The dampers are being provided at Cable Stayed Bridge site to reduce the effect of fatigue on the stay cables due to oscillations induced by wind or other external phenomena, stay cables of more than 80m lengths have been provided with Internal Radial Dampers (IRD).15 such dampers are being installed on the stays.

1. FREYSSINET INTERNATIONAL & Cie – TECHNICAL DEPARTMENT
1 bis rue du Petit Clamart – B.P. 135
78148 VELIZY-VILLACOUBLAY
Tel. : 33 1 46 01 85 10 – Fax : 33 1 46 01 86 52
PROJET, LOT, TITRE, TYPE DE DOC. / PROJECT, SCOPE, TITLE, DOC. TYPE__
BARDDHAMAN
Stay Cables
Damper
Working Procedure
PAYS / COUNTRY MOA / CLIENT MOE / CONTRACTOR
India
FREYSSINET INTERNAL REVISION STATUS_
E
D
C
B
A 03/01/14 ADN MBS IZC FIRST ISSUE
REV. DATE
RÉDIGÉ PAR
/ WRITTEN BY
VÉRIFIÉ PAR
/ CHECKED BY
APPROUVÉ PAR
/ APPROVED BY
MODIFICATION
FREYSSINET DOCUMENT N° REVISION
M13-014E1–PRA 006 A
Quality Management System certified by BUREAU VERITAS Certification
PAGE / SHEET
1 / 9
This document is the exclusive property of FREYSSINET. It is confidential and may not be used, reproduced or communicated either in whole or in part, in any
form or manner without the prior written agreement of FREYSSINET. This document shall not be distributed to third parties except under the terms of the contract.

2. BARDDHAMAN – Stay Cables
Damper – Working Procedure
M13-014E1–PRA 006 – Rev. A Quality Management System certified by BUREAU VERITAS Certification Page 2/9
This document is the exclusive property of FREYSSINET. It is confidential and may not be used, reproduced or communicated either in whole or in part, in any
form or manner without the prior written agreement of FREYSSINET. This document shall not be distributed to third parties except under the terms of the contract.
REV.
CONTENTS
1. SCOPE OF WORKS ........................................................................................3
2. ABREVIATIONS ..............................................................................................3
3. INTERNAL RADIAL DAMPER ........................................................................3
3.1 General description...................................................................................3
3.2 Ressources...............................................................................................4
3.3 Installation of the IRD................................................................................4
3.4 Crucial points............................................................................................7
3.5 ITP ............................................................................................................8

3. BARDDHAMAN – Stay Cables
Damper – Working Procedure
M13-014E1–PRA 006 – Rev. A Quality Management System certified by BUREAU VERITAS Certification Page 3/9
This document is the exclusive property of FREYSSINET. It is confidential and may not be used, reproduced or communicated either in whole or in part, in any
form or manner without the prior written agreement of FREYSSINET. This document shall not be distributed to third parties except under the terms of the contract.
REV.
1. SCOPE OF WORKS
The purpose of this document is to describe the different operations to be carried out for
the installation of the Internal Radial Dampers (IRD) for Barddhaman Bridge.
IRD are installed on cables whose length is above 80m. Therefore, IRD shall be installed
on the following cables:
- 7001 to 7004 on the main span of the central plane,
- 7018 on the back span of the central plane,
- 6001 to 6004 and 5001 to 5004 on the main span of the side plane,
- 6018 and 5018 on the back span of the side plane.
2. ABREVIATIONS
IRD Internal Radial Damper
AVT Anti-Vandalism Tube
GT Guide Tube
ITP Inspection and Test Plan
3. INTERNAL RADIAL DAMPER
3.1 General description
The IRD (Internal Radial Damper) are fabricated in factory. They are made of 4 main
components:
- the compacting collar that comes around the strand bundle and transfers the load
to the pistons,
- the three hydraulic pistons ensuring the damping,
- the three caps connecting the pistons to the guide tube,
- the guide tube attached to the deck.
Guide tubeThree Hydraulic Pistons
Cap
Compacting Collar

4. BARDDHAMAN – Stay Cables
Damper – Working Procedure
M13-014E1–PRA 006 – Rev. A Quality Management System certified by BUREAU VERITAS Certification Page 4/9
This document is the exclusive property of FREYSSINET. It is confidential and may not be used, reproduced or communicated either in whole or in part, in any
form or manner without the prior written agreement of FREYSSINET. This document shall not be distributed to third parties except under the terms of the contract.
REV.
3.2 Ressources
Workforce
1 Chief operator
2 Labourers
Plant and equipment
Crane or lifting device.
3.3 Installation of the IRD
The main stages of the IRD installation are the following:
- Preliminary works,
- Compacting collar installation,
- Guide tube centering,
- Preparation and installation of the hydraulic pistons
- Finishing works.
3.3.1 Preliminary works
Before installing the damper, the following operations shall be done:
- Lifting of the GT and securing it with safety bars,
- Marking of the collar position onto the strand bundle (refer to ITP for the correct
distance),
- Compacting of the strand bundle with straps,
- Installation of dummy strands (if the strand bundle is not fully completed).
Figure 1: Lifting the guide tube Figure 2: Marking the position of the damper

5. BARDDHAMAN – Stay Cables
Damper – Working Procedure
M13-014E1–PRA 006 – Rev. A Quality Management System certified by BUREAU VERITAS Certification Page 5/9
This document is the exclusive property of FREYSSINET. It is confidential and may not be used, reproduced or communicated either in whole or in part, in any
form or manner without the prior written agreement of FREYSSINET. This document shall not be distributed to third parties except under the terms of the contract.
REV.
3.3.2 Compacting collar installation
For the collar installation, the following operations shall be performed:
- Installation of the 2 half shells of the compacting collar between the 2 marks,
- Checking of the dummy strand position,
- Closing of the gap between the 2 half shells,
- Partial tightening of 2 bolts M16 to well place the collar in front of each other.
- Final tightening of the 6 bolts M16 (refer to ITP for the required torque).
- Installation of the 6 collar damper connectors with the 12 screws M12,
- Full screwing of the 6 adjusting pistons and nuts onto the 6 threaded rods of the
collar and installation of the 6 adjusting caps.
Figure 3: Compacting collar installed around the bundle
3.3.3 Guide Tube Centering
In order to allow the same stroke of the pistons in every direction, the guide tube shall be
centred around the strand bundle. The steps to do so are the following:
- Removal of the safety bars and lowering of the guide tube.
- Lifting of the AVT.
- Centering the guide tube around the strand bundle thanks to the oblong holes,
- Partial tightening of the 8 bolts M20 of the flange with the special washers,
- Settling of the 6 adjusting pistons at 40mm from the guide tube internal diameter,
- Lowering of the AVT with a crane.
Figure 4: lifting of the AVT Figure 5: GT centring
Compacting
collar
Collar
damper
connector Adjusting
pistons, nuts
and caps

6. BARDDHAMAN – Stay Cables
Damper – Working Procedure
M13-014E1–PRA 006 – Rev. A Quality Management System certified by BUREAU VERITAS Certification Page 6/9
This document is the exclusive property of FREYSSINET. It is confidential and may not be used, reproduced or communicated either in whole or in part, in any
form or manner without the prior written agreement of FREYSSINET. This document shall not be distributed to third parties except under the terms of the contract.
REV.
3.3.4 Preparation and installation of the hydraulic pistons
Hydraulic pistons shall be prepared in advance:
- Threading of the cap axle through the external end of the hydraulic piston, spacers
and cap connector,
- Threading of the collar axle through the internal end of the piston,
- Marking of the hydraulic piston at mid stroke and fully compressed.
Once all pistons are prepared, they can be installed on the compacting collar according to
the following operations:
- Placing of the collar axle into the collar connector grooves,
- Tightening of the 4 collar connector screws M12,
- Settling of the piston to mid stroke,
- Installation of the cap and fixation to the cap connector,
- Fixation of the cap to the guide tube.
Figure 6: Cap Installation
3.3.5 Finishing Works
To finish the installation of IRD, the following operations shall be performed:
- Lowering the AVT,
- Fully tightening the 8 M20 bolts without modifying the GT orientation (the required
torque is indicated in the ITP),
- Application of sealant for waterproofness of the flange.

7. BARDDHAMAN – Stay Cables
Damper – Working Procedure
M13-014E1–PRA 006 – Rev. A Quality Management System certified by BUREAU VERITAS Certification Page 7/9
This document is the exclusive property of FREYSSINET. It is confidential and may not be used, reproduced or communicated either in whole or in part, in any
form or manner without the prior written agreement of FREYSSINET. This document shall not be distributed to third parties except under the terms of the contract.
REV.
3.4 Crucial points
• ITP: Refer to relevant ITP for installation data records (see §3.5).
• Hydraulic piston orientation:
o Top/bottom orientation
The hydraulic piston can be delivered with or without cap.
The top end shall always be higher than the bottom end.
WITHOUT CAP
o Angular orientation
The longitudinal orientation shall be controlled: the piston body shall be rotated
such that the marking at the lower end of the piston is oriented down.
Note : All the damper pistons shall be delivered with the indication “DOWN” that
shall be oriented down.
DOWN
indication
Gravity
Bottom end
Top end
Up
Down
Down
Gravity
Up

8. BARDDHAMAN – Stay Cables
Damper – Working Procedure
M13-014E1–PRA 006 – Rev. A Quality Management System certified by BUREAU VERITAS Certification Page 8/9
This document is the exclusive property of FREYSSINET. It is confidential and may not be used, reproduced or communicated either in whole or in part, in any
form or manner without the prior written agreement of FREYSSINET. This document shall not be distributed to third parties except under the terms of the contract.
REV.
3.5 ITP

9. BARDDHAMAN – Stay Cables
Damper – Working Procedure
M13-014E1–PRA 006 – Rev. A Quality Management System certified by BUREAU VERITAS Certification Page 9/9
This document is the exclusive property of FREYSSINET. It is confidential and may not be used, reproduced or communicated either in whole or in part, in any
form or manner without the prior written agreement of FREYSSINET. This document shall not be distributed to third parties except under the terms of the contract.
REV.