seismic potential on structure in
order to access a protection towards human race and structures.

11. ALSO WE LOSS OUR PRIDE IDENTITY
(NEPAL)

12. METHODOLOGY
Site Selection
Data collection
Traffic Survey
Analysis
Design of Structural
Components

13. SITE SELECTED
• We are proposing our flyover project in lieu of existing railway
level crossing at Alakudi near Tanjore in Vallam to Thiruvaiyaru
Bypass (on going).

14. SITE DETAILS
1. Type of road: State highway(SH 100)
2. Name of the road: Tanjore-Vallam road
3. Distance between level crossing (boom to boom): 30m
4. Type of rail gauge: Broad gauge
5. TVU (train vehicle unit): 55 units/ day
6. Seismic zone: II

15. Prop. Bye Pass
Total Length : 14.265 Km
Lane Configuration
Km 0/0 - 1/6 Four Lane,
Km 1/6 – 14/265 Two Lane
Proposed ROB CH 5706
PROPOSED LOCATION

16. TRAFFIC SURVEY DETAILS
• MANUAL METHOD OF COUNTING

17. TRAFFIC DENSITY
VEHICLE TYPE TRAFFIC DENSITY
(veh/km)
Two wheeler 523
Auto 258
Buses 44
Car 50
Truck 22
Other vehicles (tractor,
cycle )
68 (app)
Location: Tanjore (Time: 9.30-10.30 A.M)

18. ANALYSIS
• IRC CLASS AA LOADING is considered for design of flyover
elements. It consist of either tracked vehicle (700 kN) or wheeled
vehicle (400 kN).
• Example: combat tank used by army.

19. DESIGN OF STRUCTURAL ELEMENTS
Type of bridge deck : T-Beam cum slab
Loading : IRC 6 (Class AA loading considered)
Bridge deck : Working stress method
Bearing : IRC 83-part II(WSM)
Pier : IRC 78 & SP 16 Design Aids (LSM)
No of piers : 14
No of abutment : 2
Number of lane : 2
Overall width : 8m
Gradient : 1 in 30m
Length : 440m
1. Longitudinal girder
2. Cross girder
:
:
3 no’s
5 no’s

20. DESIGN OF DECK SLAB

21. CONTD…
Kerb 600x300mm
Wearing coat 80mm
Thick of deck slab 250mm
Area of reinforcement for
shorter span
16 mm ϕ bars at 150 mm c/c
Area of reinforcement for
longer span
10 mm ϕ bars at 150 mm c/c

23. DESIGN OF LONGITUDINAL GIRDER
• Analysis is done using COURBON’S THEORY
Width of main girder =300mm
Depth of main girder =1600mm
Area of reinforcement 20 no’s of 32 mm ϕ rods in 4
rows
Stirrups 10 mm ϕ bars – four legged
stirrups at 200 mm c/c

24. DESIGN OF CROSS GIRDER
• Analysis is done using COURBON’S THEORY
Width of cross girder =300mm
Depth of cross girder =1600mm
Area of reinforcement 4 no’s of 20 mm ϕ rods
Stirrups 10 mm ϕ bars – four legged
stirrups at 150 mm c/c

26. DESIGN OF ELASTOMERIC BEARING
• This design conforms IRC 83 PART-II.
• Provide 3nos of 400 X 250 X 50 mm laminated elastomeric bearing
between concrete pedestals of 650 X 450 X 120 mm.
• It offers flexibility between pier and deck slab during earthquake
as per shown.

28. DESIGN OF SUB-STRUCTURE
• DESIGN OF PIER CAP: This conforms IRC 78-2000.
Length of pier cap 10.6 m
Width of pier cap 1.2 m
Effective depth(d1) 1.8 m
Tension reinforcement 20 no’s of 32 mm ϕ rods
Compression reinforcement 36 no’s of 32 mm ϕ rods
Side-face reinforcement 8 no’s of 20 mm ϕ rods in 2
rows
Shear reinforcement 22 mm ϕ rods – four legged
stirrups at 500mm c/c

29. DESIGN OF PIER
Length of pier 5.6 m
Width of pier 1.2 m
Height of pier 5.2 m
Tension reinforcement 68 no’s of 32 mm ϕ rods
Curtailment 34 no’s of 32 mm ϕ rods
Shear reinforcement 12 mm ϕ rods – four legged
stirrups at 250mm c/c

32. CONCLUSION
• Road traffic jams continue to remain a major problem in most cities around
the world especially in developing regions resulting in massive delays,
increased fuel wastage and monetary losses. Hence grade separated
structures offers a free flow of traffic.
• In this project we designed a road over bridge elements in order to avoid
traffic congestion in our proposed project site. Furthermore earthquake
causes major disasters and leads to failure of structures.
• So in our project we are introducing an elastomeric base bearing in the
bridge which protect the structure during earthquake. All elements are
designed manually.

33. REFERENCE
• Ponnuswamy.S, “Bridge Engineering” publisher, Tata MeGraw-Hill, New
Delhi.
• Krishna Raju. N, “Advanced reinforced concrete design”, CBS publishers
and distributors Delhi, 2006.
• IS 456-2000 Indian standards - Plain and Reinforced concrete – code of
practice.
• IRC 6-2000 Specification for Road bridges-Section-2-Code of practice.