4. BRIDGES & BEARINGS
History
The first bridge bearings
to be used were plane bearings in the early 1800s,
which included sliding bearings or roller bearings.
Plane bearings allowed horizontal movement in one direction, and could therefore transfer horizontal load.
Rotating bearings were used in the late 1800s and early 1900s and included rocker bearings, knuckle bearings, and
ball bearings.
Rotating bearings allowed movement in both the horizontal and vertical directions.
Both plane bearings and roller bearings were made of metal.
In the mid-1900s, deformation bearings began to be used, which were made of rubber.
Deformation bearings primarily include elastomeric bearings,
the most common type of bridge bearing used today.
6. BRIDGES & BEARINGS
BRIDGE BEARINGS
INTRODUCTION
BRIDGE DECKS SUPPORTED BY PIERS ARE SUSCEPTIBLE TO DAMAGE DUE
TO VEHICLE MOVEMENT AND HEAT EXPANSION.
THE PRIMARY FUNCTION OF ELASTOMERIC BEARING PADS IS TO PROVIDE
A CONNECTION TO CONTROL THE INTERACTIONS OF LOADING AND
MOVEMENTS BETWEEN PARTS OF A STRUCTURE,USUALLY BETWEEN
SUPERSTRUCTURE AND SUBSTRUCTURE.
7. BRIDGES & BEARINGS
BEARING PADS ARE USED EXTENSITVELY IN BRIDGE STRUCTURE
PRE-STESSED AND PRE-CAST CONCRETE BUILDINGS.
ORF BEARINGS ARE MANUFACTURED FROM PREMIUM QUALITY
NEOPRENE/NATUTAL RUBBER.
ALL THE BEARING PADS ARE MANUFACTURED IN COMPLIANCE TO
STANDARS LIKE AASHTO, BS 5400,EN-1337,DIN 4141 ETC, HARDNESS
RAGING FROM 50 SHORE A TO 70 SHORE A .
UPON REQUEST,SPECIALLY DESIGNED BEARING PADS FOR NON-
STANDARD APPLICATION CAN ALSO BE PROVIDED. INCLUDING TESTING
AND APPLICATION.
8. BRIDGES & BEARINGS
•BEARING FUNCTION
• PERMIT LATERAL MOVEMENTS DUE TO TEMPARATURE CHANGE,TRAFFIC
MOVEMENTS,WIND,SHRIKAGE AND CREEP,FOUNDATION
MOVEMENTS,SEISMIC ACTIONS,DYNAMIC FORCES AND RESULTING
VIBRATIONS.
• TRANMITTING LOAD TO SUBSTRUCTURE FOUNDATIONS
• ACCOMMODATE GIRDER ROTATION
• SUPPORT VERTICAL LOADS
10. BRIDGES & BEARINGS
Bearings
A bridge bearing is a component of a bridge
transmitting the loads received from the deck on to the
substructure and to allow controlled movement due to temperature
variation or seismic activity and thereby reduce the stresses
involved.
A bearing is the boundary between the superstructure and the
substructure.
11. BRIDGES & BEARINGS
•A bridge bearing is a component of a bridge
which typically provides a resting surface between bridge piers and
the bridge deck.
• The purpose of a bearing is to allow controlled movement and thereby
reduce the stresses involved.
• Possible causes of movement are thermal expansion and contraction,
creep, shrinkage, or fatigue due to the properties of the material used for
the bearing.
• External sources of movement include the settlement of the ground
below, thermal expansion, and seismic activity.
• There are several different types of bridge bearings which are used
depending on a number of different factors including the bridge span,
loading conditions, and performance specifications.
12. BRIDGES & BEARINGS
The oldest form of bridge bearing is simply
two plates resting on top of each other.
A common form of modern bridge bearing is the elastomeric bridge
bearing.
Another type of bridge bearing is the mechanical bridge bearing.
There are several types of mechanical bridge bearing, such as the
pinned bearing, which in turn includes specific types such as the rocker
bearing, and the roller bearing.
Another type of mechanical bearing is the fixed bearing, which allows
rotation, but not other forms of movement.
13. BRIDGES & BEARINGS
A bearing is a negligibly small part of a bridge and
unfortunately the attention it receives from the engineers is also
negligibly small.
In fact, the importance of this small part should have been inversely
proportional to its size, as the entire load is transmitted through this
tiny component and any mis-behaviour of bearing may lead to
catastrofic results both for substructure as well as superstructure.
Therefore, selection, fabrication, installation and maintenance of
bearings should be on the top of list as far as the bridges are
concerned.
15. BRIDGES & BEARINGS
•ELASTOMERIC BEARINGS
• GENERAL Steel bearings are good but suffer from problems of corrosion
and high level of maintenance.
• Due to these problems of steel bearings, engineers were on the lookout
for a bearing which could accomodate large movements and at the same
time being relatively maintenance free.
• Elastomer as a material for making bridge bearing has been found to
satisfy these requirements so much so that many engineers believe that
the search for an ideal material for bridge bearing has come to an end.
• Further developments in future may involve refining the use of elastomer
and enhancing its properties.
17. BRIDGES & BEARINGS
Elastomeric Bearing Aging of
rubber is dependent on exposed
temperature.
Temperature of rubber bearings is affected by environmental conditions
such as ambient temperature, solar radiation, and wind. In addition to these
environmental conditions, a size of rubber bearing affects the bearing
temperature.
Aging of rubbers can be caused by oxygen, ozone, heat, light, dynamic
strain, oil and other liquids.
As a result of aging, rubber will stiffen and its tensile strength and
elongation at break Deterioration of will decrease.
19. BRIDGES & BEARINGS
Therefore, due to aging of rubber,
rubber Rubber Bearing bearings tend to increase their stiffness over time,
resulting in the increase in the fundamental frequency of the isolated structure
from its design value.
For vibration isolation the natural frequency of the supported structure should
be less than that of the disturbing frequency by a factor of at least 2 and
preferably 3.
Solar radiation is one of the most influential factors on the bearing temperature
and affects the temperature variation inside the rubber bearing.
Side surfaces of bearing receive the solar radiation.
A pyranometer is used for measuring solar radiation flux density (W/m²).
20. BRIDGES & BEARINGS
• To summarise, the elastomeric bearings offer number of advantage as
listed below:
• 1. Requires minimum maintenance compared to all other bearings.
• 2. Installation is easy.
• 3. Permits movement of the structure in all directions, depending upon the
applied forces.
• 4. Occupies small space.
• 5. Serves as a shock absorber due to anti-vibration properties of elastomer.
• 6. Acts as an aid to better dispersion of longitudinal forces to the
approaches.
21. BRIDGES & BEARINGS
The provision of IRS :
Bridge Rules in force on Indian Railways are explained below:
1. The quantum of longitudinal force is laid down in appropriate
EUDL tables in the appendix to the IRS : Bridge Rules.
2. Subject to proper standard and condition of track on bridge
approaches and provision of rail free fastening on the girders,
25% of the longitudinal force subjected to a minimum of 16t for BG,
can be considered to be dispersed on to the bridge approaches.
22. BRIDGES & BEARINGS
3. In case, suitably designed elastomeric bearings are used, the above
dispersion can be further increased by 40%.
Thus use of elastomeric bearings results in 35% of longitudinal force
being thrown on to the approaches.
4. In case of a span having free-fixed bearing combination, the full
longitudinal force (net after dispersion) is transmitted to the pier with
fixed bearing
5. In case of a span having sliding bearing or elastomeric bearings at
both ends the net longitudinal force is shared @ 40% at either support
point, the remaining being shared by the piers beyond the loaded span.
23. BRIDGES & BEARINGS
Though the above provisions are considered to be conservative by
many, it still shows a clear cut benefit of replacing steel sliding
bearings or rocker & roller bearings by elastomeric bearings.
A note of caution is however necessary that the amount of
dispersion will also depend upon the capacity of the rails, joints and
approach track to transmit and absorb the longitudinal force.
It is however beyond doubt that more studies are necessary in this
area and there is scope for retaining old substructures by use of
elastomeric bearings.
24. BRIDGES & BEARINGS
While replacing other bearings especially rocker
& roller by elastomeric, the correction slip no. 6
to Concrete Bridge Code dated 30.7.2002 should
be kept in mind,
which states that “use of elastomeric bearings in
prestressed concrete bridges should preferably be
restricted up to maximum clear span of 30 m.”
25. BRIDGES & BEARINGS
Types of bridge bearings
Rocker bearings
Rocker bearings have curved surfaces that allow rocking.
As the bridge expands, the bearing rocks to allow movement in the
horizontal direction.
Rocker bearings are primarily made of steel. Rocker bearings tend to
be used for highway bridges.
26. BRIDGES & BEARINGS
Elastomeric bearings
Elastomeric bridge bearings are the most popular type of bridge bearing
used today.
They are made of rubber and do not have any moving parts, because the
rubber itself allows movement in the bridge.
Elastomeric bearings can be made at a low cost, and do not need to be
maintained, like other forms of bearings that have moving parts and are
made of metal.
Elastomeric bearings can be reinforced with steel to make them stronger
if needed.
27. BRIDGES & BEARINGS
Sliding bearings
Sliding bearings have both a flat sliding surface to allow horizontal
movement and a spherical surface to allow rotation. Although they used
to be made of metal, sliding bearings now tend to be made of Teflon
Spherical bearings
As the name suggests, spherical bearings are in the shape of a sphere.
These bearings only allow rotation, and prevent movement in the
horizontal and vertical directions.
28. BRIDGES & BEARINGS
Functions of bridge bearings
They are one of the most important components of bridges.
They transfer forces from bridge superstructure to substructure.
Mainly two types of loads: Vertical Loads such as the structure's weight and
vehicle load, and Lateral Loads including earthquake and wind forces.
They permit movements like translation and rotation in between girders and
pier caps of bridges to accommodate movements such as thermal expansion.
Neoprene bearing pads (rubber like structure), a special type of bridge bearing,
loses its energy through deformation.
It simplifies the load transfer mechanism and hence, making analysis easier.
29. BRIDGES & BEARINGS
•References
• ^ Lee, David J. (1994).
• Bridge Bearings and Expansion Joints. Taylor & Francis Group. pp. 4–5. ISBN 0-419-14570-2.^ Gilstad Drew E. (1990-05-01).
• "Bridge Bearings and Stability".
• Journal of Structural Engineering. 116 (5): 1269–1277. doi:10.1061/(ASCE)0733-9445(1990)116:5(1269 Brinckerhoff, Parsons (1993). Silano,
Louis G. (ed.).
• Bridge Inspection and Rehabilitation: A Practical Guide. John Wiley & Sons. p. 183. ISBN 0471532622. Fu, Gongkang (2013).
• Bridge Design and Evaluation: LRFD and LRFR. John Wiley & Sons. p. 304. ISBN 1118332687.
• ^ Wetzk, Volker (2006).
• Bridge Bearings - A Historical Survey. ISBN 0-7017-0205-2Jc Fu, Gongkang (2013).
• Bridge Design & Evaluation LRFD and LRFR. John Wiley & Sons, Inc. pp. 303–312. ISBN 9781118332689.
• Stanton, J F, Roeder, CW (1982).
• "Elastomeric Design, Construction, and Materials". NCHRP Report: 248.
30. BRIDGES & BEARINGS
Common problems with Pot-cum-PTFE
bearings
The concept of pot bearing is based on effectively confining the elastomer within a metallic
piston-cylinder arrangement so that the elastomer remains in a state of uniform strain and no
tension is produced while subjected to very large compressive stress.
Unlike traditional laminated elastomeric bearing, such a perfectly confined elastomer, while
subjected to large compressive stress, behaves like a viscous fluid and therefore is capable to
cater for high degree of multi directional rotational movement.
Extremely tight tolerance of manufacturing is required to be maintained together with properly
detailed effective sealing system to confine the elastomer effectively.
If the steel piston is manufactured with high tolerance relative to the base pot, a condition of
steel-to-steel contact develops which inhibits the rotational capacity of the bearing device.
When the piston is manufactured with a low tolerance relative to the base pot, the sealing ring
has difficulty in containing the elastomer, which acts like a fluid under pressure.
31. BRIDGES & BEARINGS
2. There have been a number of problems with pot bearings,
due to inadequate design, incorrect selection of raw material and improper
production technique.
Leakage of the elastomer has been noted, even with bearings, considered well
manufactured.
Abrasion or wear of the elastomeric pad has also been noted in some cases.
A number of reasons have been postulated for these problems including
inadequate clearances or tolerances between the piston and cylinder,
excessive rotation, number of rotational cycles or lateral loads, abrasion of the
sealing ring, deformation of the Pot due to excess lateral load or gravity load,
inadequate surface finish of the portion of piston/cylinder in contact with
elastomer pad etc.
The other problems include inability of the steel pot to withstand the transverse
loadings, combined with the pressure developed from the elastomer.
32. BRIDGES & BEARINGS
the fact that satisfactory rotational distribution is not
achieved until a load of atleast 25% of the bearing capacity,
is applied.
The rotational resistance of the confined elastomer pad, though not negligible, is often ignored
due to lack of understanding of behavior of the pad and in some cases due to absence of data.
Another problem has been experienced with the pot concept in cold climates.
This deals with the rotational element being typically manufactured from synthetic rubber
(chloroprene rubber) as in India.
During extreme cold temperatures, coupled with high-design pressures, the rotational element
has been known to crystallize, which in turn eliminates the rotational capacity of the device.
Many cases of such types of failures have forced the design authorities to revert back to
traditional steel bearings.
33. BRIDGES & BEARINGS
However, in India no such failure has been reported so far.
All these defects/deficiencies in the confined elastomeric pad element in
a pot bearing cannot be detected after installation and transfer of full load,
unless the bearings are removed and elastomeric pressure pad is taken out
for inspection of the elastomeric element, metallic cylinder and piston.
For the same reason, the behaviour of the elastomeric rotational element
cannot be checked visually during proof load and movement testing at
manufacturer’s works.
Therefore, a lot of care has to be exercised at the manufacturing and
inspection stage.
34. BRIDGES & BEARINGS
Maintenance of Pot-cum-PTFE bearings
1. The Pot-cum-PTFE bearings are designed and manufactured so as to make it almost
maintenance free. However, the surrounding area of the bearings shall always be kept clean
and dry to avoid damage to the bearings.
2. Suitable easy access to the bearing shall be provided for inspection and maintenance.
Provision shall be made for jacking up the superstructure so as to allow repair/replacement of
the bearings. 135
3. Inspection of bearing at site is required from time to time to ascertain the performance of
the bearings. Periodic nominal maintenance of bearing shall be carried out in order to ensure
better performance and longer life.
The bearings are required to be inspected at an interval of one year for the first five years and
at an interval of two years thereafter.
However, the bearings shall also be examined carefully after unusual occurrences, like
movement of abnormal heavy traffic, earthquakes, cyclones and battering from debris in high
floods.
35. BRIDGES & BEARINGS
RESULTS AND ACTIONS
The results of every inspection to be recorded in the inspection report and shall
be classified in each case into the following types of action: i) No action
ii) Further measures/long-term monitoring or design analysis needed (e.g.,
considering extreme temperatures/ exposures, variation of loads, etc.).
iii) Minor repair works e.g. cleaning, repainting etc.
iv) Repair or replacement of entire bearing or parts of the bearing.
In case of defects where the cause of necessary actions cannot be determined
by the inspecting person or the responsible bridge engineer, the design
engineers/ manufacturer should be consulted.
36. BRIDGES & BEARINGS
New Delhi, Aug 6 | Updated On: Mar 12, 2018
Delhi’s Airport Metro Express will miss its August-end deadline set by the
government for resumption of services as the repair work undertaken
by Delhi Metro on the civil structure is expected to end only by mid-
September.
The repair work on the bearings that serve as an interface between the
pillar and girder is being undertaken by the
Delhi Metro in coordination with authorities of the Reliance Infra-led Delhi
Airport Metro Express Pvt Ltd that runs the line.
37. BRIDGES & BEARINGS
Nearly 500 of the 2,100 bearings were found to be faulty and
the Delhi Metro in consultation with the Indian Railways
has come out with specific designs to repair or replace the faulty
bearings.
“The 500 bearings would either be replaced or repaired according
to their conditions.
The work is expected to end by September 20.
Once we are done with the work, we will hand over the line to the
concessionaire”, a top source told PTI.
This effectively means the line will miss its August 31 deadline set
by
the Union Urban Development Ministry when it had announced
that the route was being temporarily closed down for operations
38. BRIDGES & BEARINGS
REPAIRS OF BEARINGS AT DELHI AIRPORT METRO
The Freyssinet Prestressed Concrete Co. Ltd., 6B, 6th floor, Sterling Center, Dr. Annie
Besant Road, Worli, Mumbai-400018. Tel. +91-22-43229500 Fax. +91-22-24938461,
e-mail-freyssinet@fpccindia.com,http://www.freyssinet-india.com/
New Delhi: After the hullabaloo over defective bearings found on Airport Metro
Express line, Delhi Metro is not taking any chance and plans to not only change the
500-odd defective bearings but also the grouting underneath.
“We will replace the 500-odd bearings found defective and also the grouting
underneath. Instead, to ensure quality control, we are going to put steel pedestals
under the bearings,” said a senior Metro official.
The decision comes after the joint inspection committee of the Delhi MetrO
39. BRIDGES & BEARINGS
INTRODUCTION
Delhi airport Metro Express lane a part of the DMRC project
was constructed by M/s. IJM Infraprojects Ltd.
This section of the metro lane was commissioned in year October 2010.
At around June 2012, vibrations at curvature locations were noticed by train-
motormen and this had been brought to the knowledge of DMRC higher
authorities.
Metro lane of this section was immediately discontinued for traffic and
inspection of same was carried out to find the cause.
Due to discontinuation of this section, the transportation system in this zone
was affected creating problems for commuters.
Hence DMRC appointed FPCC to complete this challenging job to be completed
within least possible time with quality work
40. BRIDGES & BEARINGS
Action for Remedial Measures:
After inspection, some problems were found with existing bearings.
DMRC has decided immediately to carry out thorough inspection &
repairing/replacement of these bearings.
DELHI Airport Metro awarded this job to specialized contractors to execute the
repair work of bearings of the above section. Approx. 86 spans for AMEN03
section-Pier 186 to pier 271 were lifted and bearings were repaired/replaced by
new ones after necessary repair and providing a suitable solution for same.
The challenging feature of this project was to complete the job within the
allotted time with quality work.
41. BRIDGES & BEARINGS
Following key-personnel were involved in this project.
Client : M/s. Delhi Metro rail Corporation (DMRC) Mr. A.S. Bisht
Design Consultant : M/s. Systra International Mr. Mathews
PMC : M/s. TUV Mr. Tyagi
Contractor :
M/s. The Freyssinet Prestressed Concrete Co. Ltd. Mr. Sunil Dayal (
General Manager) Mr. Raja Jawale (AGM-Project In charge) Mr.
N.K.Mehta (Sr. Project Manger)
42. BRIDGES & BEARINGS
Defects in Delhi Metro Works
the Concessionaire has noticed
certain defects in the Delhi Metro
Works,
which are affecting the performance
obligations of the Concessionaire
under the Concession Agreement.
43. BRIDGES & BEARINGS
A non-exhaustive list of the defects ("Defects")
which have created unsafe conditions for the performance of the
Concessionaire‟s obligations under the Concession Agreement are:
Extensive cracks in the bearing pedestals;
Large chunks of fillings, at the top and bottom of
bearings, crushed and several pieces having already fallen;
Displaced and tilted bearings;
Pot bearing movement restricted by steel strips bolted
to top and bottom of the bearings;
44. BRIDGES & BEARINGS
Damaged girders;
Severe damages to pier caps.
Upon becoming aware of the Defects, further inspections were carried out (without
having the original,„as-built‟ and other relevant designs and drawings which DMRC,
despite being demanded, has not provided) and a preliminary investigation report was
accordingly prepared by our internal expert team.
The preliminary investigation report indicates that the Defects, being latent/inherent
defects in the Delhi Metro Works,
have arisen solely due to poor workmanship, faulty construction methodology and
deficiency in the design of the Delhi Metro Work
Damaged bearing pads;
Dangerous movement of the girders;
45. BRIDGES & BEARINGS
s As obligated under the Concession Agreement,
the Concessionaire has immediately notified Delhi Metro on May 17, 2012
regarding the occurrence and existence of the Defects which have resulted in
the unsafe conditions
for‟ the operation‟ of the Project A copy of the said investigation report is
enclosed herewith and marked
Copies of the correspondence exchanged between the Concessionaire and
Delhi Metro till date in this regard are also annexed herewith and marked .
The Defects in Delhi Metro Works:
were not apparent at the time of handing over of the Site (including the handing
over in parts/sections) to the Concessionaire;
were not capable of being noticed/ identified at the time of takeover due to their
latent/ inherent nature; and
affects the operation of the entire Project.
46. BRIDGES & BEARINGS
Delhi Metro Works were handed over to the Concessionaire on an "as is
where is" basis; and
Defects in the Delhi Metro Works are latent/ inherent defects and have
arisen solely due to poor workmanship, faulty construction methodology
and deficiency in the design in the Delhi Metro Works,
it was not possible for the Concessionaire to notice/ identify
the Defects (despite undertaking the inspections) nor could the Defects
have been noticed at the time of taking over the possession of the Delhi
Metro Works.
At this juncture, it is important to highlight an observation of
Shri A. K. Gupta, Additional Member (Works), Railway Board,
which he has made in the meeting held at the Ministry of Urban
Development on July 2, 2012
and also noted in the MOM and annexed herewith as Annexure which
observes as below: "... in the railway systems,
visual inspection of bearing are carried out once in a year,
47. BRIDGES & BEARINGS
while detailed inspection once in five years and life
of bearings is around 15 years" (emphasis applied)
In view of the above observations by one of the most acknowledged domain
experts,
it is clearly evidenced that, in standard practice, the quality of the bearings
(which is also one of the part of the Defects in the Delhi Metro Works)
is at least of such standard that it needs an inspection only once in 5 years.
Since the Project has been commissioned early last year only,
there was no reason to conduct the detailed inspection of the bearings and
other Delhi Metro Works
48. BRIDGES & BEARINGS
either at the time of taking over the possession or
otherwise, except as provided in the Concession
Agreement.
We have been represented and were under a bonafide
impression that
the Delhi Metro Works will be of such quality and
standards that they shall be capable of allowing
the Concessionaire to perform its obligations at least for
the Concession Period in accordance
with the terms of the Concession Agreement.10. It is
further pertinent to point out here that the
49. BRIDGES & BEARINGS
Concessionaire did not have any control or say of any nature
whatsoever inter-alia in the design,
engineering, construction and testing of the Delhi Metro Works, and
thus, the sole responsibility for Delhi Metro Works rests with
DMRC.
It is pertinent to note that these Defects in Delhi Metro Works
have been acknowledged and accepted by DMRC,
including in its letter nos. DMRC/20/11/AP/2011 /P1/33/3654 dated
June 2, 2012,
DMRC/20/11/AP/2012/ P1/33/3657 dated June 6, 2012 and
DMRC/20/11/ AP/2012/P1/33/3666 dated June 12, 2012.
These letters are annexed herewith as Annexure D.
50. BRIDGES & BEARINGS
REFERENCES
Following codes & standard were referred
for the above procedure of repair work of bearings.
Morth Specification
Relevant Drawings of Bearings & girder sections
Specification of Bearings
51. BRIDGES & BEARINGS
FPCC inspected one by one girder and observation details were noted
down.
Available tolerance allowed to be maximum 1mm.
So we have to adopt suitable method to replace the bearing with
proper pedestal within allowable tolerance.
Heights and other necessary dimensions were taken to fix the jacks
for lifting
52. BRIDGES & BEARINGS
ACHIEVEMENT
The core achievement of FPCC was the completion of the project
with set targeted time,
with due quality work,
as per requirement of the DMRC,
despite of many challenging and increased quantum of repair work.
There was a space constraint at many locations
where special precautions were taken as per requirement.
54. BRIDGES & BEARINGS
•. It is WSDOT's policy to remove and replace
nonfunctionin g or seismically vulnerable
tipping rocker bearings to extend the service
lives o f existing bridges.
• Details o f three recent bearing replacement projects i n Washington State are
presented. Case studies describe three different Ufting approaches:
• direct bearing o n truss gusset plates, the use o f a jacking beam as a pry bar wit h a
mechanical advantage o f 2 to 1, and the use o f jacking diaphragms placed between
the ends o f plate girders.
• WSDOT shares responsibility fo r the success of the liftin g operation by including
details i n the plans fo r the
55. BRIDGES & BEARINGS
Most practical Ufting procedure on the basis o f past experience.
As the owner WSDOT is concerned that no damage to the bridge should
occur during a lfting operation.
The contractor may propose an alternate liftin g procedure.
Generally, jacking under Uve load traffic is not recommended.
Hydrauli c jacks are used as a means of Ufting bridges so that defective or
frozen bearings can be removed.
Jacks should be sized fo r a minimu m o f 1.5 times the calculated lifting
loads to account fo r discrepancies between hydraulic gauge readings and
calculated
56. BRIDGES & BEARINGS
lifting loads.
The gauge readings indicate that heavier liftin g loads occur and may be attributed to
the in - creased force required to break the bond caused by heavy rusting of the roller
nests, internal friction in the jacks caused by binding, or faulty gauges.
I n the first case study, epoxy was used as a leveling course fo r uneven gusset plates.
This was the first time that WSDOT specified an epoxy as a means o f uniformly
distributing lifting loads.
To prevent spalling, the epoxy leveling course should be confined by steel bars along
each side for a depth equal to one-half height o f the leveling course.
Bridge bearing replacement is simplified if it is coordinated wit h rehabilitation projects.
57. BRIDGES & BEARINGS
As shown i n the second case study, it was easier to lif t the bridge fro m
above wit h jacking beams after the concrete deck was removed because
the deck accounted fo r 70 percent o f the dead load.
Smaller jacking beams and jacks were used because o f the reduced
dead load.
Replacement bearings include multirotationa l disc bearings, fabric pads
wit h TFE and stainless steel sliding surfaces, elastomeric bearings, and
lead-core isolation bearings.
Elastomeric bearings show promise as replacement bearings because
they are corrosion resistant, du - rable, easy to install, maintenance-free,
and more economica l than other bearing types.
Maximu m design loads fo r replacement bearings, costs fo r
replacement bearings, and costs fo r liftin g bridges are given.
58. BRIDGES & BEARINGS
WSDOT, and were checked by the author.
The Snohomish River liftin g and bearing replacement project was designed by
Jugesh Kapur and was checked by John LaBranche, WSDOT.
Rick Liptak , WSDOT, was the Bridge Technical Advisor fo r the Snohomish River
Bridge project.
Progressive Contractors, Inc., di d the liftin g and bearing replacement o n the
Puyallup River and Snohomish River bridges.
Mowa t Construction Company was the contractor fo r the Kalama River Bridge
bearing replacement.
The author thanks WSDO T fo r support i n preparing this paper.
The bearing replacement designs were prepared under the direction o f Alla n H .
Walley, forme r WSDO T Bridge and Structures Engineer, and M . Myin t Lwin ,
current WSDO T Bridge and Structures Engineer.
Their support and encouragement are very much appreciated.
59. BRIDGES & BEARINGS
REFERENCES
1. Redfield, C , and C. Seim.
Pot Bearing Replacements— Two Case Studies: Cline Avenue Interchange and 1-285/ 1-85 Interchange.
Joint Sealing and Bearing Systems for Concrete Structures, Vol. 2, SP-94.
American Concrete Institute, Detroit, Mich., 1986, pp. 817-823.
2. Van Lund, J. A. Jacking Steel Bridge Superstructures in Washington State.
In Transportation Research Record 1319, TRB, National Research Council, Washington, D.C., 1991, pp.
94-101 .
3. Structural Lifting Operations. Bridge Special Provision, Washington State Department of
Transportation, Jan. 1991.
4. Orr, J. Planning, Knowledge Keys to Safe Bridge Lifting. Roads & Bridges, Vol. 26, No. 4, April 1988, pp.
85-87.
5. Standard Specifications for Highway Bridges, 15th ed. AASHTO, Washington, D.C., 1992, pp. 294-299.
61. BRIDGES & BEARINGS
•TYPE OF BEARINGS IN RAILWAYS
• Elastomeric Bearing Vulcanized rubber is also referred to as elastomer.
• Deterioration of Rubber Bearing The vulcanization (or curing) [heating rubber
with sulfur results in three-dimensional crosslinking of the rubber molecules
bonded to each other by sulfur atoms] of the compounded rubber is usually
carried out under pressure in metal moulds at a temperature of about 140°C.
• Polymer materials used for both interior and exterior applications are subject to
photodegradation when exposed to ultraviolet light.
• Photo-degradation is a process whereby the polymer chains in the product break
down due to exposure to UV radiation.
• The UV light, which makes up about 10% of sunlight is an electromagnetic
radiation.
63. BRIDGES & BEARINGS
Destressing of Elastomeric Bearing Why?
Destressing of elastomeric bearings will be determined by the information about its
temperature at the time of installation.
[Shear modulus G is considered 0. 9 MPa at 230 C-min. 0. 8 MPa, max. 1. 2 MPa] Range of
temperature considered in design is 320 C for Pune region.
If installed at extreme temperatures, the destressing of non-laminated elastomeric bearing
pad is required.
However, destressing of laminated elastomeric bearing is not required unless otherwise there
are pressing reasons. When?
Destressing of elastomeric bearing pad shall be attempted at mean temperature of the region
where it is installed so that t is not exceeded. How?
Special type of jacks having locking arrangement or safety protection to prevent a lifting
mechanism of a jack from completely retracting in the case of a mechanical failure in the lifting
mechanism.
[Jack capacity should include Dead load + SIDL + Live load]
65. BRIDGES & BEARINGS
Inspection Items of Elastomeric Bearing Failure Modes Pad
deterioration Slip Creep/Bulging Aging Description Inspection Items Large shear
strains Splitting and tearing at edges when the bearing is without sole plates or
other mechanical devices & paraffin wax added to the rubber for Ozone
protection walking of bearing from its original position [Bond between rubber
and the sole plate] Creep is significant for Electrometric Bearings.
Bonded sole plates at the top and bottom of the bearing caused about
Excessive bulging of the pad 50% less creep.
Bearings with a higher shear modulus have higher creep.
Aging generally affects the thin outer layer of the bearing.
Old bearings which are exposed to severe temperatures will experience a
change in the shear modulus.
Cracked edges (especially in bulges)
68. BRIDGES & BEARINGS
Inspection Items of Elastomeric Bearing Failure Modes
Description Inspection Items Delamination Occurs between the metal shim and
rubber due to low or absent bond Delamination between rubber and metal Poor
quality A major cause of failure.
Bearings will be damaged if the bridge superstructure rotates about any other
axis than the line of the bearings Splitting and tearing at edges Delamination
between rubber and metal Increase in pad length at the pedestal Crushing
Compressive failure in the bearing.
Hard to detect and noticeable by voids at the bottom of the bearing.
Voids beneath the pad Diagonal tension strains Caused by the combined effect
of compression, shear and rotation Increase in pad length at pedestal Height
differences in the pad or internal layers Caused by large shear strains Layer
heights/thickness should be the same Rupture of reinforcement
69. BRIDGES & BEARINGS
INSPECTION OF BEARINGS IN RAILWAYS Inspection
Frequency for newly commissioned Metro Plain Line
First Inspection after 6 months of commencement of dynamic loading.
Second Inspection after 12 months of commencement of dynamic loading.
Subsequently, annual inspection is recommended.
Cross.Over/Scissors Cross-Over First Inspection after 3 months of
commencement of dynamic loading.
Second Inspection after 6 months of commencement of dynamic loading.
Third Inspection after 12 months of commencement of dynamic loading.
Subsequently, annual inspection is recommended.
71. BRIDGES & BEARINGS
BEARING INSPECTION PARAMETERS
Inspection Parameters Position of bearing
BEARING INSPECTION PARAMETERS Inspection Parameters Cracking and
tearing of elastomer
BEARING INSPECTION PARAMETERS Inspection Parameters Separation of
rubber from steel lamination
BEARING INSPECTION PARAMETERS Inspection Parameters Excessive shear
[Shear deformation more than 50% of height of elastomeric pad]
TYPE OF BEARINGS IN RAILWAYS Inspection Parameters Excessive bulging
[Compression more than 5% of height of elastomeric pad]
TYPE OF BEARINGS IN RAILWAYS Inspection Parameters Off-loading of one edge
due to excessive rotation
73. BRIDGES & BEARINGS
•TYPE OF BEARINGS IN RAILWAYS
Inspection Parameters Partial contact of the elastomeric bearing with the
adjacent concrete surfaces
• Incorrect dimensions of the tapered attachment plates or cambers
outside the predicted range
• Incorrect or out-of-tolerance slope of the mortar pad surface
• Inadequate vertical load on the bearing under permanent effects
SPECIAL CASES POT-PTFE Bearing Polyoxymethylene (POM) Internal seal
failure = elastomeric disc extrusion :
Special attention to very flexible structures and to large sized bearings
74. BRIDGES & BEARINGS
FIRST ACTIVITY Cleaning of pier cap
[Common problem in Indian Metros]
PREPARATION OF BEARING REPAIR/REPLACEMENT Access Plan for bearing repair/replacement
[Scaffolding and Cranes] Depend on elastomeric bearing and POT PTFE bearing (Heavier)
PREPARATION OF BEARING REPAIR/REPLACEMENT Traffic Diversion Plan Traffic Marshals to be
deployed with traffic batons Police permission shall be obtained for partial/full blockage of road as
per traffic plan
PREPARATION OF BEARING REPLACEMENT Safety Plan • All site personnel shall be provided with
helmet, boots and other personal safety devices. • All safety precautions for working on height shall
be taken. • Tool box talk shall be performed before commencement of work. • Working area to be
barricaded and caution tape to be tied around.
PREPARATION OF BEARING REPLACEMENT Organization Chart [Roles and Responsibilities] [Head
Civil] Roles and Responsibilities shall be defined and issued in writing to avoid duplication and/or
confusion at the time of taking decisions [Safety Officer] [Civil] [Track] [Interface] [Traffic]
75. BRIDGES & BEARINGS
• PREPARATION OF BEARING REPLACEMENT
Expert Manpower [Foreman and skilled labourers]
Sr. No. Backbone to successful completion of repair/replacement
activity within time Only experienced manpower should be
deployed for operation of jack and installation/replacement of
bearing Expert Team Qty. Unit 1 Jack operation team Foreman
skilled technicians 1 no. 6 no.
Bridge bearing installation/replacement 2 experts Foreman skilled
technicians 1 no. 5 no. 3 Scaffolding team Foreman Labourer
Electrician 1 no. 4 no. 1 no.
77. BRIDGES & BEARINGS
•PREPARATION OF BEARING REPLACEMENT
Interface Plan [Track/OHE/Signalling/Operation/Non-Fare Box Revenue/Railway]
1. Track
2. OHE
3. Signalling
• Track, OHE & Signalling teams shall take site measurements in advance at problem location.
The respective installation at the problem site shall be inspected and kept under observation
during bearing replacement work. Measurements shall be recorded/corrected by respective
department
• CMV shall be loaded with all required equipment and shall be moved to problem site
immediately after receiving information from O. C. C. in the night of bearing replacement work.
4. Non-fare box revenue
78. BRIDGES & BEARINGS
• Operation Any attachment/cable/equipment of advertisement shall
be removed/decommissioned in advance.
• CMV induction/withdrawal plan, Trial run train plan, Permit To Work
etc shall be planned with Operation department.
The maximum possible block hours shall be obtained and utilized
. • OMS shall be made ready in trial run train for recording ride index
after bearing repair/replacement.
79. BRIDGES & BEARINGS
• PREPARATION OF BEARING REPLACEMENT
• Check List:
• Safety & Traffic S. No. Safety and Traffic check lists shall be signed before
commencement of work [Mock Drill shall be conducted] Items
• 1. All workers wearing Personal Protective Equipment
• 2. Emergency medical kit and other emergency facilities are provided at
site
• 3. All lights are properly covered using insulated wires, Halogen lamp
and Hand lamps with wire mesh covering
• 4. Safety officer/supervisors are on constant duty at site
• 5. Proper warning sign boards/instructions boards in Hindi and English
provided at site
• 6. Proper Staging done to provide working platform.
80. BRIDGES & BEARINGS
• 7.Hydra Crane placed at safe angle and secured footing.
• 8. Electric wires/ equipment kept at safe distance.
• 9. Scaffolding on firm ground anchored
• 10. Operators of Jacks shall be trained and having certificate.
• 11. Safety belt provided to all workers working at height. Yes No.
82. BRIDGES & BEARINGS
• PREPARATION OF BEARING REPLACEMENT
• Check List: Inspection Plan Sr. No. Inspection Plan shall be prepared and
signed before commencement of work Description
• 1. Method Statement approved.
• 3. Centering and Scaffolding approved.
• 4. Girder Lifting equipment (jacks) calibration.
• 5. Hydra Crane Third party certificate Form 11.
• 6. Competency certificate for Hydra operator
• 7. Track machines in working condition.
• 8. Access & platforms provided.
83. BRIDGES & BEARINGS
• 9. Safety and Traffic arrangement adequate.
• 10. Adequate lighting provided.
• 11. All bolts of bearing tightened as per requirement.
• 12. Track geometry
• 13. Trial run YES NO NA
85. BRIDGES & BEARINGS
PREPARATION OF BEARING REPLACEMENT
List of Tools & Equipment Exhaustive List of Tools and Equipment shall be
prepared in consultation with foreman
Sr. No. Description 5 Tools and consumables Manila rope 16 mm dia.
Sliding wrench spanner Hammer 3 kg Hammer 2 kg Katni rod D-spanner
46 mm dia Ring spanner 46 mm dia Torch Rechargeable type Halogen
Light LED (100 watt) Hand Gloves cotton with rubber squares Mobil Oil
for bolts Grease for bearing (Anabond 662) Gas cutting set Portable
welding machine M 30 Hexagonal bolts WD-40 derusting agent 6 2 nd
generation Hydra (14 T) with operator and helper D-shackles (8 nos. ) and
slings (4 nos. ) Steel scale (6" and 12") Qty. Unit 10 m 2 no. 4 no. 15 pair 2
ltr 2 kg 1 no. 2 no. 16 no. 5 no. 3 days 2 no.
86. BRIDGES & BEARINGS
PREPARATION OF BEARING REPLACEMENT
List of Tools & Equipment
Sr. No. Description 7 Scaffolding with working platform (cup-lock type)
load carrying capacity (278/0. 63 x 0. 63) kg/sqm Exhaustive List of Tools
and Equipment shall be prepared in consultation with foreman Concrete
surface preparation Hand Grinder Blower Pencil grinder Qty. Unit 700
kg/sqm bay width, length=500 mm, lift height=1200 mm, 75 mm dia pipe
Platform with required capacity; standard baseplates 8 Auto level
Measuring Staff (1 mm LC) SLR camera Laser pointer Dial gauge Steel
scale (6" and 12") Radio sets 9 Robel bolt tightening machine
Bosch/Makita bolt tightening machine Gauge X-level; Versine Kit Spare
components of Vossloh 336 Shims (2 mm, 3 mm); Eccentric bushes 10
CMV/RRV Passenger Car; Utility Vehicle 1 no. 2 no. 3 no. 2 no. LS 20 no. 1
no. 2 no.
87. BRIDGES & BEARINGS
PREPARATION OF BEARING REPLACEMENT
Quality Assurance Plan of Bearing
Sr. No. Componen Characteri Mode of t& stic Inspection Operation Checked
Inspection By Freque Reference Accepta Formats ncy of Document & Record Checks
Norms Remarks Manufact Insp. urer Authority
Bearing Raw Material Bearing Material Condition Identificatio n & Corelation
Material Condition Visual Inspection :
Pitting, rusting any other surface defects.
Mageba Metro 100% Receipt document Receipt to be IRC 83 and TC & document
verified Part- II & Statemen and Test before certificate installation Material Test
100% Manufactu rer TC & Statement of Material Test IRC 83 Part-III Manufacturer
TC & Statement of Material Test to be verified before installation
89. BRIDGES & BEARINGS
PREPARATION OF BEARING REPLACEMENT
Trials and Approval of Cementitious Grout Water/Binder ratio: 0. 19 •
Shall be fit for use in machine foundation i. e. tested under dynamic
condition
• Grout should have the flexural strength properties (9 MPa @28 days)
Bonding with old concrete (good adhesion property) Time Compressive
Strength N/mm 2 20 mins 10. 8 23. 6
• Curing compound e. g. Concure WB
• Sikadur 52 Epoxy, Master. Inject 1315 (Concresive 1315)
90. BRIDGES & BEARINGS
JACKING POINTS Precast Double U-Girder Steel Truss
TYPICAL CASE OF CONGESTED LOCATION Scaffolding and lifting
arrangement on pier cap
JACK POSITIONING Spherical Saddle Type jack
91. BRIDGES & BEARINGS
BEARING REPAIR/REPLACEMENT
Method Statement of Replacement/Repair of Bearing Condition
Survey: Jacking of girder:
Survey should be done for condition of nuts and bolts in advance.
This will include cleaning, derusting, loosening and retightening of
nuts in case of POT bearing. WD-40 de-rusting agent should be used.
2 nos. of jacks having required capacity on supporting MS plates
shall be positioned at defined jacking locations.
92. BRIDGES & BEARINGS
2 nos. of similar spare jacks shall also be kept ready at designated
locations.
MS plates and wooden blocks shall be placed at designated
locations in just flushing condition.
All four jacks shall be tested under full load condition for 5 hrs
before bringing to site.
Jack shall also be operated one day in advance to lift the girder by 1
mm to 5 mm for de-bolting and loosening the upper wedge plate.
93. BRIDGES & BEARINGS
BEARING REPAIR/REPLACEMENT
Method Statement of Replacement/Repair of Bearing
Measurement of Track geometry: Other miscellaneous works: Rail levels on either side
of problem bearing for 50 m @5 m interval shall be measured using Auto-level.
Other track parameters shall also be recorded using gauge-cross level and versine kit.
New bearing shall be shifted on centering at designated location with the help of D-
shackles, slings and hydra crane a day before bearing replacement operation.
Halogens shall be placed on pier cap at predetermined locations for illumination
during bearing replacement operation.
Electric connection should be checked for confirmation of power supply.
All the track/OHE/Signalling related tools shall be loaded in CMV or shifted to
platform if problem bearing is near station.
94. BRIDGES & BEARINGS
• BEARING REPAIR/REPLACEMENT
• Method Statement of Replacement/Repair of Bearing Commencement of operation:
Monitoring of bridge/track behavior: Track will be accessed only after obtaining
necessary PTW from Station Controller.
• The area under operation shall be illuminated immediately. Jacks should be
commissioned.
• Hydra crane shall be positioned after barricading the area.
• Viaduct/Bridge span shall remain under continuous surveillance during bearing
replacement operation.
• Specifically all four bearings of said span shall be kept under watch for any unusual
occurrence like movement, displacement, slippage etc.
• In case of any unwarranted observation, the operation of bearing replacement shall be
suspended and situation shall be analyzed thoroughly.
• If things are under control then operation shall be resumed.
95. BRIDGES & BEARINGS
BEARING REPAIR/REPLACEMENT
Method Statement of Replacement/Repair of Bearing Loosening of rails: Girder lifting
All the 4 rails shall be loosened for full span of problem girder and 15 m on adjacent
span of problem pier cap.
Two Robel machines/sufficient Pan pullers shall be pressed into action.
Autolevel shall be kept ready to measure rail levels post operation for complete length
opened @5 m interval.
Top plate nuts of bearing shall be opened immediately after passage of last train.
Girder shall first be lifted by 5 mm to disengage bearings from girder.
Subsequently, girder will be lifted upto 50 mm by synchronized operation of jacks after
all the rails are loosened.
Another set of wooden blocks shall be inserted to prevent fall of girder in case of Jack
failure.
In case of elastomeric bearing, girder lifting can be restricted to 35 mm.
97. BRIDGES & BEARINGS
• BEARING REPAIR/REPLACEMENT
• Method Statement of Replacement/Repair of Bearing removal:
• Bearing placement: Bottom bolts of POT bearing shall be opened and removed. Bearing is
then pushed outward slowly to remove it from its position. 2 mm GI plate fitted wooden
block shall be placed on pier cap flushed with concrete pedestal to reduce friction while
removing bearing from its position.
• Sling shall be fastened around bearing and in between top and bottom plate to pull out
from its position.
• Once the bearing comes out of pier cap, it should slide on GI plate wooden block and then
lowered to ground.
• New bearing is then lifted using D-shackles, slings and hydra crane and kept on GI sheet
wooden block.
• Then it is pushed on its position on concrete pedestal by gradual pushing and positioning.
• Bearing shall be bolted once placed on its position.
98. BRIDGES & BEARINGS
• BEARING REPAIR/REPLACEMENT
• Method Statement of Replacement/Repair of Bearing Girder lowering:
Tightening of rails:
• Girder lowering shall be commenced and completed gradually avoiding
any risk of girder misalignment.
• Nuts shall be tightened to make it integral part of girder.
• Nuts of other bearing shall also be tightened.
• The locking plates of bearings shall be removed.
• All 4 rails shall be tightened using Robel machines/Pan pullers.
• Versine, gauge and cross-levels shall be corrected and recorded.
• If time permits rail level shall be recorded using Auto-level.
99. BRIDGES & BEARINGS
• BEARING REPAIR/REPLACEMENT
• Method Statement of Replacement/Repair of Bearing
• Trial run after repair/replacement: PTW can be given for 4 hrs Effective
working during 3 hrs All the bearings of problem span and problem pier
cap as well as track shall be inspected and certified for trial run.
• Trial run on bridge by CMV/Train shall be conducted before certifying the
bridge and track for regular operations.
• OMS readings to be checked for verification of tolerances.
• Speed restriction of 25 kmph on viaduct/bridge shall be imposed till the
performance of replaced bearing is reviewed and approved by the
Competent Authority.
100. BRIDGES & BEARINGS
BEARING REPLACEMENT Things to remember
• For elastomeric bearings, the top and bottom faces of the
bearings must be in full contact respectively with the superstructure
element being supported, and with the underlying support surface,
prior to opening the bridge to traffic.
• Uneven contact with the adjacent surfaces and inadequate
pressure on the bearing resulting in bearing slippage or “walking”.
• The cyclic movement that occurs with thermal variation can result
in a “caterpillar” walking action in the cover layer of the bearing.
102. BRIDGES & BEARINGS
• BEARING REPLACEMENT Things to remember
• • Tolerances for installation of elastomeric bridge bearings
• [RMS SPECIFICATION D&C B 284: 2018]
• Bridge bearing replacement agencies
• SCON INFRASTRUCTURE,THANE WEST, THANE, MAHARASTRA, GST-
27ACIFS5757J1ZH
103. BRIDGES & BEARINGS
BEARING REPLACEMENT Things to remember
• Minimum thickness of steel wedge plate shall be 20 mm.
• Maximum thickness will vary due to inclination of girder.
• Apprx. Wt. is 35 kg, thus, safety shall be ensured while handling
such plates during bearing replacement operation.
• Steel wedge plate tolerance +/- 0. 5 mm.
• Length of steel plate will be 50 mm more than elastomeric bearing
at all sides.
rade of steel shall be suitably selected.
104. BRIDGES & BEARINGS
• BEARING REPLACEMENT Things to remember
• • Contact area of wedge plate with bearing and girder shall be shot
blasted.
• • In case of elastomeric bearing rectification/replacement, grouting
thickness shall be determined after carrying out back calculation with
respect to slope of wedge plate and rail level.
• • Jacks must be in locked state during rectification/replacement activity.
• Installation tolerance shall be less than 2 mm.
• • Weight of girder shall be calculated correctly taking into account weight
of SIDL.
105. BRIDGES & BEARINGS
• BEARING REPLACEMENT Things to remember
• • In case of steel truss bridge, weight shall also include the deck RCC in
addition to the weight of steel span and SIDL.
• SIDL shall be correctly calculated.
• • Jack capacity shall be decided on conservative side. Retract/Closed
height and stroke of jack shall be site specific.
• • Spherical Saddle Type Jack shall be selected to negotiate the girder
slope. Misalignment of girders can be avoided.
• • To avoid difference in stiffness all adjacent bearings on same line of
support shall also be replaced.
107. BRIDGES & BEARINGS
LIST OF REFERENCES
1. IRS- Steel Bridge Code: Code of Practice for design of Railway Steel bridges. 2. IRS - BI :79: Code for
design of steel bridges, Research Design and Standards Organization, Indian Railways, Lucknow, India.
3. Bridge Rules, Ministry of Railway (Railway Board)
4. IRC: 83 (Part I): Standard specification & code of practice for road bridges, Part I - 1982 Metallic
bearings, Indian Roads congress, New Delhi, India.
5. IRC; 83 (Part II): Standard specification & code of practice for road bridges, part II- 1987 Elastomeric
bearings, Indian Roads Congress, New Delhi, India.
6. IRC; 83 (Part III) : Standard specificaions and code of pracive for road bridges part III-Section IX,
Bearings POT, POT Cum PTEF, PIN and metalic guide bearings Indian road congress, New Delhi, India.
7. UIC 772 - RC: Code for the use of rubber bearings for rail bridges - 1969, International Union of
Railways, Paris, France.
8. BS: 5400 : Steel, concrete & composite bridges, Section 9.2 - 1983 specification for materials,
manufacture and installation of bridge beariangs, British Standards Institution, London UK.
108. BRIDGES & BEARINGS
9. BS: 5400 : Steel, concrete & composite bridges, Section 9.2 -
1982 specification for materials, manufacture and installation of bridge beariangs, British Standards
Institution, London UK.
10. ORE Report D - 60 Application of rubber for bridge supporting plates
11. Proceedings of International Conference on Bridges and Fly over bridge bearings - National
cooperative high way research programme synthesis of high way practice.
12. Concrete Bridge Practice - Analysis, design and economics - By V. K. Raina
13. AASHO : Standard specification for highway bridges, The American Association of State Highway
Officials, Washington, U SA.
14. Retention of old MG bridges for Heavier BG loading by use of Elastomeric bearings’’ By S.R.
Agarwal and Adesh Shrama International Seminar on Failures, Rehabilitation and Retrofitting of
Bridges & Aqueducts, IIBE, 17- 19 Nov. 1994 Bombay.
15. Internet site : http://www.new-technologies.org/ECT/ Civil/lud.htm
16. Internet site : http://ww.en.wikipedia.org
17. Design of sliding and fixed POT-PTFE bearing for 76.2 m for HMLS - RDSO, Lucknow
109. BRIDGES & BEARINGS
18. American Iron and Steel Institute:
Steel Bridge Bearing selection and design guide 19.
Journal of Bridge Engineering:
Efficiency of Seismic Isolation for Seismic retrofitting of heavy substructured bridges. Vol.10, No.10, July/August 2005 20.
Bridge Inspection and Rehabilitation –
A practical Guide by Parsons Brinckerhoff
OCEAN RUBBER FACTORY IS THE MIDDLE EASTS LEADING SUPPLIER OF TECHNICAL RUBBER PRODUCTS. WITH OVER 700 EMPLOYEES
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Contact:FREYSSINET
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110. BRIDGES & BEARINGS
• REPLACEMENT OF BRIDGE ELASTOMERIC BEARINGS AT GREECE
• THE MAINTENCE AND REPAIR/REPLACEMENT WORKS OF BRIDGE BEARINGS
IN SEVERAL STRUCTURES IN ATHENS RING ROAD GREECE IS UNDER
PROGRESS.
• REPAIR OF PLINTH, RESTORATION OF CRACKED AND DAMAGED
EALSTOMERIC RUBBER USING THE CPLD VULCANIZATION PROCESS, TOUCH-
UP PAINTING OF RUSTED ANCHORING STEEL PLATES AND GROUT FILLING OF
THE GAP BETWEEN BEARINGS CONTACT SURFACES WITH THE STRUCTURE
ARE TAKEN PLACE.
• THESE SPECIALIZED REHABILITATION WORKS ARE AIMING TO RESTORE THE
PROPER FUNCTION OF BEARINGS BY MAINTENING THE ANTICORROSION
PROTECTION OF INNER AND OUTER REINFORCEMENT OF RUBBER AND
PROLONG THE SERVICE LIFE.
111. BRIDGES & BEARINGS
• ADDITIONALY, JACKING AND LIFTING OF SUPERSTRUCTURE, USING HYDRAULIC
JACKS IN SUFFICIENT NUMBER, STROKE AND LIFTING CAPACITY 45MM/250 T EACH
IS IMPLEMENTED IN CASES WHERE THE REPLACEMENT OF A MALFUNCTIONED
BEARING IS NEEDED.
• THE LIFE EXPECTANCY OF ELASTOMERIC BRIDGE BEARINGS IS CURRENTLY
UNKNOWN.BEING ABLE OT TEST A BEARING TO SEE IF IT IS NOT PERFORMING
WELL FROM DAMAGE WILL HELP US BETTER UNDERSTAND BEARING
REPLACEMENT SCHEDULES AND PLAN MAITENANCE BUDGETS MORE EFFECTIVELY.
AS PER MC MASTER UNIVERSITY ENGINEERING ADDRESS 1280 MAIN STREET WEST
HAMILTON, ONTARIO ,CANADA L8S 4L7 PHONE (905) 525.9140
• ALL RESTORATION WORKS ARE IN LINE WITH THE FINDINGS OF THE ROUTINE
INSPECTION PROGRAMME PERFORMED BY THE HIGHWAY OPERATOR IN ORDER TO
EVALUATE THE ACTUAL CONDITION OF BRIDGES AND ESTABLISH A ROBUST
INSPECTION-MAINTENANCE REGIME PROLONGING THE FUNCTIONALITY OF THE
STRUCTURAL ELEMENTS BY ENSURING PUBLIC SAFETY AND PUBLIC INVESTMENT
114. *****************************************
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M.TECH-CIVIL STUCTURES,B.TECH-CIVIL,DIPLOMA-CIVIL
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