irc.gov.in.sp.066.2005

IRC:SP:66-2005

GUIDELINES FOR DESIGN

OF CONTINUOUS BRIDGES

INDIAN ROADS CONGRESS 2005

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IRC:SP: 66-2005

GUIDELINES FOR DESIGN

OF CONTINUOUS BRIDGES

Published by

THE INDIAN ROADS CONGRESS Jamnagar House, Shahjahan Road, New Delhi- 11 00 11 Price

Price Rs. 160/(Plus Packing

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)

^^^age)

IRC:SP:66-2005

First

Published

Reprinted

2005

:

July,

:

August, 2008

(The Rights of Publication and Translation are reserved)

(The

official

in

its

amendments

to this

document would be published by the IRC

periodical, 'Indian Highways',

effective

which

shall

be considered as

and as part of the code/guidelines/manual, Date specified therein)

Printed at Options Printofast, Delhi- 11 0092

(500 copies)

etc.

from the

IRC:SP:66-2005

CONTENTS Page Personnel of the Bridges Specifications and Standards Committee

(i)&(ii)

1.

Introduction

1

2.

Scope

1

3.

Definitions

2

4.

Impact Factor

2

5.

Continuous Bridges

6.

Bridges

7.

References

made Continuous Through Deck Slab

.2 5

7

IRC:SP:66-2005

PERSONNEL OF THE BRIDGES SPECIFICATIONS AND STANDARDS COMMITTEE (As on 20-12-2004) 1.

2.

Addl. Director General, Ministry of Shipping,

V.K. Sinha

Chief Engineer, Ministry of Shipping, Road Transport and

(

3.

Road Transport

Velayutham ( Convenor)

V.

&

Co-Convenor)

Chief Engineer (B)

Highways,

Highway,

S&R

New

New

Delhi

Delhi

Ministry of Shipping,

Road Transport & Highways, New Delhi

(Member-Secretary) (A.N. Dhodapkar)

Members 4.

K.N. Agrawal

5.

S.

6.

C.R. Ahmchandani

Ahmed

C-33, Chandra Nagar, Ghaziabad-201 Oil

PWD, Shillong STUP Consultants

Secretary to the Govt, of Meghalaya

Chairman

&

Managing

Director,

Ltd.,

Mumbai 7.

A.K. Banerjee

B-210, (SF), Chitranjan Park,

New Delhi

8.

Ashok Basa

Director (Tech.) B. Engineers

& Builders Ltd., Bhubaneswar

9.

P.C. Bhasin

ADG (B), MOST (Retd.) 324, Mandakini Enclave, New Delhi

10.

S.S.

Chakraborty

Managing

New

Director, Consulting Engg. Services

(I)

Pvt. Ltd.,

Delhi

11.

K.K. Gupta

House No. 1149, Sector

12.

A.R. Jambekar

Chief Engineer

&

Faridabad

19,

General Manager (Tech.)

CIDCO, NAVl

Mumbai 13.

S.K. Jain

Director

& Head, Civil Engg. Department, Bureau of Indian

Standards, 14.

S.K. Kaushik

Delhi

Chairman, Estate IIT,

Kand

New

&

Works

&

Coordinator

(TIFAC-CORE)

Roorkee

Consultant, Bhopal

15.

C.V.

16.

Ninan Koshi

17.

Prafulla

18.

RY. Manjure

Director, Freyssinet Prestressed Concrete Co. Ltd.,

19.

N.V. Merani

Principal Secy., Maharashtra

20.

M.K. Mukherjee

40/182, Chitranjan Park,

21.

A.D. Narain

Director General (Road Dev.)

Kumar

DG

(RD) & Addl. Green, Gurgaon

DG (RD) &

AS,

Secy.,

MORT&H

S.K. Puri

(Retd.),

H-54, Residency

(Retd.) D-86, Sector-56,

Noida

Mumbai

PWD (Retd.), Mumbai

New Delhi

(Retd.) B-186, Sector-26, 22.

MOST

&

Addl. Secretary,

MOST

NOIDA

Chief Engineer, Ministry of Shipping, Road Transport and

Highways 23.

N. Rajagopalan

Chief Technical Advisor, L&T-Ramboll Consulting Engg. Ltd.,

Chennai 24.

M.V.B. Rao

A- 181,

Sarita Vihar,

(i)

New Delhi

IRC:SP:66-2005

Subba Rao

Chairman, Construma Consultancy (P)

Mumbai

25.

Dr. T.N.

26.

S.A. Reddi

Dy. Managing Director,

27.

Director

Highway Research

28.

G. Sharan

Member (T), National Highways Authority of India, New Delhi

29

N.K. Sinha

DG

(RD)

&

SS,

Chitranjan Park,

M.G. Tamhankar

Dr.

31

Mahesh Tandon

Managing

RB. Vijay

A-39/B,

Chief Engineer (NH)

(Shri S.K.

32. 33.

Planning

Chennai

MORT&H

(Retd.) G-1365,

Director,

Tandon Consultants

Floor,

Mumbai

(P) Ltd.,

New Delhi

DDA Flats, Munirka, New Delhi De)

M.P PWD, Bhopal

& Budget

34.

Addl. Director General

HQ DGBR,

35.

Chief Engineer (NH)

U.P PWD, Lucknow

36.

Chief Engineer (NH)

Chepauk, Chennai

37.

R. Subramanian

Engineer-in-Chief,

38.

Rep. of

RDSO

PWD, New

Delhi

(B&S) Bidges

Members

Momin), Secretary

Maharashtra

39.

President,

40.

Director General

(Indu Prakash), Ministry of Shipping,

(Road Development)

Highways,

Secretary,

IRC

(S.S.

& Structures

RDSO, Lucknow

Ex-Ojficio

IRC

Seema Sadak Bhavan, New Delhi

(R.K. Gupta) Executive Director Directt.,

41.

Ground

Delhi

BH-1/44, Kendriya Vihar Kharghar, Navi

30. .

Gammon India Ltd., Mumbai

Station,

New

Ltd.,

New

(R),

PWD, Mumbai

Road Transport &

Delhi

(R.S. Sharma), Indian

Roads Congress,

Sector-6, R.K. Puram,

New

Kama

Koti Marg,

Delhi

Corresponding Members

PWD (Retd.), Panchkula

1.

M.K. Agarwal

Engineer-in-Chief, Haryana

2.

M.K. Bhagwagar

Executive Director, Engg. Consultant Pvt. Ltd.,

3.

A. Chakraborti

Addl. Director General (TD),

4.

Dr. V.K. Raina

B- 13, Sector- 14, Noida

(ii)

CPWD, New

New

Delhi

Delhi

IRC:SP:66-2005

GUIDELINES FOR DESIGN OF CONTINUOUS BRIDGES

INTRODUCTION

1.

At

1.2.

its first

Committee

The Reinforced, Prestressed and Composite

1.1.

meeting on 29* April, 2003, the

felt that in

construction

the light of the massive

programme

executionin the highway sector,

Congress was reconstituted

to bring out

in

2003 with the

was under was necessary

that

Concrete Committee (B-6) of the Indian Roads

it

guideUnes on certain topics which were

not adequately covered in the existing

following personnel:

IRC Codes

and Standards. The design and construction of continuous bridges was one of the topics selected.

NinanKoshi Addl. T.

Viswanathan

was decided

Convenor Co-Convenor

It

... ...

Member-Secretary

the guidelines

...

DGBR

that while highlighting the special

design and detailing requirements in each case,

would be generally in Line with IRC: 1

and IRC:21 with additional inputs from BS:5400,

EURO

Members Alok Bhowmick A.N. Dhodapkar Vinay Gupta

wherever

of the guidelines was

meetings and finalized in

its

its

several

meeting held on

3"^

September, 2004. The draft document was approved by Bridges Specifications and Standards Committee in its meeting held on 20* December,

S.D. Limaye M.K. Mukerjee Dr. A.K. Mulhck

2004. The document was considered by IRC Council in its 173"^ meeting held on 8* January,

Rajagopalam

2005

G.R Saha R.S. Sharma Dr.

in Bangalore

modifications.

and approved subject to certain

The required modifications were

accordingly carried out by the Convenor, B-6

N.K. Sinha

Committee before sending the doucument

K.B. Thandavan

S&R,

for

pubUcation.

MOSRT&H

Ex-Ojficio

2.

Members

IRC Momin)

President,

(RD)

initial draft

discussed by the B-6 Committee at

Jose Kurian

DG

codes,

prepared by Shri Alok Bhowmick. The draft was

S.G. Joglekar

(S.S.

The

1.3.

G.R. Haridas

C.E. (B)

AASHTO

necessary.

A.K. Banerjee

Dr. N.

and

SCOPE The

guidelines cover the analysis and design

requirements for the following types of concrete

MOSRT&H

bridges

(Indu Prakash) Secretary, (R.S.

IRC

a) Continuous Bridges

Sharma)

b) Bridges

made continuous through deck

slabs.

Corresponding Members

Ashok Basa C.V. Kand

The guidelines

are applicable for the design

of continuous type of bridges in reinforced concrete

1

IRC:SP:66-2005 or in prestressed concrete or precast girder bridges loads

made

&

fully continuous for

live load

diaphragm

at

by providing

account

all

aspects of response of the structure to

loads and imposed deformations.

superimposed

in-situ concrete

support or bridges with tied deck

5.1.2.

The

effects of creep

and shrinkage of

slabs with continuity provided using dowel bars

concrete, temperature difference and differential

debonded from girder

settlements need not be considered while checking

at

support.

It

shall

be read

in conjunction with the existing provisions in the

relevant

the safety against ultimate stage failure*"

5.1.3.

DEFINITIONS

3.

.

IRC Codes. Secondary effects due

to hyperstatic

reactions of prestress shall be taken into account

while analyzing the structure. For ultimate stage 3.1.

Continuous Bridges

checks, the load factor for prestress (including the hyperstatic effects) shall be taken as 1.0

Continuous bridge

is

a bridge with the

superstructure longitudinally continuous over

methods of achieving the continuity in Superstructure. Fig.l shows some of such several

methods.

,.

Due account

shall

be taken of the change

in nature of the structural

system and in material

5.1.4.

intermediate supports on bearings. There are

properties that occur during the construction

sequence of a continuous bridge. The behaviour

.

at

any stage of the construction sequence

shall

be

analyzed, duly taking into account the effect of 3.2.

Bridges

made Continuous through

creep redistribution.

Deck Slab 5.1.5.

These are bridges are simply supported, cast-in-situ

deck

built using girders,

which

critical section for

shear shall be as

follows

and made continuous through

slab. (i)

When

the reaction in the direction of the

applied shear introduces compression into the

IMPACT FACTOR

4.

The

end region of the member, sections located a distance less than

For continuous bridges, the

live load

impact

support

factor shall be calculated in accordance with

may be

'd'

at

from the face of the

designed for the same shear

as that

computed

When

the reaction in the direction of the

at

distance

'd'.

Clause 211 of IRC:6-2000, wherein the span length to

be considered shall be as under

:

(ii)

applied shear introduces tension into the end (i)

For bridges with spans of equal effective

region of the member, shears computed

length, the effective span length (c/c of pier).

face of the support shall be used in the design

of the (ii)

5.2.

For bridges with only deck continuity, the effective span

5.

member

at that section.

For bridges with spans of unequal effective length, the least effective span length.

(iii)

at the

on which the load

is

Design

The design bending moment over an

placed.

intermediate support of a continuous deck supported on bearings

CONTINUOUS BRIDGES

may be

equation'^'

5.1. Analysis

Mj = (M - qaV8)

or 0.9M, whichever

where, 5.1.1. Elastic

method of analysis

shall

calculated by

be used to

M, = Design bending moment.

determine the forces and deformations, taking into

2

is greater,

IRC:SP:66-2005

Stifch

nrcox

pour^^^^ r^°"*''®^^'' constructed

I

'^^

llUiaJJ-U-

lt3

a)

^

Bridge

a

ItJ

Balanced Cantilever Construction Technique (Cast-in-place or Precast segmental)

c) Incremental

Launching Method b)

Span by Span Method

pCost

in [situ

Slab and D|iophragm

-Precast Girder

-mm

d) Precast Girders

asT

w

Made continuous by

vsmr

in situ

slab

& Diaphragm

(ForSIDL&LL) Fig.

1

.

Methods of Achieving

3

continuity in Bridge

Deck

IRC:SP:66-2005

M

= Analysed Bending moment at centerline of intermediate support.

R

= Reaction

a

= Width of Bearing

= R/a

q

(Refer Fig.

Fig. 2.

5.3.

Dimensioning

&

Detailing

Bearing Layout

&

a)

layout in a continuous structure

2).

The layout of cover

is

for straight continuous

curved continuous structures

in Figs. 3,4

an important

-

Fig.

4

& 5 respectively.

The arrangement shown

which shall be estabhshed during the initial

in the Fig. 3,

4 and 5

are only indicative and any other layout

design process itself. The layout of the bearings shall

in the direction of span

and skewed continuous structures are shwon

Movements: The

selection of the bearing type and the bearing

task,

intermediate support

Design Bending Moment over an Intermediate Support

girders,

5.3.1.

at the

/

arrangement of bearings can also be adopted.

correspond to the structural analysis of the

Methods of

analysis, shall take into account the

whole structure. The expected bearing movements and rotations shall be determined

bearing orientations to determine the bearing

taking into account the sequence of construction.

to the substructure.

In case of stage

by stage construction,

movements and corresponding

stability

5.3.2.

of the partially completed unit shall be ensured

by

suitable

means, which

shall

The

forces transferred

horizontal earthquake forces that are

being transferred through the fixed bearing in a

be clearly spelt

continuous bridge

is

usually large. There

is

a

out by the designer in the working drawings.

concentration of stress

Some of the typical layout of bearings for various

back reinforcement may be necessary

forms of continuous structures are as shown in

junction of fixed bearing with deck. Additional

Figs. 3,

4 and

reinforcement

5.

4

may be

at the joint and suitable

tie

at the

required to be provided

IRC:SP:66-2005 Span Length,

Span Length, L2

LI

4

4

4

^

4^

^ ^^

-$

4

^

^

-

—

^4-

>

-

Free Bearing

(V)

Fixed bearing

Guided Bearing

Fig. 3. Typical Bearing Layouts for Straight

Continuous Bridges

within the influence width, in concrete adjoining the fixed bearing,

which

the horizontal force that

shall is

6.

be designed to resist

MADE CONTINUOUS THROUGH DECK SLAB BRIDGES

transferred through the

For bridges made continuous through deck

bearings. These reinforcements shall be of length sufficient to ensure proper transfer of force.

Fig.

slab,

6 shows a typical detail of such reinforcement.

two generic type of connections normally

adopted for different situations are as described below:

5.3.3.

When

couplers are used for extending

prestressing cables, not

Type

more than 50 per cent of

1:

Continuous separated deck slab

in

the longitudinal post tensioning tendons shall be

which the deck

coupled

over the intermediate piers, without continuing the

at

any one section

5

slab

is

continued monolithically

lRC:SP:66-2005

^^^^

^

Free Beoring Fixed Bearing

Guided Bearing Pin

° I

beoring

j

Fig. 4. Typical Bearing

Layouts for Curved

Continuous Bridges

6

IRC:SP:66-2005 The length of

girders.

considered as simply supported for the design of girders. Hence specific clauses pertaining to

the separated deck slab

between the girders shall be sufficient to provide both short-term and long-term flexibility required to accommodate rotation of the girders.*^* (Fig. 7a

continuous structure do not apply for these bridges. For lateral loads however, the bridge is be treated as continuous. The continuity slab over pier shall be designed for the forces arising

& Fig. 7b).

to

This type of connection

is

and construction. However

moment continuity

it

out of the effect of such continuity, duly taking into account the effect of rotation of the girders

simple in design

does not provide

subsequent to casting of the continuity

at the supports.

slab.

For

the purpose of design of continuity slab, the

is

permissible reduction in allowable stress in reinforcement shall be considered as 80 per cent

which the deck slab hinged over the pier using partly debonded

Type 2

:

Tied deck slab

doweUing

in

to

(Fig. 8).

This type of detailing

medium span

is

lengths and

applicable for short to

In case of bridges with deck continuity, the

minimising

detailing of crash barrier for the continuity slab

is

aimed

at

portion shall be done carefully.

the number of expansion joints and improving riding

shall

be

left

allow for flexing of the slab.

rotational capacity, with a sealed notch provided in the

Gaps

in crash barrier at the ends of continuity slab to

the tied deck joint retains the

However

quality.

account for fatigue.

deck surfacing. 7.

should be noted that bridges made continuous through deck slab do not provide

REFERENCE

It

moment continuity and thus in terms

In this publication, reference to the following

and Japan Road Association Standards has been made. At the time of

IRC,

of structural

action for vertical loads, the bridge can be a

BS,AASHTO

or BEARING/

||NT£RMEDIATE SUPPORT Precc3st 1-

r -\

— a)

;

q.

OF TREE BEARING

q_

OF FIXED BEARING

beam

Precast

-q. OF FREE BEARING

At Intermediate Support

a)

With wide gap between supports over Pier

:

^ Q_

beam

of

pier

OF BEARING/ END SUPPORT Precast

-1—1-,|

Q.

beam

-

Precast

beam

OF FREE BEARING

Separated decl< Compresible

tiller

Slob ond Precost

in

slob lengtti between

Cost

in

situ

Slab

Beam

(6mm mimimum) —(i OF FIXED BEARING Precast

Precast

Beam

4

b)

:

OF FREE BEARING

At End Support r[d= ANCHORAGE LENGTH OF BAR

b)

A I INFLUENCE WIDTH

Fig. 6.

Beam

Cast in situ Diaptiragm

REINFORCEMENT

Arrangement of Tie Back Reinforcement

Fig. 7.

at

:

With narrow gap between supports over Pier

Connection Type

1

:

Continuous separated

Deck Slab

Fixed Bearing

7

IRC:SP:66-2005

of

Precast

pier

beam

Precast

beam

1^

4' 1

1

F

N

Crack-induceX filled

with

slot in surfacing rubD«r/bitunnen seal

Higti

yield

strength

dowel bor with suitable protective coating

Detail

Fig. 8.

publication,

ttie

editions indicated

were

-

X

Connection Type 2 Tied Deck Slab :

valid. All

&

7.1

Codes

1.

IRC:6-2000 Standard Specifications and Code of Practice for Road Bridges, Section II-

Specifications

standards are subject to revision and the parties to

agreements based on these guidelines are

encouraged to investigate the possibility of applying the

Loads and Stresses (Fourth Revision)

most recent editions of Standards.

8

IRC:SP:66-2005

2.

IRC: 1 8-2000 Design Criteria for Prestressed

6.

Concrete Road Bridges (Post Tensioned

Japan Road Specification for Association

Highway Bridges

Concrete) (Third Revision) 7.2. 3.

IRC:2 1-2000 Standard Specifications and Code of Practice for Road Bridges Section III Cement Concrete (Plain and Reinforced)

1

.

BS

5400:Part

4:

&

Publications

Brain Pitchard 'Bridge Design for

Economy

be Durability-Concept for New, Strengthened

and Replacement of Bridges.

(Third Revision) 4.

Papers

Code of

Practice for 1984

Design of Concrete Bridges

2.

Gunter Ramberger 'Structural Bearings and

Expansion Joints for Bridges' SE6 5.

AASHTO

LRFD

Bridge

Design

Zurich.

Specifications: 1999 Interim

9

lABSE

(The official amendments to this document would be published by the IRC in

its

periodical, 'Indian Highways'

effective

,

which shall be considered as

and as part of the code/guidehnes/manual, etc. from the Date specified therein)