girder launching

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1 PROJECT REPORT ON LAUNCHING OF PSC GIRDER ACROSS ENNORE CREEK BRIDGE by (NOSE LAUNCHING METHOD) By- K. RAJENDRAN ADEN/SR A.B. NANDAGAWALI ADEN/CR A.B. KANDALGAONKAR AXEN/CR Course No. 9101 Acknowledgement We are grateful to - Sri N. LALWANI, Sr. Professor who has guided us right through the study of this project. We are also thankful to - Sri ARUN CHANDOLIKAR, Course Director for having helped us in this training programme.

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Deals with launching of precast prestressed girder.

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Page 1: Girder Launching

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PROJECT REPORTON

LAUNCHING OF PSC GIRDER ACROSS ENNORE CREEK BRIDGE

by(NOSE LAUNCHING METHOD)

By-K. RAJENDRAN ADEN/SRA.B. NANDAGAWALI ADEN/CRA.B. KANDALGAONKAR AXEN/CR

Course No. 9101

AcknowledgementWe are grateful to -

Sri N. LALWANI, Sr. Professor who has guided us right through the study of this project.

We are also thankful to -

Sri ARUN CHANDOLIKAR, Course Director

for having helped us in this training programme.

Page 2: Girder Launching

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SYNOPSIS:

• The Chennai Central – Gudur section is the `A’ Group Route identified for CC+8 loading. This route crosses the Bay of Bengal between Ennore-Attipattustations There is a bridge of 30 Nos of 12.2 M. span of steel Girder. This bridge also serves for the navigational purposes as such the depth of construction was restricted.

• The bridge was constructed during the year 1899 and served more than its codal life. This is one of the major bridge in MAS-GDR section The above bridge is stone masonry jacketed with cement concrete. Since, the sub structure is always in back water of Bay of Bengal, the sub structure is weathered due to low and high tide of sea. The superstructure is very badly corroded and knife edged. Hence, this bridge was proposed to rebuild in view of safety. Reconstruction of this bridge was sanctioned and included in the Green book No.283 of 2004.(SRSF) The cost of this bridge works out to 10.38 crores.

• The new bridge is constructed at 10 m. apart of Up line bridge between the Up and Down Line.

Page 3: Girder Launching

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FOUNDATION:

•The new Bridge has 17 spans out of which 13 x 24.43 m and 4 x 10.715 M. Each pier has been constructed over a group of four 1000 mm dia. Cast-in-situ bored piles. Total of 76 piles had been completed within a period of 6 Months.

– DETAILS OF PILES:• a) Type : Bored cast in situ

piles.• b) Casing (Per manent) : 6mm thick M.S liner.• c) M ethod of pile operation : Bailer & chisel method.• d) Spacing of piles : 3 and 4 metres .• e) Cement content : 450 kg/cum.• f) Slump : 150mm• g) Depth of pile : 32 to 36M.• h) Reinforcement :• Fe.415. Main 25 Nos. of 32mm dia

Binder – 16mmdia @ 1500 C/C

• Rings – 10 mm dia @ 300 C/C

• i) Cover for reinforcement : 75mm• j) Method of concreting : Tremie pipe method.• RMC concrete.• k) Environmental condition : Very severe

Page 4: Girder Launching

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ANTI CORROSIVE TREATMENT

• Since the bridge is in very severe environmental conditions, all the reinforcement including PSC reinforcement were done with fusion bonded Epoxy as per IS:13620 of 1993 Thickness of coating – 250microns.

• All the tests in respect of quality of the above anticorrosive treatment were done at IIT Mumbai.

Page 5: Girder Launching

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SUB-STRUCTURE:

• The substructure consists of two Nos of 1200 mm dia. RCC columns and trestle beam over 1.5 m. depth of pile cap. (4.5m x 5.5 m. size)

Page 6: Girder Launching

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SUPERSTRUCTURE:• First 4 spans of 10.715 m. were casted cast-in-situ over the respectiv e

spans. • Remaining 13 spans of 24.43 m. were casted at one end of approach. The

superstructure has been designed as single PSC Box Girder of 24.43 m. clear span. The superstructure work has been taken up and completed in 12 months.

DETAILS OF PSC GIRDERS:• a) Ty pe : Post tensioned Box

Girder.• b) Ov erall length : 27.43 m.• c) Clear span : 24.43 m.• d) Weight of girder : 234 Tons• e) Depth of Girder : 1650mm• f ) Qty of concrete : 90 m3• g) Qty. of 12.7mm/7 : 4.5 MT• ply strands• h) Qty. of TMT steel : 12 Tons.• i) No. of cables : 14 cables.• j) Max. pre stressing force : 275 Tons.

PRECAUTIONS TO BE TAKEN DURING CASTING:

• Casting was done in a single pour by Ready Mixed Concrete.

• All cable ducts should be fixed firmly as per the profile.

• In end block portion, spacing of rods may be adjusted to avoid congestion and to ensure good concrete without any honey comb.

• Adequate number of side shutter vibrators shall be used to avoid honey comb.

• Side and end shutters should be fabricated in such a way that the same can be released without affecting beam concrete.

Page 7: Girder Launching

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SELECTION OF LAUNCHING SCHEME.

• Nose launching method is used for launching the PSC box girders over the newly built sub-structure since water flows continuously throughout the year.

Page 8: Girder Launching

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EQUIPMENT AND MATERIALS USED FOR LAUNCHING:

• Launching girder of 62 m. overall span of 32 Tons.• Lifting portals are made of ISMC 200 x 75, ISMB 450

x 150• Steel tank of size 2m x 2m x 1.5m. as counter weight

for launching nose.• Hydraulic power jacks – 8 numbers of 100 Ton

capacity.• 48 Nos. of 12.7 m dia / 7 ply HTS strands.• Special Wheel trolleys over which PSC girders are

transported.• Motorised winch – 20 HP capacity for pulling trolleys

with the PSC girders.• Two 52 kg rails had been fixed over the launching

girder to have a track of 1.67 m. gauge for the movement of trolleys.

Page 9: Girder Launching

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STAGES OF LAUNCHING WORK:

Lifting of PSC girder from casting bed and shifting it to the trolleys placed over the already laid track. A broad gauge track has been laid over the approach bank from the casting yard to the launching girder. Four jacks of 100 Ton capacity each had been used for lifting the PSC girder by 1800 mm from the casting bed so as to bring it to top level of trolleys. Then the girder placed over the trolleys by side slewing.

MOVING THE PSC GIRDER OVER THE TRACK UP TO THE SPAN WHERE LIFTING PORTALS ARE

AVAILABLE.A winch operated by 20 HP motor with reduction gear box is used for pulling the trolleys with the PSC girder. The girder is pulled at a speed 0.5m/min.

Page 10: Girder Launching

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