ANALYSIS AND DESIGN OF FLYOVER ELEMENTS WITH ELASTOMERS

Presented by, Guided by,1. R.V.Subbulakshmi S. Alarmelumangai, M.E2. E.Yasodai Assistant Professor 3. S.P.Bavithra Department of CE4. A.Parkavi A.V.C College of Engineering

OBJECTIVE

• To develop the simple method of seismic resistant in flyover

• To analyze and design the flyover elements.

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.

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.

FLYOVER ELEMENTS

SUPER-STRUCTURE:

1. Deck slab, Approach slab,

2. Girder, Bearing,

3. Parapet wall and Hand rail.SUB-STRUCTURE:

4. Abutment, Pier, Wing-wall.

5. Foundation.

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.

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.

CONTD..,

• Elastomers is placed between deck slab and pier.

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.

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.

ALSO WE LOSS OUR PRIDE IDENTITY (NEPAL)

METHODOLOGY

Site Selection

Data collection

Traffic Survey

Analysis

Design of Structural Components

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).

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

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

TRAFFIC SURVEY DETAILS

• MANUAL METHOD OF COUNTING

TRAFFIC DENSITY

VEHICLE TYPE TRAFFIC DENSITY (veh/km)

Two wheeler 523Auto 258Buses 44Car 50Truck 22Other vehicles (tractor, cycle )

68 (app)

Location: Tanjore (Time: 9.30-10.30 A.M)

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.

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

DESIGN OF DECK SLAB

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

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

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

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.

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

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

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.

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.

Thank You