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IS 4247-2 (1992): Code of Practice Structural Design of
Hydroelectric Power, Part 2: Superstructure [WRD 15:
Hydroelectric Power House Structures]
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Satyanarayan Gangaram Pitroda
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IS 4247 ( Part 2 ) :1992
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Indian Standard
CODE OF PRACTICE FOR
STRUCTURAL DESIGN OF SURFACE
HYDROELECTRIC POWER STATION
PART 2 SUPERSTRUCTURE
( Second Revision)
c
DIS 1992
BUREAU OF INDIAN STANDARDS
MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NBW DELHI 110002
Price Groap 3
AMENDMENT NO.1 JANUARY 2008
TO
IS 4247 (PART 2): 1992CODE OF PRACTICE FOR
STRUCTURAL DESIGN OF SURFACE HYDROELECTRIC
POWERSTATION
PAAT2SUPERSTRUCTURE
(S~co"dR~blo")
(Page 1,clause4)- SubstituteCIS4241(Part I): 1993'for'IS4241(PartI): 1984'.
(Page 1,clauseS.3) - Substitute 'IS 456 :2000'for 'IS456 : 1978'.
(Page 2, clause9.1) - Substitute 'IS456 :2000'/01' 'IS 456 : 1978'.
(Page 3, clause 10.4) - Substitute 'IS 1346 : 1991'for CIS 1346 : 1976',
and 'IS 3036 : 1992'for 'IS 3036 : 1980' respectively.
(Page 4,clause 11.3.4)- Substitute 'IS456:2000'for'IS456: 1918'.
(Page 6. clause 16.2)- Substitute 'IS 456 :2000' for 'IS456 : 1968'.
(Page6, AnnexA) - Substitute:
a) 'IS 456 :2000 Plain and reinforcedconcrete - Code ofpractice (fourth
revision)'Jar 'IS 456 : 1978 Code ofpractice for plain and reinforced
concrete(thirdrevision)'.
b) 'IS 1346 : 1991 Code of practice for water proofmg'of roofs with
bitumen felts (thirdrevision)'for 'IS 1346 : 1976 Code ofpractice for
water-proofingofroofs with bitumen felts (secondrevision)'•
c) 'IS 3036 : 1992 Code of practice for laying lime concrete for water
proofed rooffinish(secondrevision)'101''IS 3036: 1980Code ofpractice
forlayinglimeconcretefora waterproofedrooffinish(first revuion)'.
d) 'IS 3067 : 1988 Code of practice for general design details and
preparatory work for damp-proofmg and water-proofing of buildings
(second revision)' lor 'IS 3067 : 1980 Code of practice for general
design, detail and preparatoryworkfordamp-proofingand water-proofing
ofbuildings(firstrevision)'.
Amend No. I to IS 4247 (Part2) : 1992
e) 'IS 4247 (Part 1): 1993Code ofpractice for structural design ofsurface
hydroelectric powerstations: Part1Datafordesign(thirdrevision)'lor
\154247 (Part 1): 1984Codeofpractice for structural design ofsurface
hydroelectric powerstations: Part 1Data for design'.
(Page 6, Annex A) - Insert 'IS 4971 : 1968 Recommendations for
selectionofindustrialfloorfinishes''attheappropriateplace.
(WRD 15)
Rcpl'OIfaphyUni~BIS~NewDelhi~India
2
Hydroelectric Power House Structures Sectional Committee. RVD IS
FOREWORD
This Indian Standard was adopted by the Bureau of Indian Standards, after the draft finalized by
the Hydroelectric Power House Structures Sectional Committee had been approved by the River
Valley Division Council.
Preliminary design ofhydel powerstation generally consists ofstudy ofalternative schemes and cost
estimates for different site arrangements. The next stage usually involves detailed planning
consisting of comparative studies of different designs and arrangements of plants for the finally
agreed site and operating conditions. The final stage of design is normally concerned with the
structural design and building details, therefore orderly design procedure in the initial stages saves
time in the long run and avoids replanning and difficultstructural problems later OD.
Design of superstructure ofa hydro power station is an important item and requires considerable
attention. For maximum economy, judicious selection of a particular type of superstructure and
its components amongst the various types in vogue, isessential. This standard is intended to help
the designer in designingsurface hydro power station for the loads likely to come on them during
construction, erection, operation, maintenance and repair. This code of practice represents a
standard of good practice and, therefore, takes the form ofrecommendations.
This standard has been published in three parts, Part 1covers data for design while Part 3 covers
substructures.
This standard ( Part 2 ) was first published in 1968and subsequently revised in 1978. The present
revision has been made in view of the experience gained during the course oftheseyears in use
of this standard. The major modifications in this revision are in respect of design criteria.
Construction details for galvanized corrugated steel sheet roofs design ofcolumns and clause on
choice amongst various types of girders have been deleted. Also additional information regarding
floor finishes have been included.
For the purpose of deciding whether a particular requirement ofthis standard is complied with, the
final value, observed or calculated, expressing the result of a test or analysis, shall be rounded
off in accordance with IS 2 : 1960'Rules for rounding off numerical values (revised)'. The number
of significant places retained in the rounded off value should be the same as that ofthe specified
value in this standard.
, "l
I••••,.
IS 4147 (Part 2) : 1992
Indian Standard
CODE OF PRACTICE FOR
STRUCTURAL DESIGN OF SURFACE
HYDROELECTRIC POWER STATION
PART 2 SUPERSTRUCTURE
( Second Revision)
1 SCOPE 6 TYPES AND LAYOUT OF
SUPERSTRUCTURE
This standard (Part 2 ) covers types, layout and
the structural design ofsuperstructureofa surface 6.1 The superstructure of surface hydel power
hydroelectric power house. house can be, generally, classified into the
following types:
1 REFERENCES
a) Outdoor Types - The power house in
The Indian Standards listed in Annex A are which generators, exciters, etc, are provid
necessary adjuncts to this standard. ed with local steel housings for weather
protection but are otherwise fully exposed
above the intermediate structure. They
3 TERMINOLOGY
require travelling gantry cranes for the
erection and maintenance of the units.
3.0 For the purpose ofthis standard, the follow
ing definition should apply. b) Semi-outdoor Type- The power house has
a low roof or deck immediately over the
3.1 Superstructure generators. The height not being sufficient
to house the overhead travelling crane. The
The portion of power house extending from erection and maintenance of machine is
turbine floor/generator floor right up to the top done through hatches provided in the roof.
including gantry columns, roofs, walls, etc.
c) Indoor Type - This type of power house
has a superstructure high enough to
4 DESIGN
accommodate the overhead travelling
The data to be collected for the design of a crane. In this case all the erection and
surface hydro power station should be in accor maintenance of the machinery is done
dance with IS 4247 ( Part 1) : 1984. inside the building.
5 MATERIAlS:: 6.2 The factors generally influencing the choice of
the types ofsuperstructures are, site topography,
5.1 Structural Steel approach road level, tail water level, weather
conditions, type of machine, security, economy
The structural steel should conform to IS 2062 : and aesthetics.
1984 or IS 226 : 1975 and IS 8500 : 1977.
6.3 Important aspects in the layout of super
5.1 Reinforcement
structure are positioning ofgantry columns, fixing
~
to their heights and selection of suitable roofing
The reinforcement steel should conform
system. The layout ofgantry columns is affected
IS 432 (Part I ) : 1982 or IS 1786 : 1985.
to quite an extent by the transverse joints provid
ed in the substructure. Twin columns should
5.3 Concrete normally be provided at places where a joint
occurs in the substructure. The location ofgantry
The concrete should conform to IS456: 1978. columns is also influenced by the following:
Minimum M20 grade of concrete should be
used wherestructure comes in contact with water. a) Availability ofspace for foundations which
would depend upon the layout ofthe scroll
5.4 G.I'~DIzed CorruaatedSteelSbeets case and the openings in the substructure;
and
Galvanizedcorrugated steel sheets should co n"
form to IS 277: 1985~ b) The likely size ofgantry girder.
1·
IS 4247 ( Part 2) : 1992
6.3.1 The height ofcolumns should be such that 8.8 Temperature. Etreetl
the crane hook in its highest position is able to
handle the biggest machine part with other The total temperature variation in structure
machines remaining undisturbed. Also the should be considered as two-thirds of the average
clearance of hook over the erectionbay floorlevel maximumannual variation in temperature. The
should be enough for the biggestmachine part to structure should be designed to withstand stresses
+
be unloaded from the trailer. Suitable arrange consequent to half the. total temperature
ment should bemade for detanking of transfor variations.
mers but increasing the height ofmachinehall for
this reasonalone is not desirable. NOTE- The maximum annual variation for this
purpose should betaken as the difference between the
mean ofthe daily minimum temperatures during the
7 ELEMENTS OF SUPERSTRUCTURE
coldest month of a year and the mean ofthedaily
maximum temperatures during the hottest month of
7.1 The superstructure ofa powerhouse generally the year.
consists of the following elements:
8.' Special Loads
8) Roof,
Ifthe superstructure ofthe power station is to be
b) Roof supports, subjected to any other load not covered in 8.1
to 8.8 due to its special use, such as switch yard,
c) Gantry girder,
transmission cable connected to columns, etc,
d) Gantry columns, appropriate additional loads should also be
considered.
c) Beams or braces,
NOTE - The design based on the above loads (8.1
f) Panel walls, to 8.8) should also be checked for erection and
construction loads and crane testing load.
g) Floors, and
h) Auxiliary rooms and service bay and 9 STRESSES
unloading bay when they form part of
main power house. 9.1 Permissible Stresses
The permissible stresses should be taken in
8 DESIGN LOADS AND FORCES
accordance with IS 456: 1978 for concrete and
reinforcement and IS 800: 1984 for structural
8.1 Dead Loads
steel.
These should consist ofself load of the structure
Reduction in permissible stresses, if any, for
and the p~rmanent superimposed loads.
components of power house in contact with water
may be decided by the designer.
8.2 Live Loads
The liveloads for roofand floors should be taken 9.2 Increase In Permissible Stresses (or Various
in accordance with IS 875 (Part 2): 1987 Load Combinations •
respectively.
The design of superstructure should bechecked
8.3 Wind Load for the combination of loads given in Table 1
with the corresponding increase in permissible
stresses.
Wind load should be taken in accordance with
IS 875 ( Part 3) : 1987.
9.3 Fatigue Considerations
8.4 Snow load should be taken in accordance
Steelmembers and their connections subjected to
with IS 875 (Part 4) : 1987 whereverapplicable.
fluctuations ofstressesshould be designed accord
ing to permissible stressesgiven in IS 807 : 1976.
8.5 Crane Loads
The increase in permissible stresses should,
however, remain the same as given in 9.1.
Crane loads should be considered in accordance
with IS 4247 (Part 1) : 1978.
10 ROOF
8.6 Earthquake Forces
10.1 Type of Roofs
These should be considered in accordance with
IS 1893 : 1984. The roof may be galvanized corrugated steel
sheets or of reinforced concrete, precast or cast :
8.7 Water Pressure and Earth Pressure in-situ. In the case of galvanized corrugated
sheet roofthe supporting member may be a steel
Appropriate values of these forces under static truss ofa gable steelframe whereas in the case of
and dynamic conditions should be considered latter it may either be a steel truss or beam or a
where applicableas per IS 1893: 1984. reinforcedconcretebeamarch or a gableframe.
2
IS 4247 ( Part 2) : 1991
Table 1 Permillible Increase InStressel'forVariousLoad ComblaatioDS
(Clause 9.2 )
SI No. LoadCombinations Permissible
.' IncrealeInStresses
(1) (2) (3)
o
i) Dead load. Jiveload, movingcrane loaded to halfitl capacity and percent
normal tail water level
o
ii) Dead load, live load, standingcrane load to its full capacity and percent
normal tail water level
iii) Dead load, live load, moving crane loaded to halfits capacity, 25 percent
wind, temperature and normal tail water level
iv) Dead load, live load moving crane loaded to full capacity, 25percent
temperature and normal tail waterlevel
v) Dead load, live load, unloaded standing crane, temperature, 331percent
earthquake and normal annual tail water level
vi) Dead load, live load, moving crane loaded to halfits capacity, 331 percent
temperature and tail water level corresponding to design flood
vii) Dead load and temporary orconstruction loads 25percent
NOTES
1 Live loads should beas specified in IS 4241 ( Part 1) : 1984. Wind seismicand crane loads have been considered
as distinct from the live loads in the above table. While consideringearthquake, live loads may be suitably
modified in accordance with IS 1893 : 1984.
2 In case where there are some special conditions ofloading particularto a power station as specified in 8.8 other
than those mentioned in the above table, the sameshould also be accounted for appropriately.
3 For rivets, bolts, tension rods, the permissible stressesshould be increased by 2S percent only.
10.1.1 Galvanized Corrugated Sheet Roof 10.3.1 Reinforced Cement Concrete Roofing
Generally, the galvanized corrugated sheets of A minimum slope of 1 in 120should be provided
the roof are fixed on purlins supported on the for proper drainage of roof.
roof members. The gauge of the galvanized
corrugated sheet should depend on the load and 10.4 Waterproofing
the spacing ofthe purlins or else the spacing of
the purlins and rafters will have to befixedto Waterproofing of roof should be carried out in
suit a particular gauge for given design loads. accordance with the relevant Indian Standards
However, the thickness of corrugated sheet (see IS 1346: 1976, IS 3036: 1980, IS 3067 :
should be not less than 1·25 mm. 1988 and IS 4365 : 1967 ).
10.1.2 Reinforc(dConcrete Roof
II ROOF SUPPORTS
The' reinforced concrete roofcan either be precast
or cast insitu, The distance between the two 11.1 Type of Roof Supports
adjacent roofsupporting members may be, some
times too large for slab to directly span the gap.
Power house roof supports,in general are either
It maygenerally be desirable to connect the roof
of steel or concrete. In either case it should be
members either by purlins or cross members or
an integral part of a transverse frame. Its con
to use ribbed or any other suitable type of precast
nection with the upstream and downstream
slabs.
columns may generally be hinged or fixed depen
ding upon the type ofconstruction.
10.2 Choice ofthe TJpe of Roof
Th~cboiccofthe type of roof primarily depends 11.1.1 Steel
upon its use and the available construction
facilities, time available for construction and the Steel roofsupport may either be a beam fixed to
economics; the secondary consideration being the steel columns or a steel truss pin jointed to
architectural appearance. the columns. In either case the top of roof
support may be flat or sloping depending upon
10.3 Slope 01Roof the type ofcovering. In case of steel truss the
The slope of the roof should be as specified columns may either be ofsteel or concrete.
in 10.3.1 and 10.3.2.
11.1.2 Concrete'
10.3.1 Galvanized Corrugal.dSheet Roofing
Concrete roof support mayeither be an arch or
The ,slope of 'the roof should depend upon the a concrete beam fixed to the concrete columns
typooftruss to be used. Generally, a roof slope resulting in a frame. In case of beams, the top
,,may be from 1/4 to 1/10. mayeither befiat or sloping.
3
