irc.gov.in.083.2014

IRC:83-2014

(Pt. IV)

STANDARD SPECIFICATIONS AND CODE OF PRACTICE FOR ROAD BRIDGES SECTION - IX BEARINGS

(SPHERICAL AND CYLINDRICAL)

PART

-

IV

73

INDIAN

ROADS CONGRESS 2014

Digitized by the Internet Archive in

2014

https://archive.org/details/govlawircy201483

IRC:83-2014

(Pt. IV)

STANDARD SPECIFICATIONS AND CODE OF PRACTICE FOR ROAD BRIDGES SECTION -IX

BEARINGS

(SPHERICAL AND CYLINDRICAL)

PART

-

IV

Published by:

INDIAN

ROADS CONGRESS Kama

Koti

Marg,

Sector-6, R.K. Puram,

New

Delhi-110 022

August, 2014

Price

(Plus Packing

:

^ 600/-

& Postage)

IRC:83-2014

First

(Pt. IV)

Published

(All

August, 2014

Rights Reserved.

No part of this publication

translated or transmitted in

shall

be reproduced,

any form or by any means without the

permission of the Indian Roads Congress)

Printed by India Offset Press, Delhi-110064

1000 Copies

IRC:83-2014(Pt.

IV)

Contents Page No Personnel of the Bridges Specifications and Standards Committee

i

Introduction

.1

1.

Scope

2.

Definition of Product

3.

Terms

4.

Material Specification

8

5.

Design Requirements

11

6.

Manufacturing

24

7.

Acceptance, Certification and Marking

29

8.

Packaging, Transport and Storage

34

9.

.

2

of

and Intended Use

3

Reference and Symbols

Aspects Related

to

5

Bearing Performance and Installation

35

ANNEXURES Annexure-A

-

Properties of

(PTFE

or

Low

39

Friction Thermo-plastic Sliding Material

UHMWPE)

Annexure-B

-

Properties of Composite Material for Secondary Sliding Surfaces

40

Annexure-C

-

Bridge Bearing Design Questionnaire Form

42

Annexure-D

-

Ferroxyl Test for Hard

Annexure-E

-

Bearings Anchorage Design Rules

46

Annexure-F

-

Check

49

for Permissible

Chromium

.

Plating

Stresses on the Adjacent Concrete Structure

44

)

IRC:83-2014

(Pt. IV)

PERSONNEL OF THE BRIDGES SPECIFICATIONS AND STANDARDS COMMITTEE (As on 1

.

2.

January, 2014)

Kandasamy, C. (Convenor

Director General (RD) & Spl. Secy, to Govt, of India, Ministry of Road Transport and Highways, Transport Bhavan, New Delhi

Patankar, V.L.

Addl.

Director General, Ministry of Road Transport and Highways Transport Bhavan, New Delhi

(Co-Convenor) 3.

6*''

Pathak, A.P.

Chief Engineer (B) S&R, (Ministry of Road Transport

(Member-Secretary

Transport Bhavan,

)

New

& Highways,

Delhi

Members CPWD

4.

Agrawal, K.N.

DG(W),

5.

Alimchandani, C.R.

Chairman & Managing

Director,

6.

Arora, H.C.

Chief Engineer (Retd.)

MORTH, New

7.

Bagish, Dr. B.P.

C-2/2013, Vasant Kunj, 0pp. D.P.S.

8.

Bandyopadhyay,

Dr. N.

9.

Bandyopadhyay,

Dr.

TK.

Director,

(Retd.)

Ghaziabad

Stup Consultants (P)

STUP

Consultants (P)

New

Delhi

Delhi

INSDAG, Kolkata

Joint Director General (Retd.)

10.

Banerjee, A.K.

Chief Engineer (Retd.)

MoRT&H, New

Delhi

11.

Banerjee, TB.

Chief Engineer (Retd.)

MoRT&H, New

Delhi

12.

Basa.Ashok

Director (Tech.) B. Engineers

13.

Bhasin,

14.

Bhowmick, Alok

RC.

ADG

(B), (Retd.),

Managing

&

Builders Ltd.,

MoRT&H, New

Director,

&

Bridge

Mumbai

Delhi

New

Ltd.

Ltd.,

Bhubaneswar

Delhi

Structural Engg. Consultants (P) Ltd.,

'

Noida

Mumbai

15.

Bongirwar, P.L.

Advisor, L&T,

16.

Dhodapkar, A.N.

Chief Engineer (Retd.)

17.

Ghoshal,A.

Director

18.

Joglekar, S.G.

Vice President,

19.

Kand„C.V.

Chief Engineer (Retd.), MP,

20.

Koshi, Ninan

DG(RD) & Addl.

21.

Kumar, Ashok

Chief Enginee (Retd.),

22.

Kumar, Prafulla

DG

23.

Kumar, Vijay

E-in-Chief (Retd.) UP,

24.

Manjure,

Director, Freyssinet Prestressed

25.

Mukherjee, M.K.

Chief Engineer (Retd.)

26.

Nagpal,A.K.

Prof. NT,

27.

Narain,A.D.

DG

28.

Ninan, R.S.

Chief Engineer (Retd.)

29.

Pandey, R.K.

Chief Engineer (Planning),

P.Y.

MoRT&H, New

and Vice President,

(RD) & AS,

New

STUP

STUP

Consultants (P)

Consultants (P)

PWD

Secy., (Retd)

Delhi

Ltd.

,

MOST New

Delhi

Delhi

New

Delhi

(Retd.)

Mumbai

Bhopal

MoRT&H, New

MoRT&H

PWD, Concrete Co. Mumbai

MoRT&H, New

Delhi

Delhi

(RD) & AS,

New

Delhi

MoRT&H New

Delhi

MoRT&H

I

Ltd.

(Retd.)

MoRT&H, New

Delhi

Kolkata

.

IRC:83-2014(Pt.

30.

IV)

Dr. (Mrs.)

Raizada, Pratap S.

Vice President (Corporate

32.

Rao,

A-181, Sarita Vihar,

33.

Roy, Dr. B.C.

M.V.B.

New

Affairs).

Gammon

Delh

tZXeCUllVc UirtJUlUi OUllbUUllId L/UtlbUlldllCy \r) LIU. iviurnDdi

ur. o.r.

Sharan, G.

DG

36.

Sharma, R.S.

Chief Engineer (Retd.)

MoRT&H, New

37.

Sinha, N.K.

DG(RD) & SS,

MoRT&H New

38.

Subbarao,

lanuon, ividnebn rroT. 1

ridriUdVdri, r\.D.

41.

Velayutham,

42.

Viswanathan,

43.

The Executive

44.

The

Director

(RD) &

Spl.

Secy

(Retd.)

(Retd.)

Harshavardhan Chairman & Managing

Dr.

iviui

/in

1

ividiidgiiig uireciur,

DG

Director (B&S)

and Head,

Delhi

Delhi

Construma Consultancy

idiiuuri ooiisuiidnis \r)

ciigiricci ^iNciu.j iviurs

(RD) &

SS

(Retd.)

1

,

.

Delhi

Vasant Kunj ,New Delhi

RDSO, Lucknow (Civil

Engg.), Bureau of Indian Standards,

1.

Raina, Dr. V.K.

Consultant (W.B.)

2.

Singh, R.B.

Director, Projects Consulting India (P) Ltd.

Ex-Officio President,

IRC &

Director General

New

Delhi

New

Delhi

Members

(Kandasamy, C), Ministry of Road Transport and

(Road

Highways,

New

Delhi

Development) & Special Secretary 2.

Secretary General

(P)

na.,iNew ueini

«n, i\cw ueini

MoRT&H, New

7046, Sector B, Pocket 10

T.

Director,

Dellhi

lUdi

(w'liici

V.

MoRT&H, New

Corresponding Members

1.

(Pvt.]

ourgaon

35.

oy

India Ltd. iVlumbai

Senior Executive Director, M/s. Consulting Engg. Services India Lia.

oana,

Delhi

Lakshmy

31.

Dr.

New

Chief Scientist (BAS), CRRI,

Parameswaran,

(Prasad, Vishnu Shankar), Indian

New

Delhi

Roads Congress,

^

~

Ltd

IRC:83-2014

(Pt. IV)

STANDARD SPECIFICATIONS AND CODE OF PRACTICE FOR ROAD BRIDGES SECTION - IX BEARINGS PART IV (SPHERICAL AND CYLINDRICAL) -

INTRODUCTION The Bearings, Joints and Appurtenances Committee was constituted in 2011 with the following personnel:

(B-6) of the Indian

Sharan, G.

Convenor

Pandey, R.K.

Co-Convenor

Gaharwar,

Member-Secretary

Dr. S.S.

Roads Congress

Members Banerjee, A.K.

Kumar, Ashok

Bagish, Dr. B.R

Majumdar, S

Datta, R.K.

Mitra, Dr. A.J.

Deshpande,

Ninan, R.S.

V.P.

Gupta, Vinay

Ghosh,

Prof.

Patankar, V.L.

Achyut

Pandey, A.K.

Gupta, D.K.

Prakash, Suraj

Gupta, Ujjwal

Rao,

Jambekar, A.R.

Rathore, Jitendra

Khaira, V.S.

Sharma, D.D.

Kurian, Jose

Singh, B.N.

(Rep. of

Dr.

M.V.B.

RDSO, Lucknow) Invitee

Gupta, A.K.

Manjure,

Ghosh,

Panja,

S.

Ex-officio President,

A

Members (Kandasamy, C), Ministry of Road

IRC &

Director General

P.Y.

Transport and Highways,

(Road

New

Delhi

Development) & Special Secretary (Prasad, Vishnu Shankar),

Secretary General

Indian

1

Roads Congress, New

Delhi

IRC:83-2014(Pt.

IV)

Shri Jitendra Rathore prepared the

The

initial

was discussed

draft

IRC:83-2014 (Part

IV),

in

draft with the active

initial

support of Shri S. Mazumdar.

The final draft of for Road Bridges",

the meetings of the B-6 Committee.

"Standard Specifications and

Section IX Bearings (Spherical and Cylindrical),

Code

of Practice

was discussed and approved by the Bearings,

and Appurtenances Committee (B-6) held on SO**" November, 2013 for placing it in the Bridges Specifications and Standards Committee (BSS). The Bridges Specifications and Standards Committee (BSS) approved this document in its meeting held on 6*^ January, 2014. Joints

The Executive Committee in its meeting held on 9'^ January, 2014 approved this document. Finally, the document was considered by IRC Council in their 201^' meeting held on 19'^ January, 2014 at Guwahati (Assam), and approved the document for publishing.

1

Code deals

This

installation

of this

with the requirements for the materials, design, manufacture, testing,

and maintenance

code are meant

mere compliance any way of their

SCOPE

to

of Spherical

and

Cylindrical Bearings for Bridges.

The

provisions

serve as a guide to both design and construction engineers, but

with the provisions stipulated herein responsibility for the

will

not relieve the manufacturer

performance and soundness of the product

in

in

the

structure.

The

provisions of this code shall apply for operating temperature between

+ 50° Service

life

50 years with

UHMWPE.

-

15°C and

depends on the condition of rotation and translation movements posed by the Structure on Bearings. The provisions made in this code are based on an assumed working life of the Spherical Bearing upto 30 years with PTFE and of of Spherical Bearings

Bearings which are subjected to Tensile Loads are beyond the scope of this code as requiring special arrangement/configuration. Established

codes and Specifications woridwide may

please be referred for such Bearings. However

this specification

guide for general purpose

in

may be

considered as a

'

such cases.

Spherical and Cylindrical Bearings with an included angle (20) greater than 60° and 75°

beyond the scope

respectively are

of this code. In

no case the radius of curvature

shall

be

less than the projected diameter of the Spherical curved sliding surface. Sliding surfaces with a diameter of the circumscribing circle less than 1

500

mm are beyond the scope of this code.

75

mm or greater than

For cases of bearing application requiring larger

diameter of the sliding surface, established codes. Specifications and approval documents

woridwide incl.

may

please be referred. The recommendations of such document for

all

aspects

design, material, manufacturing and tolerances and testing and acceptance shall then

be applicable

in

addition to this specification which

such cases.

2

may

well

be considered as a guide

to

IRC:83-2014

(Pt. IV)

and Cylindrical Bearings for use as temporary devices during construction, for example during launching of the super-structure, are also beyond the scope of this code. However, this specification may well be considered as a guide to these cases. Spherical

Bearings

2 DEFINITION 2.1

OF PRODUCT AND INTENDED USE

Definition of the Product

Spherical Bearing

The Spherical Bearing consists backing plates with a low

concave and convex steel spherical between thereby permitting rotation by

of a pair of matching

friction sliding interface in

shown in Fig. 1. For the purpose of providing the movement ability, the bearings may be combined with flat sliding elements, guides and restraining rings as shown in-curve sliding as

in

Fig. 2.

Fixed by sliding surface

Fig.

1

Spherical Bearing

c)

d)

-

Key any

a)

free for displacements

b)

internally

c)

externally guided for displacement

d)

fixed by a restraining ring Fig.

in

direction

guided for displacement

in

in

one one

direction direction

2 Spherical Bearings Combined with Flat Sliding Elements

3

IRC:83-2014

(Pt. IV)

Cylindrical Bearing

The

Cylindrical Bearing consists of a

a low

friction sliding

concave

surface to provide

friction

backing plate affixed with less sliding against the matching convex

cylindrical metal

in

from another plate as shown in Fig. 3. Cylindrical Bearings are also used combination with flat sliding elements and guides to form free or guided bearings as shown

in

Fig. 4.

cylindrical surface

a)

b)

Key a) b)

end stoppers and sliding surface without end stoppers for displacements in y fixed by

Fig.

direction

3 Cylindrical Beahngs

c)

Key free for displacements

b)

guided by an internal guide for displacements

c)

guided by external guides for displacements Fig.

2.2

any

a)

in

direction

4 Cylindrical Bearings Combined with

in

in

x direction

x direction

Flat Sliding

Elements

Intended Use

Spherical Bearings are suitable for

all

types of structures especially for long span and

continuous structures, Cable Stay and Suspension Bridges with relatively large and repetitive rotation

and

caused by variable loads, and for superstructures that bearings, e.g. in case of Road cum Railway Bridges.

translation requirements

induce fast sliding displacements

in

4

IRC:83-2014(Pt.

3

Terms and

3.1

IV)

TERMS OF REFERENCE AND SYMBOLS Definition

Base Plate Top and Bottom Steel Plates of the Bearing Assembly interfaced with the structure Concrete/Steel member.

Backing Plate Steel Plates confining the low friction sliding material like

PTFE/UHMWPE,

etc.

Guides Metallic projection from the

Top Plate getting locked with the adjacent

vice versa thereby restraining the

movement

of the Bearing

in

steel

component

or

the direction perpendicular to

that.

Mating Surface curved hard smooth surface of stainless

Flat or

against the

PTFE

steel, polished steel or

chrome

plated sliding

or other low friction sliding material.

Sliding Surface

PTFE

or

UHMWPE

low

thermoplastic material mounted on

friction

flat

or curved backing

plate providing low friction sliding to the mating surface.

Sliding Interface

Combination

of

Mating

and

Sliding

Surfaces

providing

relative

low

friction

sliding

displacement.

Approval Documents

The

e.g.

ETA,

FHWA or similar

documents acceptable under

code

be that from International reputed approving bodies having proven experience of research and Testing in the field of Structural Bearings and covering within the approval document all aspects incl. design, material, manufacturing, tolerances and acceptance. Isolated approvals or qualification of special approval

this

components separately that proposed to be used as approval document referred in this specification.

individual

treated 3.2

shall

inside the Bearing shall not

be

Notations and Symbols

The commonly used notations and symbols are defined here below. These notations and symbols uniquely or in combination used in the expressions in further clauses of this code are also defined at the places of their occurrence:

Notations

A

geometrical area of

flat

sliding surface or projected

area of the curved sliding

surface/specified cross sectional area of the bolt

a

effective

weld size

in

mm

(taking

in

account throat thickness)

5

IRC:83-2014(Pt.

IV)

minor side of the backing plate

Ap

compressed (un-deformed)

sliding surface

reduced contact area of the

A

= A.

sliding

under load

surface expressed

by the expression,

;^

r

b

distance

elevation)

(in

between the sliding surface and x-section under consideration

(refer Fig. 5)

b^

major side of the backing plate width of sliding surface

B

width of guide bar

0

distance

(in

plan)

between the

and the centre of the 0,

(PTFE/UHMWPE/others)

strip

interface resisting/transferring the horizontal force

sliding surface (refer Fig. 8)

clearance between secondary sliding surface (guides)

diameter of the backing plate Dj

internal dia of the restraining ring

e

eccentricity

short term static

modulus

of elasticity of concrete

modulus

of elasticity of concrete, for

Eg

modulus

of elasticity of steel

f

strength characteristic

i.e.

i.

permanent load

210000.00

5000 V

e.

effects

f^^

i.e.

0.5 E^

MPa

compressive strength of Sliding Surface

(PTFE/UHMWPE)

\^

specified min. tensile strength of the material

fy

specified min. yield strength of the material

h

projection of the flat/concave Sliding Surface

hf^

force lever

arm

for restraining ring in fixed bearing (refer Fig. 6)

h^

force lever

arm

for

h^^

depth of the restraining ring

k

reduction factor to reduce creep effects

L

diameter of the flat/projected diameter of the concave sliding surface

Lq

reference diameter = 300

L_.

length of rocker strip

Lg

length of Sliding surface strip

guide bars

in

.

above the recess

Guided Bearing

in

(refer Fig. 8)

sliding surface

mm (PTFE/UHMWPE/others)

length of guide bar

6

IRC:83-2014

n

number

N

vertical load

r

radius of curvature of the curved sliding surface

R^^

radius of curvature of the contact surface with the restraining ring

of bolts

radius of curvature of the rocker strip contact surface with the bottom t

thickness

t^

thickness of the backing plate

\.\

equivalent constant thickness for concave backing plate

t^^

thickness of the restraining ring

u

force free perimeter of

V

horizontal force

PTFE/UHMWPE

design value of anchorage total

(Pt. IV)

(bolt)

component

free to bulge

resistance

in

shear

resistance to sliding that including the anchorage strength and frictional

resistance

Suffixes

P

PTFE

U

UHMWPE

b

backing plate

d

design value of

movement

at Strength/Ultimate

k

design value of

movement

at Characteristic/fundamental/Service

sd

design value of load/force at Strength/Ultimate (ULS) condition

sk

design value of load/force at Characteristic/fundamental/Service (SLS) condition

X

longitudinal axis

y

transverse axis

xy

resultant

(Polytetrafluoroethylene) (Ultra

High Molecular Weight Polyethylene)

(ULS) condition (SLS) condition

Symbols a

design rotation

maximum

design rotation

in

ULS

(3

angle between the vertical and the resultant applied horizontal load

P„

Co-relation factor for Welds, to be taken as 0.9

6

half included

angle of the curved sliding surface

partial safety factor

7

IRC:83-2014

(Pt. IV)

partial safety factor for sliding

y^^ |j

co-efficient of friction

[i^^

co-efficient of friction for co-efficient of friction

secondary

sliding surface

between the bearing and substrate, 0.4

for steel

on

steel

and

0.6 for steel on concrete

a

pressure due to vertical load

maximum average X

coefficient

Az

maximum

used

to

contact stress permitted on the sliding surface

work out reduced contact Area, Ar

deviation of plane or curved sliding surface from theoretical surface

Abbreviations avg.

average

max.

maximum

min.

minimum

perm.

design permanent load/force

PTFE

Poly tetra fluoro ethylene

UHMWPE Ultra

High Molecular Weight Poly ethylene

ETA

European Technical Approval

FHWA

Federal Highway Administration

4 iVIATERIAL SPECIFICATION 4.1

Steel

components shall be rolled steel in accordance with IS:2062 Grade E350 min. or cast steel in accordance with IS: 1030 Grade 340-570W except for calotte which shall be only fine grain rolled steel conforming to !S:2062 Grade E 350 or above. Stainless Steel if used in special cases for the Bearing main components including backing plates for flat and curved sliding interfaces shall be in accordance with AISI 304 or Duplex Steel (UNS S32205) of ASTM A240. Equivalent or superior grades as per other national and international specification with proven performance and suitability to application requirements shall also be acceptable. Steel for Dowels etc. shall be rolled steel in accordance with IS:2062 Grade E250 B min. Steel for bearing main

4.2

The

Low

Friction Thermo-Plastic Sliding Material

(PTFE or

UHMWPE)

material shall be either pure polytetrafluoroethylene (PTFE), free sintered, without

regenerated materials and fillers or Ultra High Molecular Weight Polyethylene (UHMWPE) having high material strength and low frictional properties. The pattern of dimples shall be as 8

IRC:83-2014

described

Annexure-A

be recessed

shall

Use

in

"Properties of

Friction Sliding Material".

The

sliding surface

the metal backing plate compulsorily.

in

(UHMWPE)

of Modified sliding material

PTFE combined

Low

(Pt. IV)

with

having

frictional properties

enhanced load bearing capacity and

ability to

superior to that of

provide high velocity

can be considered for both Primary (flat or curved) interfaces. However, this shall be subject to the availability

displacement with longer service

life

and secondary (guides) sliding of approval documents from International approving bodies like ETA, FHWA or similar, acceptance by other Leading International Specifications, references of its usage in the Bearings application, satisfactory and proven test and performance records etc.

Reduction Factor,

4.3

(k) to

Reduce Creep

Effects

compressive strengths of PTFE/UHMWPE are given in Table 1 and valid for effective bearing temperatures upto 30°C for PTFE and 35°C for UHMWPE. For bearings exposed to a maximum effective bearing temperature in excess of above mentioned respective values, the aforementioned values shall be reduced by 2 percent per degree above 30°C/35°C in order to reduce creep effects of the PTFE/UHMWPE respectively.

The

characteristic

Table Material

Characteristic Compressive Strength

1

of Sliding Materials

Loading Condition

Application Condition

Main Bearing Surface

(f^)

f,

(MPa)

Permanent and Variable Loads

90

Variable Loads

90

Temperature, Shrinkage and Creep

30

Permanent Loads

10

PTFE Guides

Main Bearing Surface

UHMWPE Guides

Permanent and Variable Loads

180

Variable Loads

180

Permanent Loads, Effects of Temperature, Shrinkage

60

and Creep

CM1

Guides

Permanent and Variable Loads

200

CM2

Guides

Permanent and Variable Loads

120

Stainless Steel

4.4

accordance with AISI 31 6L or Ofir^^H\^J\Ao^ of IS:6911. The Stainless Steel sheet shall be attached to its backing plate either by bonding, counter screwing or by continuous fillet weld. Stainless

Steel

the

for

Sliding

Interface

shall

be

in

The thickness of the Stainless steel sheet shall be 1 .5 mm if attached by bonding, minimum 1.5 mm or above if attached by continuous fillet weld and min. 2.5 mm when affixed by counter screwing.

Surface roughness

accordance with

Care

shall

(Ry^.)

of the polished Stainless Steel sheet shall not

exceed

1

pm

in

EN ISO 4287

be taken

plate over the area

to

ensure that the Stainless steel sheet

which

will

be

in

is fully in

contact with the backing

contact with the sliding surface. To avoid the danger of air

9

IRC:83-2014

entrapment,

(Pt. IV)

releasing spots of

air

mm

max 10

length on two opposite sides

while attaching the stainless steel sheet to the backing plate by continuous

When

may be

provided

weld.

fillet

attaching the Stainless steel sheet by counter screwing, corrosion resistant fasteners

compatible with the Stainless steel sheet shall be used for securing its edges. They shall be provided at all corners and along the edges outside the area of contact with the sliding surface

maximum

with the

mm

spacing limited to 300

Intermediate and 50

mm at the edges.

Hard Chromium Plated Surfaces

4.5

curved surface of the convex steel plate mating with concave sliding surface shall be hard chromium plated. Hard chromium plating and the surface of its base shall be free from surface porosity, shrinkage cracks and inclusions. Small defects may be repaired e.g.

The

entire

by pinning

prior to hard

The thickness

chromium

of the hard

plating.

chromium

roughness of the plated surface

be

plating shall

shall not

exceed 3

at least

pm and

the

final

surface

|jm.

may be

Both the base material and hard chromium plating

100

polished to achieve the finish less

than the specified surface roughness. 4.6

iViateriai

Combinations

The permissible combination

and mating surfaces) to be used for The sliding surface shall be lubricated in

of the materials (sliding

be as given accordance with Clause 4.8. sliding interfaces shall

in

Table

Table 2 Permissible Combination of

2.

IVlaterials for

Permanent Applications as

Sliding Interfaces for Spherical Bearings

Guides

Curved Surface

Plane Surface

PTFE/UHIVIWPE

Stainless steel

PTFE/UHMWPE

Stainless

PTFE/UHMWPE

(dimpled)

Steel

(dimpled)

Hard chromium

plating

Aluminium Alloy*

Composite Material Stainless (CM1 and CM2)

Steel

aluminium alloy is permitted as mating surface for curved sliding interface only. The be AI-Mg6M or AI=Si7MgTF in accordance with the requirements of ISO 3522 or as covered in the special approval documents like ETA, FHWA or simillar.

Use

of

alloy shall

Composite Material

4.7

As an

alternative for strips

properties as per

4.8

in

guides, the composite material of type

Annexure-B can

having

also be used.

Lubricant

The Lubricant

shall

sliding material

and

be such that its

it

reduce the

frictional

18:14383

resistance and

wear

of the low friction

properties shall be retained through service range of temperature.

properties of the lubricant shall be as described listed in

CM1 and CM2

shall also

be referred.

10

in

Table

3.

The

For Silicon Grease, properties

IRC:83-2014(Pt.

IV)

Table 3 Physical and Chemical Properties of Lubricants Testing Standard

Properties

Worked

penetration

Dropping point Oil

Oxidation after

resistance

ISO 2137

26.5 to 29.5

ISO 2176

> 180°C

Annex G

Separation after 24 h at 100°C

Requirements

of

Eurocode EN 1337-2:2003

Pressure drop Annex H of Eurocode

EN 1337-2:2003

mm

< 3 percent (mass)

9 Deformations of Backing Plates

Fig.

The

°

Actual deformation of the backing plate

The maximum

relative

deformation "Aw,^^^"

the backing plate over the diameter

in

'L'

calculated from the following expression: 0.55 — —

Aw

=

1.1

+(1.7-0.85.d,/L).(2-d^/Lo)

T

.

k c .a c

.

k. b

.

a.

b

where, =

22

if

L 0 0.040.

mm, whichever

t^^

for

satisfy:

Va\+b\

greater,

is

where, is

the minor side of backing plate and

is

the major side of backing plate

Design Verification of Anchiorages Against Sliding Under Horizontal Force

5.7

Irrespective of the Bearing type (fixed or movable), the bearings shall

be adequately anchored

using Positive anchoring arrangement e.g. Bolts passing through Bearing

anchored

to

embedded welded

The

Dowels, Headed Stud connectors (Shear or Tension), Steel distribution plates the adjoining concrete structure or anchored to the intermediate steel plates

in

to the adjoining structure in

safety and

adequacy

horizontal force shall

described In

in

component and

case of

of the anchoring

be checked

Annexure-E

steel construction.

mechanism against sliding under the

at the ultimate limit state in

accordance with the stipulations

"Bearing Anchorage Design Rules".

the case of dynamically loaded structures

where extreme load

fluctuations

seismic zones (Zones IV and V), contribution due to

e.g. structures in high

application of

not be taken into consideration while designing the anchorages

i.e.

p^ shall

can occur,

friction shall

be taken as

zero.

Verification of the Stresses in the Adjoining

5.8

The to

Concrete Structure

strength of the concrete structure adjoining to the Bearings shall be checked so as

ensure safe bearing and transmitting the loads and forces that from the Bearings. The

concreting of the Bearing seating (Pedestal) and superstructure shall

may

be carefully done result in

failure.

The

described

in

to avoid the

undue deformation

stress

in

soffit

above the Bearing

voids/honeycombing underneath the Bearing which

components or even premature Bearing shall be checked against the expression

of the Bearing

the concrete structure

Annexure-F "Check

for

Permissible Stresses on the Adjacent Concrete

Structure".

6

6.1

MANUFACTURING

Dimensional Tolerance of Steel Components and Bearing Overall

The tolerances as

listed in

Table 5

shall

be applicable

components:

24

for the finished

Bearings and

its

1RC:83-2014 Table 5 Tolerance on Dimension of Steel

i)

Components and Bearing

Parameter

S. No.

Tolerance

Overall Plan Dimension a)

Machined

0 to + 5

mm or 0.5 percent of the drawing

dimension whichever b)

ii)

Un-machined (flange

is

higher

mm

or 1.0 percent of the 0 to + 10 drawing dimension, whichever is higher

portion)

0 to + 5

Overall Height

mm or

1

percent of the drawing

.0

dimension, which •ii)

(Pt. IV)

Parallelism of Bearing top surface

w.r.t.

bottom

1

in

±

1

is

higher

200

surface as datum iv)

Height of individual machined steel component

V)

Radius of Curvature steel

vi)

6.2

concave machined

0 to + 0.25

mm

convex machined

-0.25 too

mm

component

Radius of Curvature steel

for the

mm

for the

component

Curved Backing Plate a)

Dinnensiona! Limitation and Tolerance

The thickness

surface shall be 12

20

mm on

concave sliding and the space available on sides shall be min.

of the curved backing plate housing the

t^

mm

radius (refer Fig. 10)

If

^1

/ //

/ //

c Fig.

b)

f

10 Dimensional Limitations of Concave Backing Plate

Recess

in

the Backing Plate for Confinement of the Sliding Surface

The shoulders

of the recess shall

be sharp and square

to restrict the flow of

the sliding surface and the radius at the root of the recess shall not exceed 1

mm

(refer Fig. 11).

Dimensions

J' x-x Key 1

Sharp edge Fig. 11

Details of

Recess

25

for Sliding

Surface

in

millimeters

IRC:83-2014

(Pt. IV)

The

sliding surface shall ideally

maximum

permissible tolerance on the

exceed values specified

shall not

Table 6 Tolerance on

Fit

the recess without clearance.

in

fit

fit

501

6.

Gap (mm)

-

500

0.5

-

1000

1.0

1001

1500

-

Recess

of Sliding Surface in the

Dimension L (mm) 75

of sliding surface inside the recess

Table

in

The

1.5

where, projected diameter (refer Fig. 5)

L

'

. _

Flatness

c)

,

Surface of the curved backing plate to receive the concave sliding surface

such a way that the maximum deviation Az from theoretical plane surface shall not exceed 0.0003 d or 0.2 mm, whichever is

be finished

shall

in

greater.

Sliding Surface

6.3

The thickness

'tp'

of the sliding surface

corrosion protection shall

Thickness

't

'

in

p

Flat

mm

2.25 h =

Protrusion

'h' in

it's

protrusion

meet the conditions given

Table 7 Thickness

Design Values

and

.

'

't

in

and Protrusion

'h' in

Table

'h'

the unloaded condition with

7.

of the Sliding Surface

Guides

and Curved Sliding Surfaces

h

<

<

t

8.0; with

'h' in

mm

5.0 15

a > 15

i_ 10

±2

10±

L

2

Dimensions

•

Fig.

6.5

13 Examples of Recessed Sliding Surface Sheets

for

in

millimeters

Guides

Hard Chromium Surface

The hard chromium surface shall be visually inspected for cracks and pores. In addition to the visual inspection, the absence of defects shall be verified by any suitable non-destructive test e.g. Ferroxyl Test in accordance with Annexure-D "Ferroxyl Test for Hard Chromium Plating" of this specification. If any defects in the small portion are detected in the test, the hard chrome plating shall be reworked and the test shall be applied on the entire chrome plated surface and if the defects are still noticed, the hard chrome plating shall be rejected. Since hard chromium plating

can be damaged by provision shall be

air

made

is

in

acid solution or to fluorines

and

such as occur in industrial environment, special protect the surfaces in those conditions.

borne to

not resistant to chlorides particles,

27

IRC:83-2014

(Pt. IV)

Restraining Rings and Guides

6.6

component

be preferred as far as possible unless excessive dimension, cost of machining and material wastage etc. overrules the condition. In such cases option of welded Restraining Rings and Guides can be considered subject to fulfillment of the respective design requirements mentioned in this Restraining Ring and Guides monolithic with their parent

documents and the i)

ii)

following conditions:

be positioned and locked with its parent component by tongue and groove shaped machining/using the Allen-key bolts. Further, to achieve the desired strength to resist the horizontal forces, continuous welding (all sides) shall be done (refer Fig. 14).

The Ring/Guides

The weld

size

shall

and dimensions

and forces shear, bending, tension and

shall satisfy the acting loads

and checked against the applicable cases combined effects etc. i)

shall

viz.

case the acting horizontal forces is too high to with monolithic Ring or Guides shall be adopted. In

resist

by welding, option

TOP PLATE

ALLEN KEY BOLTS TONGUE AND GROOVE

WELD GUIDE BAR Fig.

14 Guide Bar Weld Connection with Top Plate (Typical)

Fasteners

6.7

Fasteners shall conform to their relevant IS/IRC Specifications.

Welding

6.8 All

welding shall conform to IS:816 and IS:9595 with electrodes of suitable grade as per

IS:814. Preheating

and post weld stress

reliving shall

be done as necessary.

The backing plate shall extend beyond the edge of Stainless Steel sheet the weld. TIG welding of Stainless Steel sheet is recommended.

accommodate

Protection Against Corrosion and Contamination

6.9

While doing the corrosion protection as specified Following care shall be taken:

Where

to

in

Clause 4.10

of this Specification.

the stainless steel sheet

is attached to it's backing plate by continuous fillet weld, the area of the backing plate covered by the stainless steel sheet need not be provided with the complete corrosion protection system. However, the area should be thoroughly cleaned and

carefully

agents

examined

prior to the

to

be free from dust, foreign

welding of the

SS

Sheet.

28

particles,

and sign

of rust or rust inducing

IRC:83-2014(Pt.

Where the the

full

stainless steel sheet

IV)

attached by screwing, counterpunched screwing or riveting corrosion protection system shall be applied to the backing plate behind the stainless is

steel sheet.

Provision against contamination of the sliding surface shall be

made by

suitable devices e.g.

Such

protection devices shall be easily removable for wiper seal, rubber apron or bellows. maintenance inspection purpose. replacement and/or All

other metallic components including Bolts, Fasteners and

Washers

etc. shall also

be

adequately protected against corrosion.

Assembly

6.10 Prior to

assembly the and

sliding surfaces shall

be cleaned.

assembly, the dimpled sliding surface shall be lubricated with lubricant according to Clause 4.8 in a way ensuring that all the dimples are filled without air

After cleaning

prior to

entrapment. For guides the sliding material shall be

amount

of lubricant into the surface

and wiping

off

initially

lubricated by rubbing a small

the remainder.

During assembly process, precautions shall be taken against contamination of lubricated surfaces.

The bearing may be provided

with a

movement

indicator scale which

face of the top sliding plate with a pointer pointing to

7

it

be fixed on the side from the Bearing bottom component. is

to

ACCEPTANCE, CERTIFICATION AND MARKING

Acceptance Testing, Certification and Marking shall be strictly adhered which forming the basis of Product conformance and acceptance for the Spherical and Cylindrical Bearings. Stipulations of this clause regarding the

7.1

Following

System will

a)

b)

of Attestation

form the basis of acceptance of the Spherical and Cylindrical Bearings:

Tasks of the manufacturer: 1)

Raw

2)

Factory production control/in-process testing

3)

In-house Test on Finished Bearing

Material Acceptance/Testing

Tasks of the accepting/inspection

authority:

inspection of factory and of factory production control

1 )

Initial

2)

Surprise/audit inspection on process of production and conformance test

3)

7.2

and Conformity

on raw materials and production in-process,

Witness of

final

if

deemed necessary

acceptance testing of finished product.

Lot Classification

For the purpose of Lot classification, following definitions shall be applicable •

A lot shall

comprise of the

total

number of Bearings manufactured

together, of

the type and load capacity as defined below, and offered for the Inspection at

29

IRC:83-2014(Pt.

IV)

a time to the Inspecting/Accepting Authority. However, the maximum number of Bearings in one lot shall be limited to 24. Bearings in excess of 24 Nos.

•

shall

be treated as separate

The

fixed

However,

and movable Bearings the movable bearings

movement

bi-directional

•

7.3

lot.

be

shall

irrespective

abilities shall

as separate

lots.

uni-directional

and

classified

of

be placed under the same

lot.

terms of Load capacity. Bearings with max. design vertical load less than 500 MT shall be considered as one lot and Bearings with more than 500 MT vertical load capacity shall be considered as separate lot. In

Manufacturer Internal Testing

Raw

and In-process Inspection to be carried out and documented for all Bearings and their Components. The Bearings thus manufactured shall be subjected to rigorous In-house Testing by the manufacturer prior to offering for the Acceptance Testing. Following In-house/internal testing on the finished Bearings shall be performed by the

Apart from the

material

Manufacturer: i)

Bearings shall be checked for surface

All

finish or

any other discernible

superficial defects. 11)

the

All

Bearings shall be checked for overall dimensions as per the

manufacturing tolerances specified

in this

code and the relevant contract

Specifications. iii)

At least 20 percent Bearings subject to a

04 and maximum of production quantity to be

minimum

of

20 numbers selected randomly out of the entire offered for acceptance shall be subjected to vertical the

maximum

design vertical load

and simultaneously the is

iv)

in

SLS

condition as

test load at 1.10 times

shown

in

the drawings

rotation of 0.02 radians or design rotation

whichever

higher.

From the entire production quantity to be offered for acceptance. One Bearing each selected at random shall be tested for Co-efficient of Friction at maximum design vertical load in SLS condition and Combined Vertical and Horizontal Load test (at 1.10 times the maximum SLS design loads), as the case applicable.

7.4

Acceptance Test by Inspecting Authority

Bearings passing the In-house Test requirements are then offered to the Accepting/Inspection Authority for Acceptance Testing. Following Acceptance tests authority shall

presence of the Inspection be performed on the components of the bearings or the bearing as a whole, in

as applicable. 7.4.1

Tests for conformance of raw materials 1)

In

initial

basis of

its

processing

Raw materials from the supplier/manufacturer acceptance. Random sampling and testing at

addition to the certificates of

forming the

and

30

IRC:83-2014

(Pt. IV)

Independent NABL accredited lab for the material used in the production of the Bearings like steel, sliding surface, stainless steel. Bolts etc. shall be done. The inspection/accepting authority at his discretion shall relax and not insist on conducting the above test subject to availability of the satisfactory test data for the similar test conducted on materials of bearings recently manufactured and supplied for other projects within a period of six months preceding the date of Testing.

7.4.2

components

ii)

Ultrasonic inspection of the steel

ill)

Test on welding

iv)

Test on hard chromium plating

v)

Surface

vi)

Thickness of the anti-corrosive treatment

Acceptance 1)

e. g.

Dye Penetration Test e. g.

finish of the stainless steel

test

Ferroxyl Test

sheet etc.

on finished bearings

Surface Finish Bearings shall be randomly checked for surface

finish or

any other discernible

superficial defects. ii)

Dimension Bearings shall be randomly checked Manufacturing tolerances specified

for overall

in this

dimensions as per the

code and the relevant contract

Specifications. iii)

Compression

One

(Vertical

Load) Test

Bearing selected at random from the

lot

under acceptance

simultaneously subjected to vertical test load of 1.10 times the

design vertical load

in

serviceability condition

rotation of 0.02 radians or design rotation,

\'ERTIC.AL

as shown

whichever

is

RAM

Typical Fig.

15 Vertical Load Test Set-up for Spherical Bearings

31

in

shall

be

maximum

the drawings and

higher. (Fig. 15)

IRC:83-2014(Pt.

iv)

IV)

Friction Test

For movable Bearings (Free Float and Slide Guide Types),

One

Bearing

random per lot shall be tested in order to determine the co-efficient of friction at maximum design Vertical Load in serviceability condition, the value of friction shall not exceed 0.03 under lubricated condition (Fig. 16). selected at

IN

TOP GLIDED BE.^JUNG C.\N ALSO EE

USED

.

Wim THE DIRECTiON OF \iOVE\EXT

P.AR.AILEL TO

THEDIEECnOXOF

APPLICATION OF HORIZONT.-a. FORCE

GUIDED SPHERICAL BEARING ORiENTED SUCH TH.AT THE GUIDES .ARE P.AR.ALLEL TO THE DIRECTION OF HORIZONTAL FORCE APPLICATION THUS AiLO\TOG SLIDING KORIZONT.U STOPPERS CAN -ALSO BE PROVIDED K BOTTOM PLATEN OF THE TEST RIG TO A'-'OID THE SLIPP.AGE OF THE BE.AR£\0 DLIRKG THE TESTING

Fig.

16 Coefficient of Friction Load Test Setup Details for Spherical Guided Bearing

v)

Combined

Vertical

and Horizontal Load Test

For Bearings required to resist Horizontal Forces (Fixed and Slide Guide Types),

One

combined

Bearing selected at random from each

lot

shall

be subjected

to

and Horizontal Load Test to 1.10 times of the respective maximum design loads and forces in serviceability condition (Fig. 17). Vertical

-K TO? GUIDED BEARING CAN ALS O BE L-SED ,

^TIH THE DIRECHON OF MOVEMENT ?AFJi.LLEL TO THE DffiECTiOK OF .APitlCAIDN OF HORIZONTAL FORCE

'

— HORIZONT.AL STOi^ERS CAN ALSO BE PROVIDED IN BOTTOM PLATEK OF THE TESTRIG TO AV OID THE SLS^AGE OF THE BEARING DURKG THE TESTING

Fig.

Notes

17

HOR

Load Test Setup Details

for Spherical

Guided Bearing

:

•

For tests specified under

and under

iii)

and

v) of

iii) and iv) of Clause 7.3 except for co-efficient of Friction test Clause 7.4.2, the Bearings shall be held under Load for a period

of 10 minutes.

32

IRC:83-2014 be done

SLS

(Pt. IV)

Loading.

•

All testing shall

•

Additional pre-fabricated taper plates inducing the desired rotation into the Bearing shall

•

In

be used

in

for

the Test assembly for the Vertical Load

test.

order to ensure that the Test Bearing having curved sliding surface do not topple, on top as shown in the test assembly figures shall be used

either the flat sliding surface

or else suitable supporting/clamping arrangement to hold the Bearing

assembly/testing shall be considered for

friction

and combined

in

place during

tests.

Acceptance Test on Finished Bearings as per Clauses 7.3 and 7.4 may be exempted for Bearings supplied with "CE Certification".

•

Observation

7.5

During the Testing, the inspecting/accepting authority shall examine the behavior of the

Bearings for any signs of Deformation or Crack on the Sliding surface and/or mating surface, Separation/Lift-off

between the

deformation or cracks

in

sliding

interface or seizure of the Bearing

Components,

weld. After the above tests are completed, the tested bearings shall

be removed from the test machine, dismantled and the components shall be examined for any signs of distress, permanent deformation in the components especially the sliding surface, warping, swelling, cracks or other permanent defects which may affect the serviceability or durability of the bearing.

The inspecting/acceptance

above

on finished Bearings shall also inspect the documents and reports submitted by the manufacturer about the internal factory production control e. raw material, in-process production and internal testing of finished product carried out by the manufacturer. authority apart from witnessing the

test

i.

Inspection Report

7.6

The

and inspection carried out both in house and in the presence of the Witnessing Authority shall be recorded in the standard testing formats alongwith their observations. These filled up formats alongwith the raw material test certificates, reports of the tests done inprocess e.g. welding (DPT), hard chromium plating (Ferroxyl Test), mating surface hardness test, ultrasonic test, S/S surface finish and Paint DPT etc. shall be compiled and submitted to the Inspecting/Acceptance Authority as Test Reports. 7.7

details of the tests

Certification

The approving/accepting manufactured

authority after getting satisfied with the Quality of the Product

shall issue Certificate of conformity of the product stating the conformity with

the provisions of this Specification

and clearance

to the

Manufacturer to effect the shipment

of the Bearings to the job site.

7.8 All

Marking Bearings shall have suitable identification plates permanently affixed which shall be visible

after installation, identifying the following information:

-

Name

of Manufacturer

33

lRC:83-2014(Pt.

-

IV)

Month and Last two

digits of the

year

in

which the Bearing IVIanufactured

(mm/yy)

Besides

-

Serial

-

Bearing Designation and Type

-

Design Performance parameters

Number

of the Bearing -

viz.

the Bearing Top Surface shall also be

this,

Load,

marked

Movement

etc.

with the following information to

facilitate their correct installation at site:

-

Centerline Marking

-

Bearing Designation and Type

-

Orientation Marking to facilitate correct placement on the Pedestal

-

Direction of Major

and Minor movement, as appropriate

-

Preset Marking,

applicable.

-

Location

8

The bearing Clause testing

7.8.

shall

Number upon each support

(If

required)

PACKAGING, TRANSPORT AND STORAGE

be labeled by the manufacturer with the marking requirement as stated

The marking

and acceptance

shall only

of several

transportation.

They

shall

fulfilled in all

components, which are not

temporarily clamped together at the place of manufacture. strong to hold the various bearing

in

be applied when the pre-requisites, regarding manufacturing,

accordance with Clauses 6 and 7 are

in

made up

Bearings being

if

components

in

respect.

rigidly fixed together, shall

Such clamps

shall

be

be

sufficiently

their correct positions during handling

and

be marked/painted with a clear distinguish colour from that of the

Bearing paint for easy identification. The Transportation Bracket shall be easily removable after installation or

designed

to

break once the bearing starts to function, without damaging

the bearing. All

Bearings that are too heavy to be handled manually shall have provision for the

lifting

devices.

Bearings shall be wrapped under heavy duty polythene sheets and secured on wooden pallets or inside shall then

be transported

The Bearings pallets

boxes strong enough

at the

Job

to the

Ventilation helps

component

in

and transportation. Bearings

Job Site under secured and horizontal condition.

Site shall

under covered space

to withstand the handling

be placed horizontally above the Ground Level on wooden

(well ventilated) to avoid spoilage

by

rain

water and dust

etc.

avoiding high humidity and condensation that could affect the Bearing

finishes.

34

IRC:83-2014

9

ASPECTS RELATED TO BEARING PERFORMANCE AND INSTALLATION

order to ensure bearing alignment and placement

In

(Pt. IV)

and Specifications, a reference index marking and Top Component. The following

shall

in

accordance with the contract plan

be provided on the Bearings Bottom

Deviation shall be

limits of

maximum

permissible

the

in

Installation of the Bearings:

Level of Seating

:

mm

± 3

max. from actual

(maximum exceed 3 In

Plan Deviation

/

:

Alignment of Sliding Surface

Parallelism of Bearing

Component 9.1

w.r.t.

to

± 3

mm

level difference

under the same

installed

Top

drawings

between any two Bearings

line of

support shall also not

mm)

max.

in

either direction.

0.3 percent of Bearing

:

level specified in the

direction of

movement

0.1 percent

Slope max.

Slide

Plate Dimension

the

in

bottom

Installation

Bearings are to be installed with due care with the design of the Structure.

ensure

to

The primary

their correct functioning in

accordance

factors to be considered during the Installation

of the Bearings are:

Design Based Aspects •

Provision of the Bearings

the structure shall be so

in

the least chances of dust and

water seepage that •

Provision

for

accommodate

may

Jacking

dirt

made so as

to

have

accumulation and also spoilage from

affect their

rain

performance.

and adequate space and clearances

Points

the jacking arrangements shall be

made

to

during the

design/construction of the Structure to allow repair, replacement of bearings, if

•

required during service.

Consultation with the Bearing manufacture shall be done at an early stage of the Bridge design to avoid the hassles of Pre- Stressing Tendons and anchor

blocks fouling with the Bearing Dowels.

Transportation and Site Handling Aspects •

Transport Brackets are not to be relied upon for the

•

On

Lifting of

receipt of the Bearings at Site, the Contractor shall

Examination of the Bearings

to

35

the Bearings.

have a

visual

ensure that no damage or displacement

IRC:83-2014(Pt.

IV)

of the Bearing

components re-assembly

rectification or

taken place during the transportation. Any

is

if

done

required shall be

strictly in

the presence

of the Manufacturer's Representative.

installation

•

Aspects Bearings shall be installed

truly horizontal with

of the Bearings perfectly parallel to

•

each

Top and Bottom Components

other, unless otherwise stated.

embedded as per the Shop

For pre-cast construction, the positioning of the Bolts and Dowels in

the Sub-structure/Superstructure shall be

made

strictly

Drawings. •

The

Dowels/Distribution Plates shall be properly grouted with suitable grout

material ensuring no voids,

honeycombing underneath and above the Bearing

bottom and top plates respectively.

In

case

of

Movable Bearings,

particular

care shall be taken to ensure the correct orientation of the Bearings. •

For

In-situ

type of Construction the Bearings shall be covered from

to avoid the ingress of

•

In

cement

slurry etc. inside the Bearing

case of Pre-cast Construction, extreme care

loading

is

to

temporary support as

pendulum

to avoid

impact

this

may cause

i.e

without any additional

the overturning of the Girders due to

Transport brackets shall be removed at an appropriate time after the casting

diaphragm and

Bearings and

its

once the process

setting of the Superstructure Concrete.

components

Slurry Deposit etc.

9.2

Components.

effect.

of the cross

•

sides

onto the Bearings while launching the Girders/Superstructure.

Girders shall not be rested freely over the Bearings

•

be taken

ail

shall

be checked

and the surrounding area

of Bearing installation

is

for

any

shall

dust, dirt or

Cement

be cleaned thoroughly

finished.

iVIaintenance

Bearings shall be designed and manufactured that the undesirable effects

to

make them

virtually

maintenance free so

caused by extreme atmosphere or aggressive environmental

condition/unforeseen events can be eliminated to a great extent. However, the surrounding

area of the Bearings shall always be kept clean and dry to avoid Provisions for suitable easy access to the Bearing shall be for the

made

damage in

to the Bearings.

the construction drawings

purpose of inspection and maintenance.

Inspection of Bearing at site

is

required to be carried out from time to time to ascertain the

performance of the Bearings. Periodic nominal maintenance of Bearing

36

shall

be carried out

in

IRC:83-2014 order to ensure better performance and longer

life

of the Bearings.

The Bearings are

required to be inspected at an interval of approx. one year for the interval of

two years thereafter or as agreed between the

the Bearings shall also be

examined

and the

in

generally

years and at an

contractor.

carefully after unusual occurrences, like

earthquakes, cyclones and battering from debris

The

client

five

first

(Pt. IV)

However,

heavy

traffic,

high floods.

inspection shall be preceded by careful cleaning of the Bearings as well as

its

space, depending on the actual conditions around the Bearings, e.g. deposit of

surrounding salt,

debris,

dust or other foreign material.

Elements of Inspection

The

following are

necessary

to 1)

recommended

inspection elements and actions which are considered

monitor and upkeep the Bearings:

Measurement of Movement: During required to be taken and

documented

inspection at to

compute

measurements are movement and rotation

site,

its

values in relation to their design values to ascertain whether the performance of the Bearings

is

To ascertain

satisfactory.

maximum movement, measurement

should be taken once during peak winter (early morning) and once during

peak summer (afternoon) and corresponding atmospheric temperature should be recorded. The recorded value of

movement

shall

be compared

with the design values. 2)

Measurement required to be

of Dimensions: Overall dimensions of the Bearings are

measured and compared

with the actual dimensions to

ascertain any excessive stress or strain on the Bearing. 3)

Evidence of locked Bearing

is

measures 4)

in

found to be shall

in

Condition:

locked

-

If

any movable or

in/jammed condition, necessary

rectification

be taken immediately.

Evidence of Corrosion:

If

surface of the Bearing

detected, the following

In

rotating part of a

addition, the root

is

cause

corrosion of any part of exterior exposed steel

of

measures may be taken. defect should be analyzed and proper actions

should be taken to avoid recurrence of the problem.

5)

•

Detect affected

•

Wire brush the affected portion

•

Apply protective coating as per Manufacturer's Specifications.

part.

to clean of

it's

rust.

Condition of the adjacent Bridge Structure: The condition of the structure adjacent to the Bearings

any damage and necessary actions immediately.

37

is

also required to be inspected for

to repair the

same, should be taken

IRC:83-2014(Pt.

IV)

Results and Actions

The

result of

every inspection has to be recorded

in

the inspection report and shall be deeply

discussed with the project Consultants and the Bearing Manufacturer and classified different categories

depending upon the action required

to

be taken

in

like:

1)

Re-inspection and/or monitoring

2)

Further measurements/long-term monitoring or design analysis needed (e.g.

considering

is

required.

extreme temperatures/exposures,

variation

of

loads,

etc.).

3)

4) In

,

Minor repair works

e.g. cleaning, repainting, etc.

Repair or replacement of entire Bearings or parts of the Bearings.

case of defects where the cause

of

necessary actions cannot be determined by the

inspecting person or the responsible Bridge Engineer, the bearing manufacturer shall be

consulted.

38

.

lRC:83-2014(Pt.

!V)

Annexure-A (Refer Clause 4.2)

Properties

A.O

of

Low

Thermo-plastic Sliding

Friction

IVIaterial

(PTFE or

UHlViWPE) Pattern of Dimples

A.1 Fully

molded sheets with

cavities or dimples for lubrication shall

be used

for flat/curved sliding

The dimples shall be formed by hot pressing or molding and strictly not by machining or drilling. Where dimples are produced by hot pressing, the temperature during the pressing process shall not exceed 200°C for PTFE and 80 percent of the melting temperature in case of UHlViWPE. The pattern of dimples shall be as shown in Fig. A.1 surfaces.

Dimension

"

in

Millimeters

Key 1

Main direction of Fig. A.1

Note

sliding

Pattern of Dimples

in

Recessed

PTFE/UHMWPE

Sheet

:

UHMWPE

annexure and elsewhere in this code are the gist only and merely to serve as a information guide to the Design and Accepting Authorities about the availability of such materials as an option.

The

information for

as given

in

this

The manufacture and use of UHMWPE material inside the Bearings may be governed by Patent Control Rights. The responsibility of acquiring such materials legally for use in the Bearing applications and

if

required, proving the license rights to use such materials within

the offered product shall be solely of the supplier/manufacturer of Bearings. For detailed information, specific approval

bodies

like

ETA,

document

FHWA, CALTRANS

for the material issued

or similar shall be referred.

39

from International approving

IRC:83-2014

(Pt. IV)

Annexure-B (Refer Clause

B.O

Properties of Composite

B.1

Composite

This

is

In

IVIaterials for

Secondary Sliding Surfaces

l\/laterial CIVI1

a composite material consisting of three layers; a bronze backing strip and a sintered

interlocking

The

4. 7)

porous matrix, impregnated and overlaid with a PTFE/lead mixture.

material shall conform to the characteristics listed

addition, the condition of the material

and

its

in

Table B.1.

surface finish shall be checked visually.

Table 8.1 Characteristics of

Bronze backing

CuSn 6 composition by mass

CM1

material:

P

<

0.35

Pb

<

0.10

Fe

<

0.10

% % % %

n KJ

^sn \J\J

/o

0 30

%/u

Sn

\

5 to 7.50

7n +

<

Mi

<

nthpr