case study on signature bridge

1. RAJEEV INSTITUTE OF TECHNOLOGY
HASSAN
Department of Civil Engineering
TECHNICAL SEMINAR
on
“CASE STUDY ON SIGNATURE BRIDGE”
Under the guidance of
Mrs. RASHMI A S
Assistant Professor
Presented by:
TEJAS D A
4RA16CV107
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2. 2
CONTENTS
1. INTRODUCTION
2. COMPONENTS OF SIGNATURE BRIDGE
3. ASSESMENTS AND ERRECTION
4. CONCLUSION

3. 3
Introduction
Signature bridge:
• The Signature Bridge is a cantilever spar cable-stayed bridge. It
spans the Yamuna river at Wazirabad section, connecting Wazirabad
to East Delhi.
• It is India's first asymmetrical cable-stayed bridge.
• The pylon of the Signature bridge is the tallest structure in Delhi
and is double the height of Qutb Minar with its 154-metre high
viewing box, which acts as selfie points for visitors. It shortens the
travel time between north and northeast Delhi.
• This bridge is self-anchored bridge in which cables are anchored at
the deck level. Main advantage of this self-anchored bridge is that it
allow transmission of forces from backstays to deck with rendering
the deck self-equilibrated in the longitudinal direction.

4. 4
Signature bridge
Areal view of Signature bridge

5. Detail of the bridge
• Structural Design Firm: Schlaich Bergermann Partner
• Contractor: Joint Venture Gammon India[6][13] and Tensa India
Construtora Cidade
• Main span: 251 m
• Height of pylon: 165 m above ground
• Total length of infrastructure project: 6 km (approx.)
• Lanes: 2 x 4
• Deck surface: 25,000 m2
• Total length of bridge: 675 m (incl. 100 m west extension)
• Side spans: 36 m
• Structural steel pylon: 5800 tonne
• Structural steel deck: 7400 tonne
• Open foundation: 6 nos.
• Closed foundation: 16 nos.
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6. Components of signature bridge
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7. Detail of components
Foundation:
The final structure concluded for 23 foundation Out of which 16 wells of 8-9
m diameter sunk up to the level 500 mm above the highest rock level with
sixteen 1.20 m diameter piles inserted through the walls of the well embedded
up to 6m into rock on each wells, a combined tie beam of 4.5 m deep and 42 m
x 17.5 m sizes on top of the well connecting the wells, piles and piers
constructed on top of the same.
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8. Bearings:
There are 20 free spherical bearings, two large fixed bearings under
pylon legs of the capacity of 17,000t, two numbers of longitudinally
guided spherical bearings at the location of expansion joimts to
enable reversible momvement of 270mm and rock bearing under
backstay anchor foundation, which can tranfere the tensile faorce of
6,380t within main cable stay system. The two inclined pillars merge
at half height of the pylon. Above that point, the backstay cables and
the inclined cables lead into the pylon.

9. .
Deck:
Two carriage way, typically 14m wide and separated by a concrete crash barriers as
well as two lateral emergency pathways, from the deck of the bridge that total 35.2m in
width. Each of the carriage way accommodates four traffic lanes. The deck is formed of
outer I-shaped longitudinal main girders at 4.5m intervals. A third central nain girder is
placed to distribute heavy truck loads onto the several cross girders. All structural steel
is grade S355. Shop welding and site splices with high strength friction grip bolts will
be used. The deck is transversally supported on both ends of the bridge and at the
pylon. The only longitudinal movement of the deck at its western end is 250mm
approximately.

10. Cables:
The deck is supported by two cable planes. The cables are directly anchored to
the webs of the outer main girders at 13.5 meter distances with their dead end,
and are stressed with in the stressing chamber at the top of the pylon. The
cables will be made up of bundles of parallel 0.6'' strands grsde 1770.
depending on the location the number of strands per cable varies from 55 to
123 no. at the main span end is 127no. for each of the backstays. corrosion
protection will be international practice i.e., with hot dip galvanized wires and
individually coated strands that are covered by an PEpipe. In the backstay area
the lower part of the cables will be covered with steel tubes for fire protection.
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11. Fabrication
• Construction of the super structure involved fabrication and erection of about
14,500Mt of structural steel for permanent structure. The pylon with its harp shaped
body , leaning backwards, would be the most unstable structure during construction
stage.
• Pylon is complex structure having inclination in all directions. It is made up of
irregular pannels wleded out of varying steel plates of different grades. To
thoroughly understand the complexities of the structure , dimensional weights of
the elements to be fabricated, transported and erected, a true-to-scale digital model
of the bridge was prepared in Tekla.
• Some of the major challenges involved as using plat thickness ranging from 2.5 to
250mm including Z quality steel and drilling almost 8,50,000 holes for HSFG bolts
ranging from 12mm to 36mm in plates upto 120mm thick.
• To ensure fabrication accuracy many test were carried out like Dye penetration test,
ultrasonic test etc.
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12. • Two methods for drilling of holes were specially devised. Pre-drilled holes on web
plate of the connection during panel fabrication and post-drilling for other holes
which are marked and drilled with template after fit-up, welding, rectification and
milling of segments.
• All the compression joints were designed to transfer load through bearing contact
surface along with the splice connection.
• The pylon included three parts; steel segments, main body , pylon head segments.
• Steel leg was divided into 11 large segments, main body was divided into 5 large
segments, front cable pylon was divide into 5 large segments.
• The fabrication of pylon included base fabrication, leg fabrication, main body
fabrication band back body segments fabrication.
• Fabrication and erection of segments were divided into 3 parts: panelling
fabrication, shop assembly and trial assembly bon site into large blocks for erection,
erection and bolt connection on site.
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13. Erection
• The pylon is composed of two legs,box girders, inclined backwards and inward and
connected at a level of 63m by a main body that is vertical shaft with variable cross
section which hosts the top anchorages for the stay cables. The legs have
rectangular box girder with a constant width of 2.50m and height varying from 7.20
to 9.60m.
• The pylon was divided into segment with weights varying from 40t to 250t. The
joints between the segments were flanged bolted joints with machined flnages.
• After working out several alternative, it was proposed to erect pylon using 1,250t
crawler crane, while the pylon would be supported with a specially designed
temporary struts until the system is stable after installation of permanent cables.
Segments weighting more than 40t to 250t were required to be erected.
• Pre-cast deck panels were erected over girders using the Goliath gantry for deck
erection towards the river side .
• For correct positioning, with double inclination, of pylon segments was achieved by
a specially designed turn table.
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14. • Structural geometry was checked at installation of every element and daily survey
procedure started at the beginning of stay caboe stressing.
• While monitoring the effect of construction lodings, element loadings and cable
stressing on deformation of pylon and decks, the following correction factors of the
environmental effects had to be applied. The pylon position changed rapidly during
the day, with movements around 20mm in the longitudinal and vertical direction
and upto 40mm in transverse direction.
• Stay cable consists of 19 pairs of cables with varying number of stands minimum
being 55 to maximun 127 of 15.70 mm dia with GUTS of 1,770Mpa.
• Stay cable strands preparation consists of pulling out the strand from coil drum,
laying on the bench , uncoating, cutting and marking for identification.
• Strands in the cables were tensioned using iso-elongation method. This method
utilise Moni strand jack attached with a load cell, hydraulic pump, dynamometer for
calibration of pump-jack system.
• A topographic survey of the bridge during each stressing phase was provided. After
reaching 80% of the stressing force in each phase, new elongation to be applied to
the strand had to be provided considering the actual load registered and the data
collected from the topographic survey.
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15. Inference
It symbolises the standard for iconism in India.
3-dimensionally varying pylons being attempted
first time and over comes many other complex
issues by proper construction engineering.
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