IS 13920 : 1993

(Reaffirmed 2003)

Indian Standard

DUCTILE DETAILING OF REINFORCED

CONCRETE STRUCTURES SUBJECTED TO
SEISMIC FORCES -CODE OF PRACTICE
(Third Reprint NOVEMBER

UDC

1996)

69*059*25 ( 026 ) : 624-042-7

@J BIS 1993

BUREAU
MANAK

November 1993

OF

BHAVAN,

INDIAN
9

BAHADUR

NEW

DELHJ

STANDARDS
SHAH
llOOO2

ZAFAR

MARO
.
Price Group 7

Earthquake

Engineering

Sectional

Committee,

CED 39

FOREWORD
This Indian Standard was adopted by the Bureau of Indian Standards, after the draft finalized by
the Earthquake
Engineering
Sectional Committee
had been approved by the Civil Engineering
Division Council.
IS 4326 : 1976 Code of practice for earthquake
resistant design and construction
of buildings
while covering certain special features for the design and construction
of earthquake resistant
buildings included some details for achieving ductility in reinforced
concrete
buildings.
With a
view to keep abreast of the rapid developments and extensive research that has been carried out
in the field of earthquake
resistant design of reinforced
concrete
structures,
the technical
committee
decided to cover provisions for the earthquake
resistant design and detailing of
reinforced concrete structures separately.
This code incorporates
a number of important provisions hitherto not covered in IS 4326 : 1976.
The major thrust in the formulation of this standard is one of the following lines:
a) As a result of the experience gained from the performance,
in recent earthquakes, of
reinforced concrete structures that were designed and detailed as per IS 4326 : 1976, many
deficiencies thus identified have been corrected in this code.
h) Provisions on detailing of beams and columns have been revised with an aim of providing
them with adequate toughness and ductility so as to make them capable of undergoing
extensive inelastic deformations and dissipating seismic energy in a stable manner.
c) Specifications on a seismic design and detailing of reinforced concrete shear walls have been
included.
The other significant changes incorporated in this code are as follows:
a) Material specifications are indicated for lateral force resisting elements of frames.
Provisions
b) Geometric constraints are imposed on the cross section for tlexural members.
on minimum and maximum reinforcement
have been revised.
The requirements
for
detailing of longitudinal
reinforcement
in beams at joint faces, splices, and anchorage
Provision are also included for calculation of design
requirements are made more explicit.
shear force and for detailing of transverse reinforcement
in beams.
c) For members subjected to axial load and flexure, the dimensional
constraints
have been
imposed on the cross section.
Provisions are included for detailing of lap splices and for
A comprehensive set of requirements is included on
the calculation of design shear force.
the provision of special confining reinforcement
in those regions of a column that are.
expected to undergo cyclic inelastic deformations during a severe earthquake.
d) Provisions have been included for estimating the shear strength and flexural strength of
Provisions are also given for detailing of reinforcement
in the wall
shear wall sections.
web, boundary elements, coupling beams, around openings, at construction joints, and for
the development,
splicing and anchorage of reinforcement.
Whilst the common methods of design and construction
have been covered in this code, special
systems of design and construction of any plain or reinforced concrete structure not covered by
this code may be permitted on production of satisfactory
evidence regarding their adequacy for
seismic performance by analysis or tests or both.
The Sectional Committee responsible for the preparation
of this standard has taken into consibuilders and technologists and
deration the view of manufacturers,
users, engineers, architects,
has related the standard to the practices followed in the country in this field. Due weightage has
also been given to the need for international
co-ordination
among standards prevailing in
different seismic regions of the world.
In the formulation of this standard, assistance has been derived from the following publications:
requirements
for reinforced
concrete
and
i) AC1 318-89/318R-89,
Building
code
commentary, published by American Concrete Institute.
of reinforced
concrete
shear
walls and frame joints :
ii) ATC-11. Seismic resistance
Implications
of recent research for design
engineers,
published
by Applied
Technology Council, USA.
structures
for buildings,
Canadian
iii) CAN3-A23. 3-M84, 1984, Design of concrete
.
Standards Association.
iv) SEADC, 1980, Recommended lateral force requirements and commentary,
published by
Structural Engineers Association of California, USA
The composition of the technical committees responsible
for formulating this standard is given
in Annex A.

IS 13920 : 1993

Indian Standard

DUCTILE DETAILING OF REINFORCED

CONCRETE STRUCTURES SUBJECTED TO
SEISMICFORCES -CODEOFPRACTICE
1 SCOPE

3 TERMINOLOGY

1.1 This standard

3.0 For

the purpose of this standard,

following definitions shall apply.

covers the requirements

for
designing and detailing of monolithic
reinforced concrete buildings so as to give them adequate toughness and ductility to resist severe
earthquake shocks without collapse.

3.1 Boundary Elements

Portions along the edges of a shear wall that
are strengthened by longitudinal and transverse
reinforcement.
They tiay have the same thickness as that of the wall web.

1.1.1 Provisions of this code shall be adopted

in all reinforced
concrete
structures
which
satisfy one of the following four conditions.

a) The structure

is located

in seismic

3.2 Crosstie

zone

Is a continuous bar having a 135 hook with a

IO-diameter extension ( but not < 75 mm)
at each end. The hooks shall engage peripheral
longitudinal bars.

IV or V;

b) The

structure is located in seismic

III and has the importance
factor
greater than 1.0;

zone
(I )

3.3 Curvature

cl The structure

is located in seismic zone

III and is an industrial structure; and

The structure is located in seismic

III and is more than 5 storey high.

zone

3.4 Heap
Is a closed stirrup having a 135 hook with a
lo-diameter
extension
( but not < 75 mm )
at each end, that is embedded in the confined
core of the section.
It may also be made of
two pieces of reinforcement; a U-stirrup with a
135 hook and a lo-diameter extension (but not
< 75 mm ) at each end, embedded
in the
confined core and a crosstie.

1.1.2 The provisions for reinforced

concrete
construction given herein apply specifically
to
monolithic
reinforced
concrete construction.
Precast and/or prestressed
concrete members
may be used only if they can provide the same
level of ductility as that of a monolithic
reinforced concrete
construction
during or after
an earthquake.

3.5 Lateral Force Resisting System

2 REFERENCES
necessary

Indian Standards
listed
adjunct to this standard:

IS No.
456 : 1978

1786 : 1985

1893 : 1984

below

Is that part of the structural

system
resists the forces induced by earthquake.

are

which

3.6 Shear Wall

Title

A wall that is primarily designed to resist lateral

forces in its own plane.

Code of practice for plain and

reinforced
concrete
( third
revision )
Specification for high strength
deformed steel bars and wires
for concrete
reinforcement
( t&d revision )

Ductility

Is the ratio of curvature at the ultimate strength

of the section to the curvature at first yield of
tension steel in the section.

NOTE - The definition of seismic zone and importance factor are given in IS 1893 : 1984.

2.1 The

the

3.7 Sbell Concrete

Concrete that is not confined by transverse
.reinforcement,
is also called concrete cover.
3.8 Space Frame
A three dimensional structural system composed
of interconnected
members, without shear or
bearing walls, so as to function as a complete

Criteria for earthquake design

of structures (fourth revision )
1

IS 13920 : 1993
self-contained
unit with or without the aid of
horizontal diaphragms or floor bracing systems.

Mu

3.8.1 Vertical Load Carrying Space Frame

MAh

A space
loads.

frame

designed

to carry

all vertical

llrn

MAs

9 lim

3.8.2 nloment Resisting Space Frame

MIh*lm

A vertical load carrying space frame in which

the members and joints are capable of resisting
forces primarily by flexure.

MB
u, Ilm
ML

4 SYMBOLS

For the purpose of this standard, the following

letter symbols shall have the meaning indicated
against each; where other symbols are used, they
are explained at the appropriate
place.
All
dimensions are in mm, loads in Newton and
stresses in MPa ( N/sq mm ) unless otherwise
speciried.

43
Ah
4
dk

ASd
A sh
A st
A
CW,
D
Dk
d
dw
E9

fck
fY
h

gross cross sectional area of column,

wall
horizontal reinforcement area within
spacing S,
area of concrete core of column
reinforcement
along each diagonal
of coupling beam
area of cross section of bar forming
spiral or hoop
- area of uniformly distributed
vertical reinforcement
vertical reinforcement at a joint
centre to centre distance between
boundary elements
overail depth of beam
diameter of column core measured
to the outside of spiral or hoop
-_ eiffective depth of member
effective depth of wall section
elastic modulus of steel
characteristic
compressive
strength
of concrete cube
yield stress of steel
longer
dimension
of rectangular
confining
hoop
measured
to its
outer face
storey height
clear span of beam
length
of member
over which
special confining reinforcement
is
.to be provided
horizontal length of wall
clear span of coupling beam

9 IIrn
bR

u, Hul

MU

P
s

sv

1,
V

D+L

,DcL

Vj

Vu

V,

&I, X:

PC

Pmax

Pmlo

742

%nax

5 GENERAL

factored design
wall section
hogging
beam at
sagging
beam at
hogging
beam at
sagging
beam at
moment
framing
moment
framing

moment

on entire
\

moment of resistance
of
end A
moment of resistance
of
end A
moment of resistance
of
end B
moment of resistance of
end B
of resistance
of beam
into column from the left
of resistance
of beam
into column frcm the right

flexural strength of wall web

factored axial load
pitch of spiral or spacing hoops
vertical spacing of horizontal reinforcement in web
thickness of wall web
shear at end A of beam due to dead
and live loads with a partial factor
of safety of 1.2 on loads
shear at end B of beam due to dead
and live loads with a partial factor
of safety of 1.2 on loads
shear resistance at a joint
factored shear force
shear force to be resisted by reinforcement
depth of neutral axis from extreme
compression fibre
inclination
of diagonal
reinforcement in coupling beam
vertical reinforcement
ratio
compression reinforcement
ratio in
a beam
maximum
tension
reinforcement
ratio for a beam
minimum
tension
reinforcement
ratio for a beam
shear strength of concrete
maximum permissible shear
in section
nominal shear stress

stress

SPECIFICATION

5.1 The design and

cczstruction
of reinforced
concrete buildings sha.11be governed by the provisions of IS 456 : 1978, except as modified by
the provisions of this code.
2

IS13920:1993

5.2 For all buildings which are more than 3

storeys in height, the minimum grade of concrete
shall preferably be M20 ( fCk = 20 MPa ).

Ld

+lOdb

5.3 Steel reinforcements

of grade Fe 415 ( see
IS 1786 : 1985 ) or less only shall be used.
6 FLEXURAL

MEMBERS

6.1 General
These requirements
apply to frame members
resisting earthquake induced forces and designed
These members shall satisfy
to resist flexure.
the following requirements.

a
z
;
c:

6.1.1 The factored

under earthquake
0.1 fck.

-I

axial stress on the member

loading shall not exceed

6.1.2 The member shall preferably

width-to-depth
ratio of more than 0.3.

have

L,, = DEVELOPMENT

--I-!-+-

FIG. 1

LENGTH

IN TENSION
db = BAR

DIAMETER

ANCHORAGE OF BEAM BARS IN AN

6.1.3 The width of the member shall not be less

than 200 mm.

EXTERNAL JOINT

6.1.4 The depth D of the member shall preferably be not more than l/4 of the clear span.

6.2.6 The longitudinal bars shall be spliced, only

if hoops are provided over the entire splice
length, at a spacing not exceeding 150 mm (see

6.2 Longitudinal

Fig. 2 ). The lap length shall not be less than

the bar development
length
in tension.
Lap
splices shall not be provided
(a) within
a joint,
tb) within a distance
of 2d from joint
face, and
(c) within a quarter lengh of the member
where
flexural yielding may generally
occur
under the
effect of earthquake
forces.
Not more than

6.2.1

Reinforcement

a) The top as well as bottom reinforcement shall consist of at least two bars
throughout the member length.

b) The tension steel ratio on any face, at

any section, shall
-- not be less than 50 percent of the bars
&in = 0.24 ,/fc&,;
where fck andf, section.
are in MPa.
6.2.2 The

maximum
section,
shall

at any

steel

one

at that

and not

for lateral

t_d = DEVELOPMENT

LENGTH

IN TENSION

load

moments.
6.2.5

at

face must be

6.2.4 The steel provided

at each of the top and
bottom face of the member at anv section along
its length shall be at least equal to one-fourth
of
the maximum negative
moment
steel provided
It may be clarified
at the face of either joint.
that redistribution
of moments
permitted
in
IS 456 :I978 ( clause 36.1 ) will be used only for

load moments

be spliced

steel ratio on any face

not exceed pmax = 0.025.

6.2.3 The positive steel at a joint

at least equal to half the negative
face.

vertical

shall

db =

BAR

DIAMETER

In an external

joint, both the top and the

bottom
bars of the beam shall be provided
with
anchorage length, beyond the inner face of the
column,
equal to the development
length
in
tension plus 10 times the bar diameter
minus
the allowance
for 90 degree
bend(.s ). ( see
joint,
both face bars
Fig. 1 ). In an internal
of the beam shall be taken continuously
through

FtG. 2

LAP, SPLICE IN BEAM

6.2.7 Use of welded

splices
and mechanical
connect,ions
may also be made,
as per 25.2.5.2
of IS 456 : 1978. However,
not more than half
the reinforcement
shall be spliced
at a section
where flexural
yielding
may take place.
The
location
of splices shall be governed
by 62.6.
.

the column.
3

IS 13920 : 1993
6.3 Web Reinforcement

6.3.2 The minimum diameter of the bar forming a hoop shall be 6 mm. However, in beams
with clear span exceeding 5 m, the minimum
bar diameter shall be 8 mm.

6.3.1 Web reinforcement

shall consist of vertical hoops.
A vertical hoop is a closed stirrup
having a 13.5 hook with a 10 diameter extension ( but not < 75 mm ) at each end that is
embedded in the confined core ( see Fig. 3a ).
In compelling
circumstances,
it may also be
made up of two pieces of reinforcement;
a
U-stirrup with a 135 hook and a 10 diameter
extension ( but not c 75 mm ) at each end,
embedded in the confined core and a crosstie
( see Fig. 3b ). A crosstie is a bar having a
135 hook with a 10 diameter extension ( but
not < 75 mm ) at each end. The hooks shall
engage peripheral longitudinal bars.
i)

a) calculated
factored
analysis, and

shear

force

as per

b) shear force due to formation

of plastic
hinges at both ends of the beam plus the
factored gravity load on the span. This
is given by ( see Fig. 4 ):

for sway to right:

V,,

YC Vi+

and Vu,b ii)

6.3.3 The shear force to be resisted by the vertical hoops shall be the maximum of :

VF

14
C

1.41:

M uAslim
f M: hlim
_-._z__-L
Mt,*ii,

-I- *G, iim

LAB *

1, and

for sway to left:

V,(I =

vD+L

and V,,b =VisL~

1.4 [ M$h,i;t
14

M?,?i,
c

M::ii,

+ ME,ii,
,
L *II
I

whereMt,*li,, Mthfi, and M,BI:t,,,, Mfh,i, are the sagging and hogging moments of resistance
of the beam section at ends A and B,respectively. These are to be calculated as per IS 456 : 1978.
LAB is clear span of beam. Vt+L and VE*L are the shears at ends A and B, respectively,
due to
vertical loads with a partial safety factor of 1.2 on loads. The design shear at end A shall be
Similarly, the design shear at end B shall
the larger of the two values of Vu,r, computed above.
be the larger of the two values of Vu,b computed above.
I

HOOP

U-STIRRUP

-/

(aI

I b)
Fib.

BEAMWEB RE~NFORCBMBNX

1s 13920 : 1993

WL= vi+L
a

= vi+L
V
u,a

t
u,b

V
u,a

u.

= 1.2 to+ L)
2

1
AS

4
Bh
Mu,lim +Mu,lim

-1.4
I

CAB

Bh

D+L+, .4
b = b,

Mu,Iim

+ MuJim

LAB

tSWAYG,GtiT)
Ah

Ah

Rii

M u,lim

Mu, lim

vu.a

LAB

Ah
Mu, lim

vu,b = vb D+L_,.4

Bs
+Mu,lim

LAI3

CALCULATIONOF DESIGNSHEARFORCEFOR BEAM

6.3.4 The contribution

of bent
inclined hoops to shear resistance
shall not be considered.

up bars and
of the section

6.3.5 The spacing of hoops over a length of 2d

at either end of a beam shall not exceed ( a )
d/4, and (b) 8 times the diameter of the smallest
longitudinal bar; however,
it need not be less
than 100 mm ( see Fig. 5 ). The first hoop shall
be at a distance not exceeding 50 mm from the
joint face. Vertical hoops at the same spacing
as above, shall also be provided over a length
equal to 2d on either side of a section where
flexural yielding may occur under the effect of
earthquake forces. Elsewhere, the beam shall
have vertical hoops at a spacing not exceeding
d/2.
7 COLUMNS

AND FRAME MEMBERS SUBTO BENDING AND AXIAL LOAD

7.1 General
7.1.1 These requirements

+ Mu,iim

TD LEFT)

FIN. 4

JECTED

Va

Bs

Mu,tim

Vu,b

(SWAY

vu,a

D+L+l.4

apply to frame members which have a factored

axial stress in
excess of O-1 fck under the effect of earthquake
forces.

7.1.2 The minimum

dimension of the member

shall not be less than 200 mm. However, in
frames which have beams with centre to centre
span exceeding 5 m or columns of unsupported
length exceeding 4 m, the shortest dimension of
the column shall not be less than 300 mm.
7.1.3 The ratio of the shortest cross sectional
dimension to the perpendicular dimension shall
preferably not be less than 0.4.
7.2 Longitudinal

Reinforcement

7.2.1 Lap splices shall be provided

only in the
central half of the member length. It should be
proportioned as a tension splice. Hoops shall be
provided over the entire splice length at spacing
not exceeding 150 mm centre to centre. Not
more than 50 percent
of the bars shall be
spliced at one section.
7.2.2 Any area of a column that extends more
than 100 mm beyond the confined core due to
architectural
requirements, shall be detailed in
the following manner. In case the contribution
of this area to strength has been considered,
then it will have the minimum longitudinal and
transverse
reinforcement
as per this code,

IS 13920: 1993
MIN

ZBARS

ALONG

AS 3 Q MIN.
ASS

FOR

TOP

FULL

AND

LENGTH

BOTTOM

FACE

Bd

QEtAx.Bd

II
1

HOOP

HOOP

SPACING

SPACING

s dl

AND

8db

B = BREADTH
db=

FIG. 5

MINIMUM
\\AS

AND

PER

IS

OF

BEAM
LONGITUDINAL

7.3.2 The parallel legs of rectangular

hoops
shall be spaced not more than 300 mm centre
to centre. If the length of any side of the hoop
exceeds 300 mm, a crosstie shall be provided
( Fig. 7B ). Alternatively, a pair of overlapping
hoops may be provided within the columm ( see
Fig. 7C ). The hooks shall engage peripheral
longitudinal bars.

LONGITUDINAL
.TRANSVERSE

OF

BEAM REINFORCEMENT

Rowever, if this area has been treated as nonstructural, the minimum reinforcement
requirements shall be governed
by IS 456 : 1978
provisions minimum longitudinal and transverse
reinforcement,
as per IS 456 : 1978 ( see Fig. 6 ).

DIAMETER
BAR

STEEL

456 ; 1978

7.3.3 The spacing of hoops shall not exceed

half the least lateral dimension of the column,
except where special confining reinforcement
is
provided, as per 7.4.
7.3.4 The design shear force
be the maximum of:
a) calculated
factored
analysis, and
b) a factored

for columns
shear

shall

force as per

shear force given by

I-

FIG. 6 REINFORCEMENT
REQUIREMENT
FOR
COLUMNWITH MORE THAN 100 mm
PROJECTIONBEYONDCOW
7.3 Transverse

moment
of
where M,b,i, and M,bRlim are
resistance, of opposite sign, of beams framing
into the column
from opposite faces ( see
Fig. 8 ); and h,t is the storey height. The beam
moment capacity
is to be calculated as per
IS 456 : 1978.

Reinforcement

7.3.1 Transverse
reinforcement
for circular
columns shall consist of spiral or circular hoops.
In rectangular columns, rectangular hoops may
be used. A rectangular hoop is a closed stirrup,
having a 135 hook _with a 10 diamee;; extension
that IS
( but not < 75 mm ) at each
embedded in the confined core ( see iig 7A ).

7.4 Special Confining Reinforcement

This requirement
shall be met with, unless a
larger amount of transverse
reinforcement
is
required from shear strength considerations.
6

IS 13920: 1993

h,2309
PROVIDE

il~4
h SHALL
h,

AND

300mim
BE

LARGER

OF

B,
h SHALL

7A

SINGLE

mm

A CROSSTlE

HOOP

7B

BE

LARGER

OF

tic

3fNGLE
HOOP WITH
CROSSTIE

AND

Bc

h,>JOOmm
10 d (375mm)

,rCROSSflE

h SHALL
7C

BE

OVERLAPPING

LARGER
HOOPS

OF

h),

WITH

AND
A

B,

CRCSSTIE

FIG. 7 TRANSVERSE
REINFORCEMENT
IN COLUMN

(EC s 306 m

ml

IS 13920 : 1993

7.4.1 Special confining reinforcement

shall be
provided over a length I, from each joint face,
towards midspan, and on either side of any
where flexural yielding may occur
section,
under the effect of earthquake
forces ( see
Fig. 9. ). The length (lo* shall not be less than
( a ) larger lateral dimension of the member at
the section where yielding occurs, ( b ) l/6 of
clear span of the member, and ( c ) 450 mm.
7.4.2 When a column terminates
into a footing
or mat, special confining reinforcement
shall
extend at least 300 mm into the footing or mat
( see Fig. 10 ).
7.4.3 When the calculated
point
of contraflexure, under the effect of gravity and earthquake loads, is not within the middle half of
the member clear height, special confining
reinforcement
shall be provided over the full
height of the column.

v,

7.4.4 Columns supporting

reactions
from discontinued
stiff members, such as walls, shall
be provided with special confining reinforcement over their full height ( see Fig. I1 ). This
reinforcement
shall also be placed above the
discontinuity
for at least the development
length of the largest longitudinal
bar in the
column. Where the column is supported
on a
wall, this reinforcement
shall be provided over
the full height of the column; it shall also be
provided below the discontinuity
for the same
development length.
confining reinforcement
shall be
provided over the full height of a column which
has significant variation
in stiffness along its
height. This variation
in stiffness may result

%t

+I
-vu
hlbk
u.lim

vu : 1.4
(

7.4.5 Special

FIG.

ubRlim
,

hst

CALCULATION OF DESIGN SHEAR

FORCB POR tiLUMN

--I:

AS

REINFORCEMENT

SPLICE_

7-3-3
I-

REINFORCEMENT

CONFINING
7-4.1

PER

TRANSVERSE

SPECIAL
AS PER

IS ,13920 :

1993
SHE AR WALL
DEVELOPMENT
LENGTH

OF

L ONGI TUDINAL
BAR

FIG. 11

SPECIAL
CONFINING
RBINFORCHMENT
REQUIREMENT
FORCOLUMNS
UNDER
DISCONTINUED
WALLS

due to the presence of bracing, a mezzanine

floor or a R.C.C. wall on either side of the
column that extends only over a part of the
column height ( see Fig. 12 ).
7.4.6 The spacing of hoops used as special
confining reinforcement
shall not exceed l/4 of
minimum member dimension but need not be
less than 75 mm nor more than 100 mm.
7.4.7 The area of cross section, Ash, of the bar
forming circular hoops or spiral, to be used as
special confining reinforcement,
shall not be
less than
Ash = 0.09 SD+[$-

1.0)

where
A gh = area of the bar cross section,
= pitch of spiral or spacing of hoops,
S
DB: - diameter of core measured to the
outside of the spiral or hoop,
compressive
strength
fCL = characteristic
of concrete cube,
yield stress of steel ( of circular
fY
=
hoop or spiral ),
Ag = gross area of the column cross
section, and

Ak = area of the concrete

core =$ DI

Example : Consider a column of diameter 300

mm. Let the grade of concrete be M20, and
that of steel Fe 415, for longitudinal
and
confining reinforcement.
The spacing of circular hoops, S, shall not exceed the smaller of
( a ) l/4 of minimum
member
dimension =
l/4 x 300 = 75 mm, and ( b ) 100 mm. Therefore, S = 75 mm. Assuming 40 mm clear cover
to the longitudinal .reinforcement
and circular
hoops of diameter 8 mm, DL = 300-2 x 40 +
2 x 8 = 236 mm. Thus, the area of cross
section of the bar forming circular hoop works
out to be 47.28 mm*. This is less than the cross
sectional area of 8 mm bar ( 50-27 mm* ). Thus.
circular hoops of diameter 8 mm at aspacing
of 75 mm centre to centre will be adequate.
7.4.8 The area of cross section, Agh, of the bar
f orming rectangular hoop, to be used as special
confining reinforcement
shall not be less than
A gh s 0.18 Sh jik Ag
~&?O]
where
h = longer dimension of the
confining hoop measured

rectangular
to its outer

.
10

TS 13920 : l!J93
SPACE

FOR

UNSUPPORTED
LENGTH
OF

t- VENTILATORS

COLUMN

SHEAR
\ FAILJRE

PANEL/R

C WALL

(I),

2).

(3) and (4) relatively

FIG.

face. It shall not

Fig. 7 ), and
AB: =

exceed

stiff columns

They attract

parge seismic

shear force.

12 COLUMNSWITH VARYINGSTIFFNESS

either a pair of overlapping hoops or a single

hoop with crossties, in both directions, will have
to be provided.
Thus, the dimension h.will
b&FJarrr
z:(i)
59012 = 295 mm, and (ii)
. The spacmg of hoops, $,
shall not exceed the smaller of (a) l/4 of minimum member dimensions = l/4 x 500 = 125
mm, and (b) 100 mm. Thus, S = 100 mm. The
area of cross section of the bar forming rectangular hoop works out to be 64.47 mm*. This
is less than the area of cross section of 10 mm
bar ( 78.54 mm* ). Thus, 10 mm diameter rectangular hoops at 100 mm c/c will be adequate.
Similar calculations
indicate that, as an alternative, one could also provide 8 mm diameter
rectangular hoops at 70 mm c/c.

300 mm ( see

area .of confined concrete

core in the
rectangular hoop measured to its outside dimensions.

NOTE : The dimension

4 of the hoop could be
reduced by introducin
crossties,
as shown in Fig. IB.
In this case, Ak shal !! be measured
as the overall
core area, regardless of the hoop arrangement.
The
hooks of crossties shall engage
peripheral
longitudinal bars.

Example

: Consider a column
of 650 mm x
500 mm. Let the grade of concrete be M20
and that of steel Fe 415,. for the longitudinal
Assuming clear
and coufining reinforcement.
cover of 40 mm to the longitudinal
reinforcement and rectacgular hoops of diameter 10 mm,
the size of the core is 590 mm x 440 mm. As
both these dimensions are greater than 300 mm,

8 JOINTS OF FRAMES
confining reinforcement
as
special
required at the end of column shall be provided
8.1 The

.
11

IS 13920 : 1993
9.2.2 The design shear strength of concrete, Q,
shall be calculated
as per Table 13 of IS 456 :
1978.

through the joint as well, unless the joint is

confined as specified by 8.2.
8.2 A joint which has beams framing into all
vertical faces of it and where each beam width
is at least 3/4 of the column width, may be
provided with half the special confining reinforcement required at the end of the column. The
spacing of hoops shall not exceed 150 mm.

9.2.3 The nominal

shall not exceed
IS 456 : 1978.

9.2.4 When Tv is less than 7Fcshear

ment shall be provided in accordance
9.1.5 and 9.1.7.

9 SHEAR WALLS
9.1 General Requirements
9.1.1 The requirements of this section apply to
the shear walls, which are part of the lateral
force resisting system of the structure.

9.1.4 Shear walls shall be provided with reinforcement in the

longitudinal
and transverse
-directions in the plane of the wall. The minimum
reinforcement ratio shall be 0.002 5 of the gross
area in each direction. This reinforcement
shall
be distributed uniformly across the cross section
of the wall.
9.1.5 If the factored
shear stress in the wall
exceeds 0.25 dfz
or if the wall thickness
exceeds 200 mm, reinforcement shall be provided
in two curtains, each having bars running in the
longitudinal
and transverse
directions
in the
plane of the wall.
9 1.6 The diameter of the bars to be used in any
part of the wall shall not exceed l/lOth of the
thickness of that part.
9.1.7 The maximum spacing of reinforcement
in
either direction shall not exceed the smaller of
I&, 3 tw, and 450 mm; where Zwis the horizontal length ofthe wall, and tw is the thickness
of the wall web.
9.2 Shear Strength
9.2.1 The nominal
calculated as:

shear

stress,

r,,, shall

be

Vll
*v = tw
where
VU= factored shear force,
tw = thickness of the web, and
This
dw= effective depth of wall section.
may by taken as 0.8 I, for rectangular
sections.

reinforcewith 9.1.4

9.2.5 When Tv is greater

than Q, the area
of horizontal
shear reinforcement,
At,, to be
provided within a vertical spacing. S,, is given
by
V = @87fyA,4v

9.1.2 The thickness of any part of the wall shall

preferably, not be less than 150 mm.
9.1.3 The effective flange width, to be used in
the design of flanged wall sections, shall be
assumed to extend beyond the face of the web
for a distance which shall be the smaller of (a)
half the distance to an adjacent shear wall web,
and (b) l/IO th of the total wall height.

shear stress in the wall, rv,

Q, maX, as per Table 14 of

US

&

where Vus = ( Vu - 7c tw dw ), is the shear force

to be resisted by the horizontal reinforcement.
However, the amount of horizontal reinforcement provided shall not be less than the minimum, as per 9.1.4.
9.2.6 The vertical
reinforcement,
that
is
uniformly distributed
in the wall, shall not be
less than the horizontal
reinforcement
calculated as per 9.2.5.
9.3 Flexural Strength
9.3.1 The moment of resistance,
MUv, of the
wall section may be calculated
as for columns
subjected to combined bending and axial load
as per IS 456 : 1978. The moment of resistance
of slender ,rectangular shear wa!l section with
uniformly distributed
vertical reinforcement
is
given in Annex A.
9.3.2 The cracked flexural strength of the wall
section should be greater than its untracked
flexural strength.
9.3.3 In
elements,
centrated
centration
of 12 mm

walls that do not have boundary

vertical reieforcement
shall be conat the ends of the wall. Each conshall consist of a minimum of 4 bars
diameter arranged in at least 2 layers.

9.4 Boundary Elements

Boundary elements are portions along the wall
edges that are strengthened by longitudinal and
transverse reinforcement.
Though they may
have the same thickness as that of the wall web
it is advantageous to provide them with greater
thickness.
9.4.1 Where the extreme fibre compressive stress
in the wall due to factored gravity loads plus
factored
earthquake
force
exceeds 0*2f,k,
boundaty elements shall be provided along the
vertical boundaries
of walls. The boundary
12

Is 13920: 1993
,elements may be discontinued where the calculated compressive
stress becomes less than
compressive
stress shall be
0. Isfck. The
calculated using a linearly elastic model and
gross section properties.
9.4.2 A boundary element shall have adequate
axial load carrying capacity,
assuming short
column action, so as to enable it to carry an
axial compression equal to the sum of factored
gravity load on it and the additional
compressive load induced by the seismic force.
The
latter may be calculated as:
Mu - Mw
C

where
Mu = factored

design moment on the entire

wall section,
provided by
Mm = moment of resistance
distributed
vertical
reinforcement
across the wall section, and
distance between
cw - center to center
the boundary elements along the two
vertical edges of the wall.
9.4.3 If the gravity load adds to the strength of
the wall, its load factor shall be taken as 0.8.

where V,, is the factored shear force, and a is

the angle made by the diagonal reinforcement
with the horizontal.
At least 4 bars of 8 mm
diameter shall be provided along each diagonal.
The reinforcement along each diagonal shall be
enclosed by special confining reinforcement,
as
per 7.4. The pitch of spiral or spacing of ties
shall not exceed 100 mm.
9.5.3 The diagonal or horizontal
bars of a
coupling beam shall be anchored in the adjacent
walls with an anchorage length of 1.5 times the
develapment length in tension.
9.6 Openings in Walls
9.6.1 The shear strength of a wall with openings
should be checked along critical planes that
pass through openings.
9.6.2 Reinforcement
shall be provided along
the edges of cpenings in walls. The area of the
vertical and horizontal
bars should be such as
to equal that of the respective interrupted bars.
The vertical bars should extend for the full storey
height. The horizontal bars should be provided
with development length in tensron beyond the
sides of the opening.
9.7 Discontinuous Walls

9.4.4 The percentage of vertical reinforcement

in the boundary elements shall not be less than
O-8 percent, nor greater than 6 percent.
In
order to avoid congestion,
the practical upper
limit would be 4 percent.

Columns supporting discontinuous walls shall be

provided with special confining reinforcement,
as per 7.4.4.

9.4.5 Boundary
elements, where required, as
per 9.4.1, shall be provided throughout
their
height, with special confining reinforcement,
as
per 7.4.
9.4.6 Boundary elements need not be provided,
if the entire wall section is provided with
special confining reinforcement, as per 7.4.

The vertical reinforcement

ratio across a horizontal construction joint shall not be less than:

9.5 Coupled Shear Walls

9.5.1 Coupled shear walls shall be connected
by ductile coupling beams. If the earthquake
induced shear stress in the coupling beam
exceeds
0.1 Is 4fT
D

where Is is the clear

and D is its overall
induced shear and
resisted by diagonal

span of the coupling beam

depth, the entire earthquake
flexure shall, preferably, be
reinforcement.

9.5.2 The area of reinforcement to be provided

along each diagonal in a diagonally reinforced
coupling beam shall be:
VII
A ri 1.74fr sin a

9.8 Construction Joints

0.92

P
TV-A&!
>
(
where T,, is the factored shear stress at the joint,
P, is the factored
axial force ( positive for
compression ), and Ae is the gross cross
sectional area of the joint.
fv

9.9 Development,
Requirement

Splice

and

Anchorage

9.9.1 Horizontal
reinforcement shall be anchored near the edges of the wall or in the confined
core of the boundary elements.
9.9.2 Splicing of vertical Sexural reinforcement
should be avoided, as far as possible, in regions
where yielding may take place. This cone of
flexural yielding may be considered to extend
for a distance of JWabove the base of the wall
or one sixth of the wall height, whichever is
more. However, this distance need not be
greater than 2 fW. Not more than one third of
this vertical reinforcement
shall be spliced at
such a section.
Splices in adjacent bars should
be staggered by a minimum of 600 mm.
.

13

1s 13920: 1993

9.9.4 Welded splices and mechanical eonnections shall confirm to 25.2.5.2 of IS 456 : 1978.
However, not more than half the reinforcement
shall be spliced at a section, where flexural
yielding may take place.

9.9.3 Lateral ties shall be provided

around
lapped spliced bars that are larger than 16 mm
in diameter.
The diameter of the tie shall not
be less than one fourth that of the spliced bar
nor less than 6 mm. The spacing of ties shall
not exceed 150 mm center to center.

ANNEX A
( Clause 9.3.1 )
MOMENT

OF RESISTANCE

A-l The moment of resistance

distributed vertical reinforcement

OF RECTANGULAR

SHEAK WALL SECTION

of a slender rectangular
shear
may be estimated as follows:

wall section

with

uniformly

(a) For xo/lw Q x, /Iw,

where
o-003 5

ratio
p
= vertical reinforcement
area
of
uniformly
distributed
A St =
P = 0.87&,/( 0.003 5 EB ),

vertical

reinforcement,

Es = elastic modulus of steel, and

P = axial compression on wall.
(b) For x; /&v < x&i

< 1.0,

where
a1 =

0*36++

I -$-

&
)3

O.lS+$-

a2 =

1-e-g-

&)I

I_

The value of x,/l,, to be used in this equation,

should be calculated

from the quadratic

eqvation

where
CL,= ($-A

);andaa=

($-).

These equations were derived, assuming a rectangular wall section of depth 1~ and thickness tw
The vertical reinforcethat is subjected to combined uni-axial bending and axial compression.
ment is represented by an equivalent steel plate along the length of the section.
The stressstrain curve assumed for concrete is as per IS 456 : 1978 whereas that for steel IS assumed to be
Two equations are given for calculating
the flexural strength of the section.
Their
bi-linear.
use depends on whether the section fails in flexural tension or in flexural compression.
.

14

IS 13920 : 1993

ANNEX

( Foreword )
COMMIiTEE

COMPOSITION

Earthquake Engineering Sectional Committee, CED 39

Representing

Chlrman
7216 Civil

DR A. S. ARYA

Line,

Roorkee

Members
Indian-Roads

SHR1 0. P. AGGaRwaL
SHRI G. SHARAN ( Alternate )
DR K. G. BHATIA
DR C. KAMESHWARA RAO ( Aiternute )
SHRI A. K. SINGH ( Alternate)
SHRI S. C. BHATIA

Congress,

New Delhi

Bharat Heavy Electricals

National

DR B. K. RASTOGI ( Alternate )
Da A. R. CHANDRASEKARAN

Geophysical

Department
Roorkee

DR BRIIESH CHANDRA ( AIfernnte )

Da B. V. K. LAVANIA ( Alternate )
DR S. N. CHATTERJFE
SHRI S. K. NAQ ( Alternate )
SHRI K. 4. CHAUBAL
Da B. K. PAUL ( Alternate )
Da A. V. CHUMMAR
DR S. K. KAUSHIK ( Alternate )
DIRECTOR EMBANKMENT( N 8~ W )
DIRECTOR CMDD ( NW & S ) ( Afternate
DIRECTOR STANDARDS ( B 8r S ), RDSO
JOINT DIRECTOR STANDARDS ( B & S )
CB-I. RDSO, LUCKNOW ( Alternate )
KUMARI E. DIVATIA
SHRI C. R. VENKATPSHA ( Alternate )
SHRI I. D . GUPTA
SHRI J. G. PADALE ( Alternate )
SHRI V. K. K~LKARNI
SHRI P. C. KOTESWARA RAO ( Akrnute )
SHRI V. KUMAR
SHRI R. S. BAJAJ ( jilternah
)
SHRI M. Z. KURIEN
SHRI K. V. SUBRAMANIAN ( Alternate )
SHR~ A. K. LAL
SHRI T. R. BHATIA ( Alternate )
SHRI S. K. MITTAL
SHRI S. S. NARANG
SHRI A. D. NARIAN

Indian

cf

Ltd. New Delhi

Research

Earthquake

Meterological

Council,

Indian

of Earthquake

Water Commission

Railway

Board,

National
Central

of Atomic

Thermal

Tata Consulting
National

of Roorkee.

New Delhi

( ERDD

Roorkec

), New Delhi

of Railways
Power Corporation

Energy,

Station,

Engineers,

Ltd, New Delhi

Pune

Bombay

Power Corporation

Buildings

University

Technology,

Water & Power Research

Department
National

Ministry

Hydro-Electric

( CSIR ), Hyderabad

Shillong

Central

II

Engineering,

Department,

North Eastern
Society

Institute

Ltd, New Delhi

Bombay

Organization,

New Delhi

Central Building Research Institute,

Roorkee
Central Water Commission
( CMDD ), New Delhi
Ministry
of
Transport,
Department
of Surface
( Roads Wing ), New Delhi

Transport

SHRI 0. P. AGGARWAL ( Alternate )

Geological
Survey of India, Calcutta
SHRI P. L. NARULA
SHRI A K. SRIVASTAVA ( Afternate )
Irrigation Departmeot,
Govt of Maharashtra,
Nasik
RESEARCHOFFICFR
Engineers India Ltd, New Delhi
DR D. SENGUPTA
SHRI R. K. GROVER ( Alternate )
DR R. D. SHARMA
Nuclear Power Corporation,
Bombay
SHR~ U. S. P. VERMA ( Alternate )
Engineer-in-Chiefs
Branch, Army Headquarters,
New Delhi
COL R. K. SINGH
1,~.COLB.D. BHATTOPADHYAYA (Alternate)
DR P. SRJNIVASLJLU
Structural Engineering Research Centre ( CSlR ), Madras
Da N. LAKSHMANAN( Alternate )
Central Public Works Department,
New Delhi
SUPERINTENDING ENGINEER (D)
EXECUTIVEENGINEER (D) II ( Alternate )
DR A. N. TANDON
In personal
capacity
( B-7150 Safdarjung Development
Area,
SHR~ J. VENKATARAMAN,
Director ( Civ Bngg )

New Delhi )

Director

General,

BIS ( Ex-offjccio Member)

Secretary
SHRI S. S. SETHI
Director ( Civ Engg ), BIS
( Continued on pugs 16 )

1s

IS 13920: 1993
( Conrinuedfrom page 15 )

Earthquake Resistant Construction Subcommittee,

Convener

CED39:

Representing

DR A. S. ARYA

( 72/6 Civil Lines, Roorkee )

Members

Engineer-in-Chief% Branch, New Delhi

Housing and Urban Development Corporation,

SHRIN.K.BHATTACHARYA
SHRI B. K CHAKRABORTY
!&RI D. P. SIN~H ( AItermte )
SHRI D. N. GHOSAL
DR SUDHIR K. JAIN

North Eastern Council, Shilloog

Indian Institute of Technology, Kaopur

SHRI

Central Buildings Research Institute. Roorkee

Railway Board ( Ministry of Railways )

DR A. S. R. SAI ( Altwnute )

M. P. JAISINQH

JOINT DIRECTORSTANDARDS( B & S ) CB-1

ASSISTANTDIRECTOR( B 8t S ), CB-1
( Alternate )
SHRI

SHRI .V. K. KAPOOR( Alterate

SHRI

P&taWorks

V. KAPUR
hp.

Department,

Government

New Delhi

of Hhoachal Pradesh,

Hindustao Prefab Limited, New Delhi

National Buildings Organization,
New Delhi

KUNDU

SHRI A.

K. LAL
Soar T. R. BHATIA( Alternate )
DR B. C. MATHUR

U~~o~i;;

of Rocrkee,

Department

of Earthquake

Engineering,

Da ( SHRIMATI) P. R. Bose ( Alternate )

$HRI.G. M. SHOUNTHU
?R P. SRINNWIJLU

Public Works Department, Jammu & Kashmir

Structural Engineering Research Ceotre ( CSIR ), Madras

Da N. LAKSHMANAN
( Alternote )
SHM SUBRATACHAKRAVARTY

Public Works Department, Government of Assam, Gauhati

Publiog Works Department, Government of Gujrat
New Delhi
SUPPRINTBNDINO
SURVEYOROF WORKS NDZ ) Central Public Works Department,

SUPERINTENDING
ENQIN~ER ( DIISIQN)

SUPERINTENDENCY
ENCHN~ER(D) ( 1 ltemu~e )

16

Hureau of Indian Standards

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Amendments are issued to standards as the need arises on the basis of comments. Standards are also
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of Indian Standards should ascertain that they are in possession of the latest amendments or edition by
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This Indian Standard has been developed from Dot : No. CED 39 ( 5263 )

Amendments

Issued Since Publication

Date of Issue

Amend No.

Text Affected

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Printed at Dee Kay Printers, New Delhi-l 10015, India.

AMENDMENT

NO. 1 NOVEMBER 1995

TO
IS 13920 : 1993 DUCTILE DETAILING OF
REINFORCED CONCRETE STRUCTURES SUBJECTED
TO SEISMIC FORCES - CODE OF PRACTICE
[ Page 3, clause 6.2.1(b)
] - Substitute the following for the existing
formula:
p min= 0.24@&'fy

(CED39)
Printed at Dee Kay Printers, New Delhi, India

AMENDMENT

NO. 2 MARCH 2002

TO
IS 13920:1993
DUCTILE DETAILING OF REINFORCED
CONCRETE STRUCTURES SUBJECTED TO SEISMIC
FORCES CODE OF PRACTICE
( Page 1, clause 1.1.1) Substitute the following for the existing
1.1.1 Provisions of this code shall be adopted in all reinforced concrete
structures which are located in seismic zone III, IV or V.

( Page 3, clause 5.2, line 3 ) Delete the word preferably.

( Page 3, c[ause 5.3 ) Insert the following at the end of the clause:
However, high strength deformed steel bars, produced by the thermomechanical treatment process, of grades Fe 500 and Fe 550, having elongation
more than 14.5 percent and conforming to other requirements of IS 1786: 1985
may also be used for the reinforcement.

(CED 39 )

Reprography Unit, BIS, New Delhi, India