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IS 13827 IS 13827 Document Transcript

  • IS 13827 : I993Indian StandardlMPROVINGEARTHQUAKERESISTANCEOFEARTHENBUILDINGS-GUIDELINESUDC 699,841 ( 026 ) : 728.61o BIS 1993BUREAU OF INDIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG’NEW DELHI 110002October 1993 Price %roup 7J.( Reaffirmed 1998 )
  • Earthquake Engineering Sectional Committee, CED 39.FOREWORDThis Indian Standard was adopted by the Bureau of Indian Standards, after the draft finalized by theEarthquake Engineering -Sectional Committee had been approved by the Civil Engineering DivisionCouncil.Himalayan Naga Lushai region, Indo-Gangetic Plain, Western India and Kutch and Kathiawar regionsare geologically unstable parts of the country and some devastating earthquakes of the world haveoccurred there. A major part of 1he peninsular India has also been visited by moderate earthquakes,but these were relatively few in number and had considerably lesser intensity. It has been a long feltneed to rationalize the earthquake resistant design and construction of structures taking into accountseismic data from studies of these Indian earthquakes, particularly in view of the heavy constructionprogramme at present all over the country. It is to serve this purpose that IS 1893 : 1984 ‘Criteria forearthquake resistant design of structures’ was prepared. It lays down the seismic zones, the basicseismic coefficients and other factors and criteria for various structures. Subsequently IS 4326 onearthquake resistant construction of buildings in seismic zones covering the selection of materials, andtype of construction was prepared in 1967 and revised in 1976 and 1993. But nothing had so far beendone to cover earthen buildings. Realising that about 50 percent of all housing in India consists ofearthen walls and seeking their poor performance in Himachal and North Bihar earthquakes, it wasdecided to prepare guidelines for improving earthquake resistance construction of such buildings.1n preparing this standard, considerable assistance has been derived from the *Guidelines for Earth-quake Resistant Non-Engineered Construction’, as published by the Internatior)al Association forEarthquake Engineering, in October 1986 reflecting present international experience and opinion on thesubject. This standard should be read in conjunction with IS 1893 : 1984.The Sectional Committee responsible for the preparation of this standard has taken into considerationthe views of a11who are interested in this field and has related the standard to the prevailing practicesin the country. Due weightage has also been given to the need for international co-ordination amongthe standards and practices prevailing in different countries of the world.The Committee responsible for the preparation of this standard is given at Annex B.
  • Indian StandardIS 13827 : 1993.IMPROVINGEARTHQUAKERESISTANCBOFEARTHEN BUILDINGS-GUIDELINES1 SCOPE 3.3 Box System1.1 The guidelines covered in this standard dealwith the design and construction aspects forimproving earthquake resistance of earthenhouses, without the use of stabilizers, such ascement, lime, asphalt, admixtures, etc.A bearing wall structure without a space frame,the horizontal forces being resisted by the wallsacting as shear walls.3.4 Band1.2 The provisions of this standard are applica-ble for seismic zones III, IV and V. No specialprovisions are considered necessary in zonesI and II ( see IS 1893 : 1984 for seismic zones ).MOTES1 Earthen buildings arc inherently weak againstwater and earthquakes, and should preferably beavoided in flood prone, high rainfall areas and seis-mic zones IV and V.2 Attention is hereby drawn to the fact that eartheoconstruction has dealt with herein will neitherqualify as engineered construction nor totally freefrom collapse in severe seismic intensities VIII andEX on MMI’) scale. However, inclusion of specialdesign and construction features as recommended inthis standard will raise their weather and seismicresistance appreciably reducing greatly the chancesof collapse even in such seismic intensities.2 REFERENCESThe following Indian Standards are the neces-sary adjuncts to this standard:IS No. Title883 : 1993 Code of practice for designof structural timber in build-ing (fourth revision )1893 : 1984 Criteria for earthquakeresistant design of structures2720 Methods of test for soils :( Part 7 ) : 1980 Part 7 Determination ofwater content - dry densityrelation using light. compac-tion ( second revision )A reinforced concrete or reinforced brick orwooden runner provided horizontally in thewalls to tie them together and to impart hori-zontal bending strength in them.3.5 Seismic Zone and Seismic CoefficientThe seismic zones I to V as classified and thecorresponding basic seismic coefficient a0 asspecified in 3.4 of IS 1893 : 1984.3.6 Design Seismic Coefficient, UhThe value of horizontal seismic coefficientcomputed taking into account the soil founda-tion system and the importance factor asspecified in 3.4.2.3 (a) of. IS 1893 : 1984.4 GENERAL CONSIDERATIONS4.1 For the safety of earthen houses, appro-priate precautions must be taken against theactions of rain and flood waters and earth-quakes. Minimum precautions are recommendedin this standard.4.2 Whereas dry clay block is hard and strongin compression and shear, water penetration willmake it soft and weak, the reduction in strengthcould be as high as 80 to 90 percent. Hence,once built, ingress of moisture in the walls Mustbe prevented by the protection, roof projectionand waterproof mud plastering.3 TERMINOLOGY3.0 For the purposes of this standard, thefollowing definitions shall apply.3.1 Earthen houses will include those construc-ted using clay mud lumps, unburnt clay brick orblock ( adobe 1, compacted soil in wood forms,etc, without using stabilizers.3.2 AdobeSun dried clay blocks or clay bricks.‘)Modified Mercalli Intensity.4.3 These recommendations are low-cost and donot include the use of stabilizers, which arerather costly though effective in increasing thestrength and water-resistance of the clay unitsor walls. Where feasible time-stabilized com-pacted clay blocks or cement-stabilized sandysoil blocks may be used with compatible strongermortars.4.4 LightnessSince the earthquake force is a function ofmass, the building shall be as light as possible,consistent with structural safety and functionalrequirements. Roofs of buildings should, inparticular, be made of light weight type.4.5 HeightExperience in intensity areas of VIII has shownthe high vulnerability of two-storeyed houses,1 View slide
  • IS 13827 : 1993hence only one storey construction shouldpreferably be adopted in seismic zones IVand V.4.6 Shape of BuildingFor better earthquake resistance, the buildingshould have a simple rectangular plan and besymmetrical, as far as possible about both theaxes. The load bearing walls should run con-tinuously in both directions. Large houses mayhave an inner courtyard for light and ventilationwith proper drainage outlets, instead of havingprojections giving rise to L, T shape plans.5 CONSTRUCTION OF EARTHEN WALLS5.0 Earthen walls may be constructed in thefollowiog four ways.5.1 Hand-formed in layers using mud-!umps toform walls.5.2 Built by using sun-dried blocks or adobewhich may be cut from hardened soil, or formedin moulds, or moulded and compacted and laidin courses using clay mud as mortar.5.3 Built by using rammed earth ( Pise orTapial ) in which moist soil is filled betweenwall forms and compacted manually ormechanically.5.4 Constructed using wood, bamboo or canestructure with wood, bamboo, cane or ikra meshenclosures plastered with mud ( Assam typeconstruction ).5.5 Whereas systems 5.1, 5.2 and 5.3 depend onthe strength of earthen walls for stability, thesystem 5.4 behaves like wood frame and itsconstruction has been dealt with under 12.6 SUITABILITY OF SOIL6.0 ~The following qualitative tests may be usedfor determining the suitability of a soil forearthen construction.6.1 Dry Strength TestFive or six small balls of soil of approximately2 cm in diameter are made. Once they are dry( after 48 hours ), each bail is crushed ictweenthe forefinger and the thumb. If they are strongenough that none of them breaks, the soil hasenough clay to be used in the adobe construc-tion, provided that some control over themortar micro-fissures caused by the dryingprocess is exercised ( see Fig. 1).NOTE -- If some of the balls break, the soil I> notconsidered to be adequate, because it does not haveenough clay and should be discarded.6.2 Fissure Control TestAt least weightfolded units are made with mortarsmade with mixtures in different proportions ofsoil and coarse sand. It is recommended thatthe proportion of soil to coarse sand varq’ be-tween 1 : 0 and 1 : 3 in volume. The unit havingthe least content of coarse sand which, whenopened after 48 hours, does not show visiblefissmes in the mortar, will indicate the mostadequate proportion of soil/sand for adobeconstructions, giving the highest strength.6.3 Strength Test of AdobeThe strength of adobe may be qualita?ivelyascertained as follows:After 4 weeks of sun drying the adobe, itshould be strong enough to support inbending the weight of a person 60-70 kg( see Fig. 2 ). If it breaks, more clay andfibrous material is required to be added.6.4 Quantitatively, the compressive strengthmay be determined by testing 100 mm cubes ofclay after completely drying them. A minimumvalue of I.2 N/mm2 will be desirable.7 HAND-FORMED LAYEREDCONSTRUCTION7.1 Walls built by hand-forming are the mupstprimittve and weakest of all earthen walls, sinceenough moisture for full dispersion of clay isnot usually employed, yet fissures also develophorizontally and vertmally. Use of straw isrecommended m the clay, so as to impartstrength and reduction of fissures.(I) Making the ball (II)Crushing the bailFIG. 1 DRY BALL STRENGTH TEST FOR SOIL View slide
  • IS 138d: 1993(1) ffl.1(I) Poor strength (11) Good strengthAll dimensions in millimetres.FIG. 2 FIELD TESTING OF ADOBESTRENGTH7.2 The quality~of construction will improve ifthe clay-water-straw mixture was allowed torest for 7 days ( minimum 3 days ) before usein walls so that thorough dispersion of moisturein clay and decomposition of straw into fibrestakes place.7.3 The area of the lower layer should bemoistened well before adding the new layer soas to minimize the horizontal fissures at thejoints.8 BLOOK OR ADOBE CONSTRUCTION8.1 Suitable soil should be used for making theblocks, by using uniform size of moulds, afterkeeping the soil-water mix for 24 hours. Theblocks should be allowed to dry out of themoulds so as to allow ‘free’ shrinkage withoutdeveloping fissures.8.2 Block sizes are not standardized yet andvarious sizes are used in the country and theworld. The following sizes of blocks arerecommended for making 380 mm thick walls:Rectangular : 380 mm x 250 mm x 110 mm( Overlap of about 125 mm )Square : 380 mm x 380 mm x I10 mm( Overlap of about 190 mm )8.2.1 The square type will be better for strongerconstruction in view of less vertical jointsbetween units and better breaking of verticaljoints.8.3 The mud ‘mortar’ used to join the blockstogether should be the same soil as used inmaking blocks. However, to make it non-shrinking, straw in the ratio 1 : 1, by volume,should be mixed. The wet mix should be allowedto rest for 7 days ( minimum 3 days) before use.The lower layer of adobes should be moistenedbefore the ‘mortar’ is laid. Also, the surface ofthe adobes to be laid should be moistened for afew minutes before the adobe is laid. If themortar is seen to fissure on drying, some sandcould be added to the mixture, as indicated bythe ‘fissure control test’ in 6.2.8.4 The usual good principles of bonds inmasonry should be adopted for construction ofadobe walls, that is:a) all courses should be laid l&el,b) the vertical joints’ should be broken be-tween the consecutive courses by overlapof adobes and should be fully filled withmortar ( see Fig. 3 ), andc) the pergendicular joints between wallsshould be made in such a way thatthrough vertical joint is avoided ( seeFig. 3 ).9 RAMMED EARTH CONSTRUCTION9.0 Rammed earth construction is also knownas ‘Pise’ or ‘Tapial’ construction in somecountries.~9.1To construct walls, in this method, mostsoil is poured m long wooden forms of the wallsand compacted to achieve the desired density.The soil suitable for rammed earth constructionwill generally have less clay than that used formaking adobes. Tho moisture content should bekept less but close to optimum moisture contentdetermined by Proctor Compaction Test [ seeIS 2740 ( Part 7 ) : 1980 3.9.2 To control shrinkage fissures on drying,prior testing may be required for determiningthe quantity of sand to be added to the clayeysod, based on the moisture, the layering and theamount of compaction to be used in theconstruction.9.3 The soil should be placed in layers of about100 mm thickness and fully compacted, thenwater should be sprinkled on the compactedlayer before placing the next layer of 100 mm.The total height of this block achieved this way3
  • IS 13827 : 19932&l-+-250-I-380i-442:o80xL5UxJJUI --I-250._---III380r250r110/hz--L-1250 /250 1250 1250 c -4250 1 250~i~2501250c ,III 130 I”(I), (II) First layer (III), (IV) Second layerAll dimensions in millimetres.FIG. 3 TYPICAL BOND DETAILS IN ADOBE WALLmay be kept 500 to 800 mm. Before starting thenew block, sufficient water should be poured onthe completed layer to ensure its connectionwith the new layer.9.4 Higher compaction leads to higher strengthbut up to a limit only. Compaction should bestandardized. The following procedure isrecommended:G50strokes per 1 000 cm2 of wall area usinga wooden mallet of about 8 to 10 kg weight.’9.5 Small amount of straw, in the ratio of notmore than one-fourth of the volume of soil-water mixture, may be used in -the soil for fissurecontrol.10 RECOMMENDATIONS FOR SEISMICAREAS10.1 Walls10.1.1 The height of the adobe building shouldbe restricted to one storey plus attic only inseismic zones V and IV and to two storeys inzone III. Important building ( I > 1.5 ) shouldnot be constructed with earthen walls in seismiczones IV and V and restricted to only onestorey in seismic zone III.10.1.2 The length of a wall, between twoconsecutive walls at right angles to it, shouldnot be greater than 10 times the wall thicknesst nor greater than 64 @/Awhere Iz is the heightof wall ( see Fig. 4 ).10.1.3 When a longer wall is required, the wallsshould be strengthened by intermediate verticalbuttresses ( see Fig. 4 ).10.1.4 The height of wall should not be greaterthan 8 times its thickness ( see Fig. 4 ).10.1.5 The width of an opening should not begreater than 1.20 m ( see Fig. 5 ).10.1.6 The distance between an outside cornerand the opening should be not less than 1.20 m.10.1.7 The sum of the widths of openings in awall should not exceed 33) percent the totalwall length in seismic zone V and 40 percent inzones TV and III.10.1.8 The bearing length ( embedment ) oflintels on each side of an opening should not beless than 300 mm. For an adequate configuratlonfor an earthen house, see 10.5.10.1.9 Hand-formed walls could preferably bemade tapering upwards keeping the minimumlhlckness 300 mm at top and increasing it witha batter of 1 : 12 at bottom (see Fig. 4b ).4
  • 1 - Cross wall, 2 - Pillaster, 3 - Buttress, 1-Wall thickness(a) Walls and buttressing (b) Tapered wailAll dimensions in miilimetres.FIG. 4 WALL DIMENSIONSr-l’ ’ 1W ORv W ORVI, D51200w&loLllotx > 1200v 5 1?1;0j-x-4 l--x2I--- L-4D - Door, W - Window, V - VentilatorsAll dimensions in millimetres.FIG. 5 WALL DIMENSIONS, PILLASTERS AT CORNERS10.1.10Providing outside pillasters at ail cornersand junctions of walls are recommended asthese increase the seismic stability of thebuildings a great deal ( see Fig. 5 ).10.1.11 Special seismic strengthening featurersmay be done as specified in 11.10.2HouseSite10.2.1Sites with sandy loose soils, poorlycompacted clays, and fill materials shouldgenerally be discarded due to their excessivesettlements during seismic vibrations. Also, siteswith very high water table should be avoided.These recommendations are particularly impor-tant for seismic zones V and IV.10.2.2 Site shall be above high flood level or theground shall be raised to this effect.13821-I-2.G-3m.;I.c10.3Foundation10.3.1Width of strip footings of the walls maybe kept as follows:i) One storey on firm - Equal to wallsoil thicknessii) 1.5 or 2 storeys on - I.5 times thefirm soil wall thicknessiii) One storey on soft soil - 1.5 tim~es thewall thicknessiv) 1.5 or 2 storeys on soft - 2 times the wallsoil thickness10.3.2 The depth of foundation below existing.ground level should at least be 400 mm.5
  • IS 13827:199310.3.3The footing should preferably be built byusing stone, fired brick using cement or limemortar. Alternatively, it may be made in leancement concrete with plums ( cement : sand-:gravel : stones as 1 : 4: 6 : 10 ) or without plumsas 1 : 5 : 10. Lime could be used in place ofcement in the ratio lime : sand : gravelas 1 : 4 : 8.10.3.4 Plinth MasonryThe wall above foundation up to plinth levelshould preferably be constructed using stone orburnt bricks laid in cement or lime mortar.Clay mud mortar may be used only as a lastresort.The height of plinth should be above the floodwater line or a minimum of 300 mm aboveground level. It will be preferable to use a water-proofing layer in the form of waterproof mud( see 13.3 ) or heavy black polythene or poly-ethylene sheet at the plinth level before startingthe construction of superstructure wall. If adobeitself is used for plinth construction, the outsideface of plinth should be protected againstdamage by water by suitable facia or plaster. Awater drain should be made slightly away fromthe wall to save it from seepage.IO.4 Roof10.4.1 The roofing structure must be light, wellconnected and adequately tied to the walls.Trusses are superior to sloping roofs consistingof only rafters or A frames.10.4.2 The roof covering should preferably beof light material, like sheeting of any type.Heavy roofs consisting of wood joists and earthtopping are dangerous and should not be usedin Zones V and IV. Tiled and slate roofs arealso heavier and shall be avoided in zones Vand IV.10.4.3 If thatch is used for roof covering, itshould better be made waterproof and fire-resistant by applying waterproof mud plaster( see 13.3 ).10.4.4 The roof beams, rafters or trusses shouldpreferably be rested on longitudinal woodenelements for distributing the load on walls.10.4.5 The slopes and the overhanging willdepend on local climatic conditions. In zonessubjected to rain and snow, walls protectionmust be ensured by projecting the roof by about500 mm beyond the walls ( see Fig. 6 ).10.4.6 The roof beams or rafters should belocated to avoid their position above door orwindow lintels. Otherwise, the lintel should bereinforced by an additional lumber ( see Fig. 7 ).6I - Wooden .a11plate 2 - Overhang about 500 Ili:Il3 - Long spikes or nailsFIG. 6 FIXING WOOD RAFTERTO WALL PLVI’ELO.5 Adequate ConfigurationSummarizing most of the recommendationscontained in this standard, a configuration isshown in Fig. 8 which nill, in general, beadequate for seismic areas including zone V.nd IV. Additional seismic strengtheningFeatures arc presented in 12.II SEISMIC STRENGTHENING OFBEARING WALL BUILDINGS11.1 Collar Beam or Horizontal BandTwo horizontal continuous reinforcing andbinding beams or bands should be placed, mecoinciding with lintels of door and indowopening, and the other just below the roofinall walls in seismic zones 111, IV and V. Properconnection of ties placed at right angles at thecorners and junctions of walls should beensured. Where the height of wall is not morethan 2.5 m, the lintel band can be avoided, butthe lintels should be connected to the roof band( see 11.2 ). The bands could be in the followingforms:a)b)Unfinished rough cut or sawn ( 70 x150 mm in section.) lumber in singlepieces provided diagonal members fogbracing at corners ( see Fig, 9a ).Unfinished rough cut or sawn ( 50 x100 mm or 70 x 70 mm in section )lumber two pieces in parallel with halvedjoints at corners and junctions of wallsplaced in parallel ( see Fig. 9b ).In each case, the lengthening joint in theelements shall be made using iron-straps withsufficient nails/screws to ensuire the strength ofthe original lumber at the joint.
  • IS 13827,:19931 - Good position of beam 2 - Avoid this position 3 -- Lintel band of wood 4 - Additional lintelFIG. 7 RBINP~RCING LINTEL ~JND~~RFLOOR BEAM(a)(b)(cl1 - Light roof 2 - Light gable wall ( matting or boarding ) 3 - Rain protection overhang ( about 500 mm )4 - Stable plaster 5 -Plinth height for Rood protection G - Stable fomndation 7 - Good mortar3 - Floor level 9 - Ground level 10 - Waterproof layer(a) Building configuration, (b) Footing on firm soil, (c) Footing on soft soilAll dimensions in millimetres.FIG. 8 ADEQUATE CONFIGURATION OF EARTHEN BUILDING7
  • IS 13827 : 19931 - Adobe 2 - Mud mortar 3 - Wooden band 4 - Diagonal brace(a) Band with single timber and diagonal brace at corner (b) Band with twb timbers in parallelFIG. 9 WOODEN BANDIN WALLSAT LINTEL ANDROOF LEVELS11.2 Pillasters and ButtressesWhere pillasters or buttresses are used, asrecommended earlier at corner or T-junctions,the collar beam should cover the buttresses aswell, as shown in Fig. 10. Use of diagonal strutsat corners will further stiffen rhe collar beam.1 - Pillasters at wall junctions 2 - Two parallel timbers3 - Wood blocking at about 500 mm 4 -Diagonalbrace 5 - Integrating roof band with door/windowlintelFIG. 10 ROOF BAND ON PILLASTBREDWALLS11.3 Vertical Reinforcement in WallsIn seismic zone V, mesh form of reinforcing isrecommended. Here the whole walls are rein-forced by a mesh of canes or bamboos as shownin Fig. 11 along with the collar beams whichmay in this case be made from canes or bamboosthemselves. The vertical canes must be tied tothe horizontal canes as well as the collar beamat lintel and the roof beam at eave level( see 11.1 ).12 EARTHEN CONSTRUCTIONS WITHWOOD OR CANE STRUCTURES12.1 The scheme of earthen construction usingstructural framework of wood or cane, as shownin Fig. 12, consists of vertical posts and horizon-tal blocking members of wood or largediameter canes or bamboo, the panels beingfilled with cane, bamboo or some kind of reedmatting plastered over both sides with mud.The construction could be done in situ, buildingelement-by-element or by using prefabricatedpanels.12.2 For the satisfactory behaviour of this typeof construction the following fundamental rules,given in 123.1 to 12.2.6, should be observed.8
  • IS13827i19931 - Clay mud wall 2 - Adobe 3 - Vertical cane/bamboo 4 - Horizontal crushed canes:split bambooevery 4th layer of adobe b, S = Spacing about 400 mm d = Diameter of cane/bamboo about 20 mm(a) Pattern of canes in clay mud walls (b), (c) Pattern in adobe wallsFIG. 11 REINFORCEMENT IN EARTHBN WALLS12.2.1Good connections between the wood orcane elements, so as to ensure an integralbehaviour of the structure. The connections arenormally fixed with nails. Their number anddimensians should be enough but not excessiveso as to split the elements. The connections can.also be tied with wires, ropes, leatherstraps, etc.12.2.2 Preservation of the wood or cane ele-ments ~by charring the surface or painting withcoal tar, especially in the part embedded in thefoundation, which should preferably be ofconcrete, stone or bricks laid with cement, limeor gypsum mortar.12.2.3 In houses, built as a continuous systemas in those made with pre-fabricated panels, anupper ring beam should be placed to ensure theintegral behaviour of all walls, and to distributeevenly the roofing load ( see 11.1).12.2.4 The panel filling material should consistof wood or cane mesh, over which a layer ofmud and straw ( 1 : 1 in volume ) is placed oneach face in the form of plaster. Very often, themeshes are knit in themselves and around thestructure.12.2.5 The mud filling should be placed onlyafter fixing this upper ring beam and the roof( after completing the nailing ). This will avoidfissuring caused by the strokes of the nailingoperation.12.2.6 In the case of pre-fabricated panels, theframes could have economical sections 25 x50 mm or 25 x 75 mm or larger. The connectionbetween panels is made through nails, but thewood or cane knit mesh over which the mudfilling is placed may be fixed without the use ofnails.9
  • 1 - Clay mud covering over framing 2 - Mud plaster on matting3 - Cane/bamboo/wood framing 4 - Cane/bamboo/ikra knitting(a) Elementary~on-site construction (b) Prefabricated panelsFIG. 12 EARTHBNCONSTRUCTIONWITH CANHS,BAMBOOOR WOODENSTRUCTURE12.3 Bracing and Braced FramesFor achieving adequate seismic resistance inZones V and IV, it will be desirable to providediagonal bracing members in the planes of wallsas well as horizontally at the top level of walls.This can be done by using canes or bamboosnailed to the framing members at the ends andintermediate points of intersection, before&xing the panel meshes and applying plaster tothem ( see Fig. 13 ).I - Diagonal brace2 - Mud plaster on matting3 - Cane/bamboo/wood framing4- Cane/bamboo/ikra knittingFIG. 13 DIAGONAL BRACINGSchemes for providing internal bracing systemsin earthern houses, holdfast to the walls andother alternatives are explained in Annex A.13 PLASTERING AND PAINTLNG13.0 The purpose of plastering and painting is togive protection and durability to the walls andthatch roof, in addition to obvious aestheticreasons.13.1 In dry areas, plastering based on naturaladditives could be formed in two layers. Thefirst one of about 12 to 15 mm, is a mixture ofmud and straw ( 1 : 1 in volume ), plus a naturaladditive like cowdung used to increase themoisture resistance of the mud, thus preventingthe occurrence of fissures during the dryingprocess. The second and last layer is made withfine mud which when dried, should be rubbedwith small, hard, rounded pebbles.13.2 In wet areas, the walls should be coveredwith waterproof mud plaster. To obtain this,the following procedure may be followed:Cut-back should be prepared by mixingbitumen SO/100 grade and kerosene oii in theratio 5 : 1. For 1.8 kg cut-back, I.5 kgbitumen is melted and is poured in a conta-iner having 300 millilitres kerosene oil, withconstant stirring, till complete mixing. Thismixture can now be mixed with 30 litres ofmud mortar to make it both, water repellentand fire resistant .’
  • IS 138271199.313.3 For improving water and fire resistance ofthatch roof, the water proof Plaster may beallowed to dry again,applied on top surfaces of the thatch, 20 to13.4 The exterior of walls after plastering and25 mm thick, and allowed to dry. It may then bethatch roof after treatment as explained in 13,3coated twice with a wet mixture of cowdungmay be suitably painted using,a water-insolubleand waterproof plaster in the ratio of 1 : I, andpaint or washed with water solutions of lime orcement or gypsum.ANNEX A( C’hse 12.3 )INTERNAL BRACING IN EARTHEN HOUSESA-l INTERNAL BRACING SYSTEMA-l.1 Earthen houses are intrinsically very weakunder lateral load, hence require very specialtechniques to make them collapse proof inseismic intensities VIII and IX areas such asvertical tension members as well as diagonalbraces. A scheme of using internal bracedframes in such houses is shown in Fig. 14.Calculations for single storeyed buildings withflat heavy flexible roofs ( for example, woodenbeams with clay topping ) show that even thesoft timbers ( Group C in IS 883 : 1993 ) whensuitably framed using nail joints can serve thepurpose of holding the roof in place in theevent when the weak walls give way partially.The frames will also restrain the walls fromdisintegrating completely.8-1.2 1.nusing the method described in A-1.1,the following three systems can be adopted:a)b)Systalz A - The whole building plan maybe framed as one piece and the externalwalls built keeping the wooden frame asthe inner face of external walls and theinternal walls built keeping the frame onone of its faces ( preferably on the bedroom side ). Such a frame will have theadvantage of redundancy, and use ofless number of columns. But the framecan be subjected to torsional stressesunder the earthquake motions.Systent B -- Each room may be framedindividually, thus the external walls willhave the frame only on their inner face,the internal walls will have the frames onboth faces, preventing the fall of theinner wall either way. This system willhave the advantage of permitting anyplan shape without the problem of11c>torsion of the frames and much greasessafety of cross walls. It will, however,consume more timber since all frames onthe inner walls will be doubled.System C’ - In the third system. theframes of system B may be joined acrosswalls making it a stronger whole buildingframe. Such a system will have the ad-vantages of both A and B systems andcan be adopted for the more importantbuildings such as those Wilt for CWI-munity services.As a general guidance, system A may b.zadopted for near symmetrical plans andsystem B for general unsymmetricalplans.A-2 HOLDFASTS TO THE WALLSThe earthen walls may be kept no more thsn400 mm thick. To improve their behaviour,steel holdfasts of Z-shape may be screwed TVthe wooden posts at least one for each triangleand be built into the cladding earthen wall.A-3 OTHER ALTERNATIVES ANDAPPLICATIONSA-3.1 As an alternative to wooden framss.steel pipe or angle iron frames of equal strengthmay be used.A-3.2 The internal bracmg system b,ill also beappropriately suitable for the seismic safety o,Frandom rubble or brick work in mud mor22rconstructions.A-3.3 Such frames could also be inseried inexistmg low strength masonry houses forretrofitting them against collapse in futur:earthquakes.
  • IS 13827: 1993*PLANSHOWING SYSTEM ‘A’ SHOWING SYSTEM ‘B’CORNERBRACING.tJinimunz Dimensions1 - Column 100 X5 - Strut 100 X 50SEC JION 1-lr 3mm THICKHOLOFAST(STEEL) ‘2CORNERBRACING75* or 100 4 2 - Sill 100 X 75 3 - Beam 100 X 100 or 75 4 4 -Diagonal 100 X 506- Ceiling beam 75 X 125 or 100 $ *Corner 100 X 100 7- Hold fastJoints - Use 6 gauge nails 75 mm long minimum 2 from each face through iron sheet gussets, minimum 1 mn?.thickness or straps of 2 mm thicknessAli dimensions in miHimetres.FIG. 14 HRACBD WOOD FRAMB FOR ADOBB AND OTHBR WALLS IN MUD MORTAR12
  • IS 13827; 1993ANNEX B( Foreword )COMMITTEE COMPOSITIONEarthquake Engineering Sectional Committee, CED 39ChairmanDR A. S. ARYA72/6 Civil Lines, RoorkeeMembers RepresentingS~nr 0. 1’. AQ~A~JYAL Indian Roads Congress, New DelhiSHRI G. SHaXaN ( A~lernale)DRK.G.BHATIA Bharat Heavy Electricals Ltd, New DelhiDR C. KAXESHWARA RAO ( Alternate I )SHRI A. K. SINQR ( Alternate II )SHRI S. C. BHATIA National Geophysical Research Institute ( CSIR ), HyderabadDR B. K. R~STOQI (Altcrnatc )Dn A. R. CHANDRASEEARAN Department of Earthqllake Engineering, University of Roorkee,RoorkeeDR BRIJESH CHANDRA ( Alternate I )DR Il. V. K. LAVANIA ( A1tcrnatc II )Dc S. N. CJXATTE~JEE Indian Meteorological Department, New DelhiSHBI S. K. NAP (Alternate )Sna.r K. T. CHAUBAL North Eastern Council, ShillongDR B. K. PAUL ( Alternate )Dn A. V. CHUE~MA~ Indian Society of Earthquake Technology, RoorkeeDR S. K. KAUSHIE ( Alfcrnatc )DIRECITORE~IXAN~PBNT ( N & W ) Central Water Commission ( ERDD ), New Delhi+DIRECTOR CMDD ( NW & S ) ( Altcrnatc )~I~CTO~~ ST~XNDARDS( B & S ), RDSO Railway Board, Ministry of RailwaysTOINTDIRECTOR STANDARDS (B 8~ S 1 GB-I,” -RDSO, LUCsNOW (Altcsnat; )MISS E. DIVATIASFIRI C.R.VENIXATESH~ (Alternate )San1 I. D. GIJPTASHRIJ. G. PADALE ( Alternate 1SHRI V.K.KULKARNISHRI P. C. KOTESWARA RAO (Altcrnatc)SHRI V. KWIAILSERI R. S. BAJAJ ( Alternate )SHRI M.Z. KURIENSHRI K.V. SUBRAMANIAN( Alternate)SHR1A.K. LALSHRI T. R. BHATIA (Altcrnatc)SHRI S. K. MITTALSHRI S. S. NARANCJSnnr A. D. NARI~NSHRI 0. P. ACWAXWAL ( Alternate )Sara P. L. NARUL~S&I A. K. S~rvasr~va ( Altcvzatc )RESEARCH OFFICERD~D.SENGU;PTASHRI R. K.GROVIZR ( Altcrna2c )DR R. b-. SEXMASXRI U. S. P. VEXMA ( Alternate 1COL R.K. SINQHLT-COLB.D. BIIATTOPXDRYAYA( Alternate )National Hydro-Electric Power Corporation Ltd, New DelhiCentral Water & Power Research Station, PuneDepartment of .4tomic Energy, BombayNational Thermal Power Corporation Ltd, New DelhiTata Consulting Engineers, BombayNational Buildings Organization, New DelhiCentral Building Research Institute, RoorkeeCentral Water Commission ( CMDD ), New DelhiMioistry of Transport, Department of Surface Transport ( RoadsWing ), New DelhiGeological Survey of India, CalcuttaIrrigation Department, Govt of Maharashtra, NasikEngmeers India Ltd, New DelhiNuclear Power Corporation, BombayEngineer-in-Chief’s Branch, Army Headquarters. New DelhiDrt P. SRINIX-ASULU Structural Engineering Research Centre ( CSIR ); MadrasCentral Public Works Department, New DelhiDR N.LAKSH&SANAN (Alternate)SUPERINTENDIN~ENQINEER( D)~EXECUTI~E ENQINEER(D ) II (AlternateDR A.N. TANDO:< In personal capacity ( B-7150 safdarjung Deoelopmcnt Area, .11>wDelhi )’SHRI Y. R. TANEJ.~, Director General, BIS ( Ex-oj%icioMember )Director ( Civ Engg )Member SecretarySHRI S.S.SETHIDirector ( Civ Engg ),BIS( Coatinucd on page 14 )13
  • Is 13827 : 1993( Continued from page I3 )Earthquake Resistant Construction Subcommittee, CED 39 : 1COnVenerDRA.S. ARPAMembersSHRI N.K. BHATTACHUYASERIB.K.CHAK~ABORTYSHRI D.P. SII?GII(Alternate )SHZI D. N. GHOSAL33~ SUDIIIR K. JAINDn A. S. R. Sar ( Alternate )SHBI M. P. JAISINGBJOINTDIRECTOR STANDARDS(B &S)Cl3-IASSTT DIRECTOR ( B& S )%&I (Altcrnala)SHRI V. KANJISwm V. K. K.POOR ( Ahrnate )SBRI M. KTJNDUSHIU A.K. LALSERI T. R. BIIATIA ( Alternate )DR B. C. MAT~~JRDn ( MRS ) P. R. BOSE ( Alternate )Snn~ G. M. Snoua~~uBR P. SRIXIVASULUDR N. LAKSIIJIAXM (~4Ilcmate)SELU SUBRATA CHAKI~AVA~TYSUPERINTENDINOENGINEER ( DESIGN )S~PER~NTEXDIN~~S-IJRVE~O~oI3WORKS (NDZ )SUPEBINTENTUXG EXQINXER( D)(Alterma8c).XepresentingIn personal capacity ( 7216 Civil Lines, Hoorkce)Engineer-in-Chief’s Branch, New DeihiHousing and Urban Development Corporation, New DelhiNorth Eastern Council, ShillongIndian Institute of Technology, KanpurCentral Buildings Keseacch Institute, RoorkesRailways Board, Ministry of RailwaysPublic Works Department, Govt of Himachal Praderh,~ShimlaHindustan Prefab Limited, New DelhiNational Buildings Organization, New DelhiUniversity of Roorkee, Department of Earthquake Engineering,RoorkeePublic M’orks Department, Jammu 8s KashmirStructural Engineering Research Centre ( CSIR ), kladrasPublic Works Department, Government of Assam, GuwahatiPublic Works Department, Government of GujaratCentral Public Works Department, New Delhic14
  • Standard MarkThe use of the Standard Mark is governed by the provisions of the Bureau of IndianStandards Act, 1986 and the Rules and Regulations made thereunder. The Standard Mark onproducts covered by an Indian Standard conveys the assurance that they have beenproduced to comply with the requirements of that standard under a well defined system ofinspection, testing and quality control which is devised and supervised by BIS and operatedby the producer. Standard marked products are also continuously checked by BIS for con-formity to that standard as a further safeguard. Details of conditions under which a licencefor the use of the Standard Mark may be granted to manufacturers or producers may~beobtained from the Bureau of Indian Standards.
  • B.ureao of Indian StandardsBIS is a statutory institution established under the Bureau 01 Indian Stundads Acf, 1986 tz promotebrmonious development of the activities of standardization, marking and quality certification of goodsand attending to connected matters in the country.CopyrightBIS has the copyright of all its publications. No part of these publications may be reproduced in anyform without the prior permission in writing of BIS. This does not preclude the free use, in the courseof implementing the standard. of necessary details, such as symbols and sizes, type or gradedesignations. Enquiries relating to copyright be addressed to the Director ( Publications ), BIS.Review of lndian StandardsAmendments are issued to standards as the need arises on the basis of comments. Standards are alsoreyiewed periodically; a standard along with amendments is reaffirmed when such review indicates thatno changes are needed; if the review indicates that changes are needed, it is taken up for revision.Users of Indian Standards should ascertain that they are in possession of the latest amendments oredition by referring to the latest issue of ‘BIS Handbook’ and ‘Standards Monthly Additions’.Comments on this Indian Standard may be sent to BIS giving the following reference:Dot No. CED 39 ( 5268 )Amendments Issued Since PublicationAmend No. Date of Issue.Text AffectedBUREAU OF INDIAN STANDARDSHeadquarters:Manak Bhavan, 9 Bahadur Shah Zafar Marg, New Delhi 110002Telephones : 331 01 31, 331 13 75Regional Offices ICentral : Manak Bhavan, 9 Bahadur Shah Zafar MargNEW DELHI 110002Eastern : l/14 C. I. T. Scheme VII M, V. I. P. Road, ManiktolaCALCUTTA 700054Northern s SC0 445-446, Sector 35-C, CHANDIGARH 160036Telegrams : Manaksanstha( Common to all offices )TelephoneI331 01 31331 -1375I37 84 99, 37 85 6137 86 26, 37 86 62153 38 43, 53 16 4053 ~2384Southern : C. 1. T. Campus, XVCrosr Road, MADRAS 600113I235 02 16, 235 04 42235 15 19, 235 23 15Western -r Manakalaya, E9 MIDC, Marol, Andheri ( Eaot )BOMBAY 400093632 92 95, 632 78 58632 78 91. 632 78 92Branches :lAHMADABAD. BANGALORE. BHOPAL. BHUBANESHWAR.COIMBATORE. FARIDABAD. GHAZIABAD. GUWAHATI. HYDE-RABAD.JAIPUR. KANPUR. LUCKNOW. PATNA. THIRUVANANTHAPUKAM.
  • AMENDMENT NO. 1 OCTOBER 1995TOIS 13827 : 1993 IMPROVING EARTHQUAKERESISTANCE OF EARTHEN BUILDINGS -GUIDELINES(Page1, clause 1.2) -Substitute the following for the existing clause:‘1.2 The provisions of this standard are applicablelo all seismic zones ( seeIS 1893 : 1984 for seismic zones )‘.( Page 3, clause 9.1, last~line) - Substitute ‘IS 2720 ( Part 7 ) : 1980’ for‘IS 2740 ( Part 7 ) : 1980’.. ( Page 4, clause 10.1.1,lines 4 and 7 ) - Substitute ‘other zones’ for ‘zoneIII’.c,auie?rge 4Y 1cause 10.1.7 ) - Add the following matter at the end of the‘ , and 50 percent in zonea I and II’.(Page 6, clause 11.1) - Insert the following matter after the first sentence:‘Oniy one such band either below the roof or at the lintel level may be used inzones I and II.’(CED39)Reprography Unit, BIS, New Delhi, India
  • AMENDMENT NO. 2 APRIL 2002TOIS 13827:1993 IMPROVING EARTHQUAKERESISTANCE OF EARTHEN BUILDINGS — GUIDELINES{ Page 1, clause 3.5) – Substitute the following for the existing:‘3.5 Seismic Zone and Seismic CoefficientThe seismic zones H to V as classified and the corresponding zone factors asspecified in 6.4.2 (Table 2) of IS 1893 (Part l)’.( Page 1, clause 3.6) — Substitute the following for the existing:‘3.6 Zone Factor (Z)It is a factor to obtain the design spectrum depending on the perceived maximumseismic risk characterized by maximum considered earthquake (MCE) in thezone in which the structure is located.’[ Page 4, clause 10.1.7( see also Amendment No. 1 ) ] — Substitute ‘ZoneII’for ‘zones I and II’.[ Page 6, clause 11.1 ( see also Amendment No. 1 ) ] — Substitute ‘Zone II’for ‘zones I and II’ .( CED 39 )Reprography Unit, BIS, New Delhi, India