IS 1893-4: Criteria for earthquake resistant design of structure, Part 4: Industrial structures including stack-like structures )

2005·2.1 MB·English

by  Bureau of Indian Standards

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IS 1893-4 (2005): Criteria for earthquake resistant design
of structure, Part 4: Industrial structures including
stack-like structures ) [CED 39: Earthquake Engineering]
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IS 1893 (Part 4) :2005

Indian Standard
CRITERIA FOR EARTHQUAKE RESISTANT
DESIGN OF STRUCTURES
PART 4 INDUSTRIAL STRUCTURES INCLUDING
STACK-LIKE STRUCTURES
ICS 91.120.25

(3BIS2005
BUREAU OF INDIAN STANDARDS
MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI 110002
August 2005 Price Group 9
Earthquake Engineering Sectional Committee, CED 39
FOREWORD
This Indian Standard (Part 4) 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.
Hinlalayan-Naga Lushairegion, Indo-Gangetic Plain,WesternIndi%KutchandKathiawar regionsaregeologically
unstable parts of the country where some devastating earthquakes of the world have occurred. A major part of
thepeninsular Indiahasalsobeen visitedbystrong earthquakes, butthesewererelatively fewinnumber occurring
at much larger time intervals at any site, and had considerably lesser intensity. The earthquake resistant-design
ofstructures, taking intoaccount seismicdatafrom studiesoftheseIndian earthquakes, hasbecome very essential,
particularly inview of heavy construction programme atpresent all over the country. It isto serve this purpose
that IS 1893 : 1962 ‘Recommendations for earthquake resistant design of structures’ was published and
subsequently revised in 1966, 1970, 1975and 1984.
in view of the present state of knowledge and in order to update this standard, the committee has decided to
cover the provisions for different types of structures in separate parts. This standard has been split into five
parts. Other parts inthis series are :
Part 1 General provisions and buildings
Pafl.2 Liquid retaining tanks-elevated and ground supported
Part”3 Bridges and retaining walls
Part 5 Dams and embankments
Part I contains provisions that are general in nature and applicable to a[ltypes of structures. Also, it contains
provisions that are specific to buildings only. Unless stated otherwise, the provisions inPart2 to Part 5shall be
read necessarily in conjunction with Part 1.
This standard contains provisions on earthquake resistant design of industrial structures including stack-like
structures. Industrial structures are covered in Section 1and Stack-like structures are covered in Section 2.
All sub-clauses under the main clause 0.0 of 1S1893(Part 1)are also applicable to this part except the 0.4.1.

Inthepreparation ofthisstandard co n siderable assistancehasbeenprovided byBHEL, IITRoorkee, IITBombay,
[IT Kanpur, NTPC, EIL, TCE, DCE, NPC and various other organizations.
Forthe purpose of deciding whether a particular requirement of this standard iscomplied with, thefinal value,
observed or calculated, expressing the result of a test or analysis, shall be-rounded off in accordance with
IS2: 1960 ‘Rules for rounding off numerical values (revised)’. The number of significant places retained inthe
rounded off value should be the same as that of the specified value inthis standard.
IS 1893 (Part 4):2005
Indian Standard
CRITERIA FOR EARTHQUAKE RESISTANT
DESIGN OF STRUCTURES
PART 4 INDUSTRIAL STRUCTURES INCLUDING
STACK-LIKE STRUCTURES
1SCOPE In addition to the above, the following structures are
classified.asstack-like structures and are covered by
1.1 The industrial structures shall be designed and
this standard:
constructed to resist the earthquake effects in
a) Cooling towers and drilling towem;
accordance with the requirements and provisions of
this standard. This standard describes the procedures b) Transmission and communication towers;
for earthquake resistant design of industrial structures.
c) Chimneys and stack-like structures;
It provides the estimates of earthquake loading for
d) Silos (including parabolic silos used for urea
design of such structures.
storage);
1.2 All sub-clauses under 1 of IS 1893 (Part 1)are
e) Support structures forrefinery columns, boilers,
also applicable to this part except 1.1.
crushers, etc; and
1.3 This standard deals with earthquake resistant f) Pressure vessels andchemical reactor columns.
design of the industrial structures (plant and auxiliary
2 REFERENCES
structures) including stack-like structures associated
with the following industries: The following standards contain provisions which,
a) Process industries; through reference inthis text, constitute provisions of
this standard. At the time of publication the editions
b) Power plants;
indicated were valid. All standards are subject to
c) Petroleum, fertilizers and petro-chemical revision and parties to agreements based on this
industries; standard are encouraged to investigate the possibility
of applying the most recent editions of the standards
d) Steel, copper, zinc and aluminum plants;
indicated ~elow:
e) Pharmaceutical plants;
1S No. Title
f) Cement industrie~
456:.2000 Code of practice for plain and
g.)Automobile industries;
reinforced concrete ~ourth revision)

h) Sugar and alcohol industries;
800:1984 Code of practice for general
j) Glass and ceramic industries; construction in steel (second
k) Textile industries; revision)
in) *Foundries; 875 Code of practics for design loads
(other than earthquake) for building
n) Electrical and electronic industries;
structures:
P) Consumer product industries;
(Part 1): 1987 Dead loads — Unit weights of
q) Structures for sewage and water treatment building material and stored
plants and pump houses;
materials (second revision)
r) Leather industries;
(Part 2): 1987 Imposed loads (second revision)
s) Off-shore structures and marine/potiharbour
(Part 3): 1987, Wind loads (second revision)
structures;
(Part 4): 1987 SrTow loads (second revision)
t) Mill structures;
(Part 5): 1987 Special loadsandloadcombinations
11)Telephone exchanges;
(second revision)
v) Water and waste water treatment facilities; and
1343:1980 Code of practice for prestressed
w) Paper plants.
concrete (second revision)
This standard shall also be considered applicabl e to 1888:1982 Method of loadtest onsoils (second
the other industries not mentioned above. revision)
1
IS 1893 (Part 4) :2005
1S No. Title EL — Response quantity due to earthquake
load
1893 (Part 1): Criteria for earthquake resistant
2002” design ofstructures: Part lGeneral ELX — Response quantity due to earthquake
provisions and buildings loads inX-direction
4326: 1993 Earthquake resistant design and
EL, — Response quantity due to earthquake
construction ofbuildings —Codeof
loads in Y-direction
practice (second revision)
ELZ — Response quantity due to earthquake
4998 (Part 1): Criteria for design of reinforced
loads in Z-direction
1992 concrete chimneys: Part 1
Assessment of loads (second e. — Static eccentricity at floor, i
s>
revision)
g— Acceleration due to gravity
6403: 1981 Code of practice for determination
of bearing capacity of shallow [— Importance factor
foundations (fh-st revision)
IL — Responsequantity dueto imposed loads
6533 (Part 2) Code of practice for design and
1989 construction of steel chimney: M— Mass matrix of the structural system
Part 2 Structural aspects (first
revision) M, — Mass matrix .ofthe primary system
13920: 19C3 Ductile detailing of reinforced IVICE — Maximum considered earthquake
concrete structures subjected to
M, — Total massofallthe equipment that are
seismic forces
flexible mounted at different locations
SP6 (6) : 972 Handbook for structural engrneers inthe structure
— Application of plastic theory in
design of steel structures h, — Modal mass of mode, k
3 GENERAL TERM-INOLOGY FOR MK — Total massofalltheequipment that are
EARTHQUAKE ENGINEERING rigidly mounted at different locations
inthe structure
All sub-clauses under 3 of IS 1893 (Part 1)are also
applicable to this stan-dard. M, — Total mass of structural system, which
supports secondary system
4 TERMINOLOGY FOR INDUSTRIAL
STRUCTURES R— Response reduction factor
The following definition and the others given r— Number of modes being considered

in IS 1893 (Part 1) except 4.10 and .4.16 are
s, — Spectral acceleration
applicable.
4.1 Combined Structures S;g — Spectral acceleration coefficient
SIDL — Super imposed dead loads
A structure with lateral load resisting element+
constructed from a combination of reinforced/ N— Standard penetration test value (SPT
prestressed concrete and structural steel. value) of the soil
5 SYMBOLS SRSS — Square root of sum of squares
5.I Symbols and notations applicable toSection 1are T— Undamped natural period of vibration
given as under: of the structure
/1,, — Design horizontal seismic coefficient Wi — Seismic weight of floor, i
b, — Floor plan dimension of floor i, z— Zone factor
perpendicular to direction of force
Oj — jth normalized mode shape
c— Index for closely spaced modes
ub — Influence vector-displacement vector of
CQC — Complete quadratic combination the structural system
method
Qik — Mode shape coefficient at floor, i, in
DL — Response quantity due to dead load mode, k

Cd, — Design eccentricity at floor, i Q. — Mode vector value from the primary
c1
~
IS 1893 (Part 4):2005
system’s modal displacement at the N— Number of locations of lumped weight
location where the secondary system is
r— Radius of circular ratl foundation
connected
0
R— Response reduction factor
Peak response quantity due to closely
spaced modes s
-—— Spectral acceleration coefficient for
Cross-modal correlation co-efficient g rock and soil sites
Modal damping ratio T, — Characteristic length of pile
@j
Frequency ratio = ~ w, — Weight lumped at ith location with the
weights applied simultaneously with
Absolute value of qua~tity inmode k
the force applied horizontally
Peak response due to all modes
w, — Total weight of the structure
considered
including weight .of liningandcontents
Maximum value of deflection above the base
Circular frequency, in rad/see, in ith z— Zone factor
mode
i5i— Lateral static deflection under its own
Response quantity in mode i, j, k lumped weight atith location (chimney
respectively weight lumped at 10or more locations)
Maximum value of deflection inX, Y, v— Poisson’s ratio of soil
Z direction respectively
0’, — Modulus of sub grade reaction of soil
5.2 Symbols and notations applicable to Section 2 in horizontal direction
are defined as under:
6 GENERAL PRINCIPLES
A— Area of cross-section atthe base of the
structural shell 6.1 Ground Motion
Ah — Design horizontal seismic coefficient 6.1.1 The characteristics (intensity, duration, etc) of
seismic ground vibrations expected at any location
CT — Coefficient depending upon the
depends upon the magnitude of earthquake, its depth
slenderness ratio of the structure
offocus, distance from the epicentre, characteristics
c“ — Coefficient ofshearforcedepending on of the path through which the seismic waves travel,
slenderness ratio, k and the soil strata on which the structure stands. The

random earthquake ground motions, which cause the
d— Thickness of pile cap o r rafl structures to vibrate, can be resolved in any three
D Maximum lateral deflection mutually perpendicular directions. The predominant
Max —
direction of ground vibration ishorizontal.
Dvj D,m — Distribution factors for shear and
moment respectively at a distance X Earthquake generated vertical inertia forces are to be
from the top considered indesign unless checked and proven to be
not significant. Vertical acceleration should be
E— Modulus of elasticity of pile material
considered in structures with large spans, those in
E< -— Modulus ofelasticity of material ofthe which stability isa criterion for design, w-for overall
structural shell stability analysis of structures. Reduction in gravity
force due to vertical component of ground motions
g— Acceleration due to gravity
can be particularly detrimental incases of prestressed
G— Shear modulus of soil = pV,2 horizontal members and of cantilevered members.
Hence, special attention should be paid to the effect
v, — Shear wave velocity of the medium
of vertical component of the ground motion on
h— Height of structure above the base prestressed or cantilevered beams, girders and slabs.
h— Height of centre of gravity of structure
6.1.2 Theresponse ofastructure toground vibrations
above base
is a function of the nature of foundations, soil,
[— Importance factor materials, form, size and mode of construction of
structures; and the duration and characteristics of
l— Moment of inertia of pile section
,), ground motion. This standard specifies design forces
n— Number of piles for structures standing on rocks or soiIs,which do not
3
IS 1893(Part 4):2005
settle, liquify or slide due to loss of strength during analysisunlessamoredefinite valueisavailable
vibrations. for use in such condition (see IS 456, IS 800
and IS 1343).
6.1.3 Thedesign approach adopted in this standard
isto ensure that structures possess minimum strength
SECTION 1 INDUSTRIAL STRUCTURES
to withstand minor earthquakes (< DBE) which occur
frequently, without damage; resist moderate 7DESIGN CRITERIA
earthquakes (DBE) without significant structural
damage though some non-structural damage may 7.1Categorization of Structures
occur; and withstand a major earthquake (MCE)
To perform well in an earthquake, the industrial
without collapse. Actual forces that appear on
structure should possess adequate strength, stiffness,
structures during earthquakes are much greater than
and ductility. Generally structures have large
the design forces specified inthis standard. However,
capacities of energy absorption in its inelastic region.
clucti[ity,arising from inelastic material behaviour and
Structures which are detailed as per IS 13920 or
detailing, andoverstrength, arising fromtheadditional
SP 6 (6) and equipment which are made of ductile
reserve strength instructures overandabovethedesign
materials~art withstand earthquakes many fold higher
strength, are relied upon to account forthis difference
thanthe design spectra without collapse; and damage
in actual and design lateral loads.
in such cases isrestricted to cracking only.
Reinforced and prestressed concrete members shallbe
Structures are classified into the following four
suitably designed to ensure that premature failure due
categories:
to shear or bond does not occur, subject to the
provisions of IS 456 and IS 1343. Provisions for a) Category 1 : Structures whose failure can
appropriate ductile detailing of reinforced concrete cause conditions that -can lead
members are given in 1S13920. directly orindirectly toextensive
10ssoflife/property topopulation
In steel structures, members and their connections
at large inthe areas adjacent to
should be so proportioned that high ductility is
the plant complex.
obtained, as specified inSP6(6), avoiding premature
failure due to elastic or inelastic buckling of anytype. b) Category 2 : Structures whose failure can
cause conditions that can lead
6.1.4 The design force specified inthisstandard shall
directly or indirectly to serious
be considered in-each of the two principal horizontal
fire hazard/extensive damage
directions of the structure and in vertical direction.
within the plant complex.
6.1.5 Equipment and other systems, which are Structures, which are required to
supported atvarious floor levelsofthe structure, shall handleemergencies immediately
be subjected to motions correspo nding to vibration at after an earthquake, are also
their support points. in importan t cases, it may be included.
necessary to obtain floor response spectra for analysis
c) Category 3 : Structures whose failure,
and design of equipment.
although expensive, does not
6.2 Assumptions leadto serious hazardwithin the
plant complex.
The following assumptions shall be made in the
earthquake resistant design of structures: d) Category 4 : All other structures.
a) Earthquake causes impulsive ground motions,
Typical categorization of industrial structures isgiven
which are complex and irregular in character,
inTable 5 .
changing in period and amplitude each lasting
for a small duration. Therefore, resonance of NOTE — The term failure usedinthedefinition ofcategories
implies lossoffunction andnotcomplete collapse. Pressurized
the type as visualized under steady-state
equipment where cracking can lead to rupture may be
sinusoidal excitations,willnotoccur,as~would
categorized bytheconsequences ofrupture.
need titne to build up such amplitudes.
7.2 Design Loads
NOTE — ~xccptionarle,sonance-likceonditionhsavebeen
seentooccurbetween longdistancewavesandtallstructures 7.2.1 Dead Load (DL)
tbunded ondeepsoftsoils.
b) Earthquake isnotlikelytooccursimultaneously These shall betaken asper IS 875 (Part 1).
with maximum wind or maximum -flood or
7.2.2 Super imposed Dead Loads (SIDL)
maximum sea waves.
c) Tbe value of elastic modulus of materials, Industrial structures contain several equipment and
wherever required, may be taken as for static associated auxiliaries and accessories that are
4
IS 1893 (Part 4):2005
permanently mounted on the structures. These loads response duetoearthquake force (EL) isthemaximum
shall be taken as per equipment specifications. of the following cases:
7.2.3 Imposed Loads (IL) +ELX & 0.3 ELY =t 0.3 ELZ
r
These shall be taken as per 1S87’5(Part 2). EL= * EL, + 0.3 ELX + 0.3 ELZ
7.2.4 Earthquake Loaak (EL) ~+ ELZ + 0.3 ELX * 0.3 EL,
The earthquake load on the different members of a where x and y are two orthogonal directions and z is
structure shall be determined by carrying out analysis the vertical direction.
following the procedure described in 10 using the
7.3.2.2 As an alternative to the procedure in 7.3.2.1,
design spectra specified in 8. Earthquake loads in x
the response (EL) due to the combined effect of the
and y (horizontal) directions are denoted by EL, and
three components can be obtained on the square root
ELY and earthquake loads in vertical direction are
of the sum of the squares (SIMS’)basis, that is
denoted by ELZ.
7.3 Load Combinations EL = (ELK)2+(ELY)2+(ELZ)2
When earthquake-forces areconsidered onastructure,
NOTE — Thecombinatiopnrocedureosf7.3.2.1and7.3.2.2
theresponse quantities duetodead load(DL), imposed applytothesameresponsequantity (say, moment inacoIumn
load(lL), super imposed dead loads(SIDL) anddesign aboutitsmajor axis, orstoreyshearinaframe) duetodifferent
earthquake load (EL) shall be combined as per 7.3.1 components oftheground motion. These combinations arcto
and 7.3.2. The factors defined in 7.3.1 and 7.3.2 are bemade atthemember forcektress Iev-ets.
applicable for Category 1to 4 structures only under 7.3.3 For structures under Category 1, which are
DBE (see 7.5). designed under MCE (see 7.5.1) and checked under
DBE, all load factors in combination with MCE shall
7.3.1 Load Factors for Plastic Design of Steel
be taken as unity.
Structures
7.4 Increase in Permissible Stresses
In the plastic design of steel structures, the following
load combinations shall be accounted for:
7.4.1 Increase in Permissible Stresses in Materials
a) 1.7(DL +SIDL +IL),
When earthquake forces are considered along with
b) 1.7(DL +S/DL) + EL, and
other normal design forces, the permissible stresses in
c) 1.3(DL +SIDL +IL +EL). material, in the elastic method of design, may be
increased by one-third. However, for steels having a
NOTE — Imposed load (ff,) in load combination shall not
include erection loadsandcrane payload, definite yield stress, the stress be limited to the yield
stress,forsteelswithout adefinite yieldpoint,thestress
7.3.2 Partial Safety Factors for L imit State Design of
will be limited to 80 percent of the ultimate strength
Rcirrfor-ced Concrete and Prestre ssed Concrete
or 0.2 percent proof stress, whichever issmaller; and
Structures
thatinpre-stressed concrete members, thetensile stress
Inthe limit state design of reinforced and prestressed intheextreme fibers oftheconcrete may be permitted
concrete structures, the following load combinations soasnottoexceedtwo-thirds ofthemodulus ofrupture
shall be accounted -for: of concrete.
a) 1.5(DL +SIDL + IL), 7.4.2 Increase in Allowable Pressures in Soils
b) 1.2(DL +SIDL +IL +EL),
When earthquake forces are included, the allowable
c) 1.5(DL +SIDL * EL), and bearing pressure in soils shall be increased as per
d) 0.9 (DL +SIDL) + 1.5 EL. Table 1,depending upon type of foundation of the
structure and the type of soil.
NOTE — Imposed load (/[.) in load combination shall not
include erection load and crane payload,
In soil deposits consisting of submerged loose sands
7.3.2.1 When responses from the three earthquake and soils falling under classification SP with standard
components are to be considered, the response due to penetration Nvalues lessthan 15inseism”iczones III,
each component may be combined using the IV,Vand lessthan 10inseismic zone 11,the vibration
assumption that when the maximum response from -caused by earthquake may cause liquefaction or
one component occurs, the responses from the other excessive total and differential settlements. Such sites
two components are 30 percent of the corresponding should preferably be avoided while locating new
maximum. All possible combinations of the three settlements or important projects. Otherwise, this

components (ELX, EL and EL,) including variations aspect of the problem needs to be investigated and
insign (plus or minus\ shall beconsidered. Thus, the appropriate methods of compaction or stabilization
5