IS 13827 : 1993(Reaffirmed 2003)

Edition 1.2(2002-04)

Indian Standard

IMPROVING EARTHQUAKE RESISTANCE OF EARTHEN BUILDINGS — GUIDELINES

(Incorporating Amendment Nos. 1 & 2)

UDC 699.841 (026) : 728.61

© BIS 2004

B U R E A U O F I N D I A N S T A N D A R D SMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

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 bythe Earthquake Engineering Sectional Committee had been approved by the Civil EngineeringDivision Council.

Himalayan Naga Lushai region, Indo-Gangetic Plain, Western India and Kutch and Kathiawarregions are geologically unstable parts of the country and some devastating earthquakes of theworld have occurred there. A major part of the peninsular India has also been visited by moderateearthquakes, but these were relatively few in number and had considerably lesser intensity. It hasbeen a long felt need to rationalize the earthquake resistant design and construction of structurestaking into account seismic data from studies of these Indian earthquakes, particularly in view ofthe heavy construction programme at present all over the country. It is to serve this purpose thatIS 1893 : 1984 ‘Criteria for earthquake resistant design of structures’ was prepared. It lays downthe seismic zones, the basic seismic coefficients and other factors and criteria for variousstructures. Subsequently IS 4326 on earthquake resistant construction of buildings in seismiczones covering the selection of materials, and type of construction was prepared in 1967 andrevised in 1976 and 1993. But nothing had so far been done to cover earthen buildings. Realisingthat about 50 percent of all housing in India consists of earthen walls and seeking their poorperformance in Himachal and North Bihar earthquakes, it was decided to prepare guidelines forimproving earthquake resistance construction of such buildings.

In preparing this standard, considerable assistance has been derived from the ‘Guidelines forEarthquake Resistant Non-Engineered Construction’, as published by the InternationalAssociation for Earthquake Engineering, in October 1986 reflecting present internationalexperience and opinion on the subject. This standard should be read in conjunction with IS 1893 :1984.

The Sectional Committee responsible for the preparation of this standard has taken intoconsideration the views of all who are interested in this field and has related the standard to theprevailing practices in the country. Due weightage has also been given to the need forinternational co-ordination among the standards and practices prevailing in different countries ofthe world.

The Committee responsible for the preparation of this standard is given at Annex B.

This edition 1.2 incorporates Amendment No. 1 (October 1995) and Amendment No. 2(April 2002). Side bar indicates modification of the text as the result of incorporation of theamendments.

IS 13827 : 1993

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Indian Standard

IMPROVING EARTHQUAKE RESISTANCE OF EARTHEN BUILDINGS — GUIDELINES

1 SCOPE

1.1 The guidelines covered in this standarddeal with the design and construction aspectsfor improving earthquake resistance of earthenhouses, without the use of stabilizers, such ascement, lime, asphalt, admixtures, etc.

1.2 The provisions of this standard areapplicable to all seismic zones ( see IS 1893 :1984 for seismic zones ).

NOTES

1 Earthen buildings are inherently weak against waterand earthquakes, and should preferably be avoided inflood prone, high rainfall areas and seismic zones IVand V.

2 Attention is hereby drawn to the fact that earthenconstruction as dealt with herein will neither qualify asengineered construction nor totally free from collapse insevere seismic intensities VIII and IX on MMI1) scale.However, inclusion of special design and constructionfeatures as recommended in this standard will raisetheir weather and seismic resistance appreciablyreducing greatly the chances of collapse even in suchseismic intensities.

2 REFERENCES

The following Indian Standards are thenecessary adjuncts to this standard:

3 TERMINOLOGY

3.0 For the purposes of this standard, thefollowing definitions shall apply.3.1 Earthen houses will include thoseconstructed using clay mud lumps, unburntclay brick or block (adobe), compacted soil inwood forms, etc, without using stabilizers.3.2 Adobe

Sun dried clay blocks or clay bricks.

3.3 Box System

A bearing wall structure without a space frame,the horizontal forces being resisted by the wallsacting as shear walls.3.4 Band

A reinforced concrete or reinforced brick orwooden runner provided horizontally in thewalls to tie them together and to imparthorizontal bending strength in them.3.5 Seismic Zone and Seismic Coefficient

The seismic zones II to V as classified and thecorresponding zone factors as specified in 6.4.2(Table 2) of IS 1893 (Part 1).3.6 Zone Factor (Z)

It is a factor to obtain the design spectrumdepending on the perceived maximum seismicrisk characterized by maximum consideredearthquake (MCE) in the zone in which thestructure is located.

4 GENERAL CONSIDERATIONS

4.1 For the safety of earthen houses,appropriate precautions must be taken againstthe actions of rain and flood waters andearthquakes. Minimum precautions arerecommended in this standard.4.2 Whereas dry clay block is hard and strongin compression and shear, water penetrationwill make it soft and weak, the reduction instrength could be as high as 80 to 90 percent.Hence, once built, ingress of moisture in thewalls must be prevented by the protection, roofprojection and waterproof mud plastering.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-stabilizedcompacted clay blocks or cement-stabilizedsandy soil blocks may be used with compatiblestronger mortars.4.4 Lightness

Since 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 Height

Experience in intensity areas of VIII has shownthe high vulnerability of two-storeyed houses,1)Modified Mercalli Intensity.

IS No. Title

883 : 1993 Code of practice for design ofstructural timber in building( fourth revision )

1893 : 1984 Criteria for earthquake resistantdesign of structures

2720 (Part 7) : 1980

Methods of test for soils : Part 7Determination of water content— dry density relation using lightcompaction ( second revision )

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hence only one storey construction shouldpreferably be adopted in seismic zones IVand V.4.6 Shape of Building

For better earthquake resistance, the buildingshould have a simple rectangular plan and besymmetrical, as far as possible about both theaxes. The load bearing walls should runcontinuously in both directions. Large housesmay have an inner courtyard for light andventilation with proper drainage outlets,instead of having projections giving rise to L, Tshape plans.

5 CONSTRUCTION OF EARTHEN WALLS

5.0 Earthen walls may be constructed in thefollowing four ways.5.1 Hand-formed in layers using mud-lumps 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 ikramesh enclosures plastered with mud ( Assamtype construction ).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 SOIL

6.0 The following qualitative tests may be usedfor determining the suitability of a soil forearthen construction.6.1 Dry Strength Test

Five or six small balls of soil of approximately2 cm in diameter are made. Once they are dry

(after 48 hours), each ball is crushed betweenthe forefinger and the thumb. If they are strongenough that none of them breaks, the soil hasenough clay to be used in the adobeconstruction, provided that some control overthe mortar micro-fissures caused by the dryingprocess is exercised ( see Fig. 1 ).

NOTE — If some of the balls break, the soil is notconsidered to be adequate, because it does not haveenough clay and should be discarded.

6.2 Fissure Control Test

At least eight folded units are made withmortars made with mixtures in differentproportions of soil and coarse sand. It isrecommended that the proportion of soil tocoarse sand vary between 1 : 0 and 1 : 3 involume. The unit having the least content ofcoarse sand which, when opened after 48 hours,does not show visible fissures in the mortar,will indicate the most adequate proportion ofsoil/sand for adobe constructions, giving thehighest strength.6.3 Strength Test of Adobe

The strength of adobe may be qualitativelyascertained 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 ( seeFig. 2 ). If it breaks, more clay and fibrousmaterial 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 1.2 N/mm2 will be desirable.

7 HAND-F ORMED LAYERED CONSTRUCTION

7.1 Walls built by hand-forming are the mostprimitive and weakest of all earthen walls,since enough moisture for full dispersion of clayis not usually employed, yet fissures alsodevelop horizontally and vertically. Use ofstraw is recommended in the clay, so as toimpart strength and reduction of fissures.

FIG. 1 DRY BALL STRENGTH TEST FOR SOIL

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7.2 The quality of construction will improve ifthe clay-water-straw mixture was allowed torest for 7 days (minimum 3 days) before use inwalls so that thorough dispersion of moisture inclay 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 BLOCK OR ADOBE CONSTRUCTION

8.1 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:

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 beallowed to rest for 7 days (minimum 3 days)before use. The lower layer of adobes should bemoistened before the ‘mortar’ is laid. Also, thesurface of the adobes to be laid should bemoistened for a few minutes before the adobe is

laid. If the mortar is seen to fissure on drying,some sand could be added to the mixture, asindicated by the ‘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 level,

b) the vertical joints should be brokenbetween the consecutive courses byoverlap of adobes and should be fully filledwith mortar ( see Fig. 3 ), and

c) the perpendicular joints between wallsshould be made in such a way thatthrough vertical joint is avoided ( seeFig. 3 ).

9 RAMMED EARTH CONSTRUCTION

9.0 Rammed earth construction is also knownas ‘Pise’ or ‘Tapial’ construction in somecountries.

9.1 To construct walls, in this method, most soilis poured in long wooden forms of the walls andcompacted to achieve the desired density. Thesoil suitable for rammed earth construction willgenerally have less clay than that used formaking adobes. The moisture content should bekept less but close to optimum moisture contentdetermined by Proctor Compaction Test [ seeIS 2720 (Part 7) : 1980 ].

9.2 To control shrinkage fissures on drying,prior testing may be required for determiningthe quantity of sand to be added to the clayeysoil, based on the moisture, the layering andthe amount 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 way

FIG. 2 FIELD TESTING OF ADOBE STRENGTH

Rectangular : 380 mm × 250 mm × 110 mm (Overlap of about 125 mm)

Square : 380 mm × 380 mm × 110 mm (Overlap of about 190 mm)

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may 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:

‘50 strokes per 1 000 cm2 of wall area using awooden 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 forfissure control.

10 RECOMMENDATIONS FOR SEISMIC AREAS

10.1 Walls

10.1.1 The height of the adobe building shouldbe restricted to one storey plus attic only inseismic zones V and IV and to two storeys inother zones. Important building (I ≥ 1.5) shouldnot be constructed with earthen walls inseismic zones IV and V and restricted to onlyone storey in seismic other zones.

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 t2/h where h is the heightof wall ( see Fig. 4 ).10.1.3 When a longer wall is required, the wallsshould be strengthened by intermediatevertical buttresses ( 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 percent the totalwall length in seismic zone V and 40 percent inzones IV and III and 50 percent in zone II.10.1.8 The bearing length (embedment) oflintels on each side of an opening should not beless than 300 mm. For an adequate configurationfor an earthen house, see 10.5.10.1.9 Hand-formed walls could preferably bemade tapering upwards keeping the minimumthickness 300 mm at top and increasing it witha batter of 1 : 12 at bottom ( see Fig. 4b ).

FIG. 3 TYPICAL BOND DETAILS IN ADOBE WALL

3313---

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10.1.10 Providing outside pillasters at allcorners and junctions of walls arerecommended as these increase the seismicstability of the buildings a great deal ( seeFig. 5 ).10.1.11 Special seismic strengthening featurersmay be done as specified in 11.10.2 House Site10.2.1 Sites with sandy loose soils, poorlycompacted clays, and fill materials shouldgenerally be discarded due to their excessivesettlements during seismic vibrations. Also,sites with very high water table should beavoided. These recommendations areparticularly important for seismic zones Vand IV.10.2.2 Site shall be above high flood level or theground shall be raised to this effect.

10.3 Foundation

10.3.1 Width of strip footings of the walls maybe kept as follows:

10.3.2 The depth of foundation below existingground level should at least be 400 mm.

FIG. 4 WALL DIMENSIONS

FIG. 5 WALL DIMENSIONS, PILLASTERS AT CORNERS

i) One storey on firm soil— Equal to wallthickness

ii) 1.5 or 2 storeys on firm soil

— 1.5 times thewall thickness

iii) One storey on soft soil — 1.5 times thewall thickness

iv) 1.5 or 2 storeys on soft soil

— 2 times the wallthickness

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10.3.3 The 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 : gravel as 1 : 4 : 8.

10.3.4 Plinth Masonry

The 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 awater-proofing layer in the form of waterproofmud ( see 13.3 ) or heavy black polythene orpolyethylene sheet at the plinth level beforestarting the construction of superstructurewall. If adobe itself is used for plinthconstruction, the outside face of plinth shouldbe protected against damage by water bysuitable facia or plaster. A water drain shouldbe made slightly away from the wall to save itfrom seepage.

10.4 Roof

10.4.1 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 be oflight material, like sheeting of any type. Heavyroofs consisting of wood joists and earthtopping are dangerous and should not be usedin Zones V and IV. Tiled and slate roofs are alsoheavier and shall be avoided in zones V and 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 ).

10.5 Adequate Configuration

Summarizing most of the recommendationscontained in this standard, a configuration isshown in Fig. 8 which will, in general, beadequate for seismic areas including zone Vand IV. Additional seismic strengtheningfeatures are presented in 12.

11 SEISMIC STRENGTHENING OF BEARING WALL BUILDINGS

11.1 Collar Beam or Horizontal Band

Two horizontal continuous reinforcing andbinding beams or bands should be placed, onecoinciding with lintels of door and windowopening, and the other just below the roof in allwalls in seismic zones III, IV and V. Only onesuch band either below the roof or at the lintellevel may be used in zone II. Proper connectionof ties placed at right angles at the corners andjunctions of walls should be ensured. Where theheight of wall is not more than 2.5 m, the lintelband can be avoided, but the lintels should beconnected to the roof band ( see 11.2 ). Thebands could be in the following forms:

a) Unfinished rough cut or sawn (70 ×150 mm in section) lumber in single piecesprovided diagonal members for bracing atcorners ( see Fig. 9a ).

b) Unfinished rough cut or sawn (50 ×100 mm or 70 × 70 mm in section) lumbertwo pieces in parallel with halved joints atcorners and junctions of walls placed inparallel ( see Fig. 9b ).

In each case, the lengthening joint in theelements shall be made using iron-straps withsufficient nails/screws to ensuire the strengthof the original lumber at the joint.

FIG. 6 FIXING WOOD RAFTER TO WALL PLATE

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FIG. 7 REINFORCING LINTEL UNDER FLOOR BEAM

FIG. 8 ADEQUATE CONFIGURATION OF EARTHEN BUILDING

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11.2 Pillasters and Buttresses

Where 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 the collar beam.

11.3 Vertical Reinforcement in Walls

In seismic zone V, mesh form of reinforcing isrecommended. Here the whole walls arereinforced by a mesh of canes or bamboos asshown in Fig. 11 along with the collar beamswhich may in this case be made from canes orbamboos themselves. The vertical canes mustbe tied to the horizontal canes as well as thecollar beam at lintel and the roof beam at eavelevel ( see 11.1 ).

12 EARTHEN CONSTRUCTIONS WITH WOOD OR CANE STRUCTURES

12.1 The scheme of earthen construction usingstructural framework of wood or cane, as shownin Fig. 12, consists of vertical posts andhorizontal 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 12.2.1 to 12.2.6, should be observed.

FIG. 9 WOODEN BAND IN WALLS AT LINTEL AND ROOF LEVELS

FIG. 10 ROOF BAND ON PILLASTERED WALLS

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12.2.1 Good connections between the wood orcane elements, so as to ensure an integralbehaviour of the structure. The connections arenormally fixed with nails. Their number anddimensions should be enough but not excessiveso as to split the elements. The connections canalso be tied with wires, ropes, leatherstraps,etc.

12.2.2 Preservation of the wood or caneelements by charring the surface or paintingwith coal tar, especially in the part embeddedin the foundation, 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 ×50 mm or 25 × 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.

FIG. 11 REINFORCEMENT IN EARTHEN WALLS

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12.3 Bracing and Braced Frames

For achieving adequate seismic resistance inZones V and IV, it will be desirable to providediagonal bracing members in the planes ofwalls as well as horizontally at the top level ofwalls. This can be done by using canes orbamboos nailed to the framing members at theends and intermediate points of intersection,before fixing the panel meshes and applyingplaster to them ( see Fig. 13 ).

Schemes for providing internal bracing systemsin earthern houses, holdfast to the walls andother alternatives are explained in Annex A.

13 PLASTERING AND PAINTING

13.0 The purpose of plastering and painting isto give protection and durability to the wallsand thatch 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, thuspreventing the occurrence of fissures during thedrying process. The second and last layer ismade with fine mud which when dried, shouldbe rubbed with 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 80/100 grade and kerosene oil in theratio 5 : 1. For 1.8 kg cut-back, 1.5 kgbitumen is melted and is poured in acontainer having 300 millilitres kerosene oil,with constant stirring, till complete mixing.This mixture can now be mixed with 30 litresof mud mortar to make it both, waterrepellent and fire resistant.’

FIG. 12 EARTHEN CONSTRUCTION WITH CANES, BAMBOO OR WOODEN STRUCTURE

FIG. 13 DIAGONAL BRACING

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13.3 For improving water and fire resistance ofthatch roof, the water proof plaster may beapplied on top surfaces of the thatch, 20 to25 mm thick, and allowed to dry. It may thenbe coated twice with a wet mixture of cowdungand waterproof plaster in the ratio of 1 : 1, and

allowed to dry again.13.4 The exterior of walls after plastering andthatch roof after treatment as explained in 13.3may be suitably painted using a water-insoluble paint or washed with water solutionsof lime or cement or gypsum.

ANNEX A( Clause 12.3 )

INTERNAL BRACING IN EARTHEN HOUSES

A-1 INTERNAL BRACING SYSTEM

A-1.1 Earthen houses are intrinsically veryweak under lateral load, hence require veryspecial techniques to make them collapse proofin seismic 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 the eventwhen the weak walls give way partially. Theframes will also restrain the walls fromdisintegrating completely.A-1.2 In using the method described in A-1.1,the following three systems can be adopted:

a) System 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 bed roomside). Such a frame will have theadvantage of redundancy, and use of lessnumber of columns. But the frame can besubjected to torsional stresses under theearthquake motions.

b) System 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 the innerwall either way. This system will have theadvantage of permitting any plan shapewithout the problem of torsion of the

frames and much greater safety of crosswalls. It will, however, consume moretimber since all frames on the inner wallswill be doubled.

c) 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 theadvantages of both A and B systems andcan be adopted for the more importantbuildings such as those built forcommunity services.As a general guidance, system A may beadopted for near symmetrical plans andsystem B for general unsymmetricalplans.

A-2 HOLDFASTS TO THE WALLS

The earthen walls may be kept no more than400 mm thick. To improve their behaviour,steel holdfasts of Z-shape may be screwed tothe wooden posts at least one for each triangleand be built into the cladding earthen wall.

A-3 OTHER ALTERNATIVES AND APPLICATIONS

A-3.1 As an alternative to wooden frames, steelpipe or angle iron frames of equal strength maybe used.

A-3.2 The internal bracing system will also beappropriately suitable for the seismic safety ofrandom rubble or brick work in mud mortarconstructions.

A-3.3 Such frames could also be inserted inexisting low strength masonry houses forretrofitting them against collapse in futureearthquakes.

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FIG. 14 BRACED WOOD FRAME FOR ADOBE AND OTHER WALLS IN MUD MORTAR

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ANNEX B( Foreword )

COMMITTEE COMPOSITION

Earthquake Engineering Sectional Committee, CED 39Chairman

DR A. S. ARYA72/6 Civil Lines, Roorkee

Members Representing

SHRI O. P. AGGARWALSHRI G. SHARAN ( Alternate )

Indian Roads Congress, New Delhi

DR K. G. BHATIADR C. KAMESHWARA RAO ( Alternate I )SHRI A. K. SINGH ( Alternate II )

Bharat Heavy Electricals Ltd, New Delhi

SHRI S. C. BHATIADR B. K. RASTOGI ( Alternate )

National Geophysical Research Institute (CSIR), Hyderabad

DR A. R. CHANDRASEKARANDR BRIJESH CHANDRA ( Alternate I )DR B. V. K. LAVANIA ( Alternate II )

Department of Earthquake Engineering, University of Roorkee, Roorkee

DR S. N. CHATTERJEESHRI S. K. NAG ( Alternate )

Indian Meteorological Department, New Delhi

SHRI K. T. CHAUBALDR B. K. PAUL ( Alternate )

North Eastern Council, Shillong

DR A. V. CHUMMARDR S. K. KAUSHIK ( Alternate )

Indian Society of Earthquake Technology, Roorkee

DIRECTOR EMBANKMENT (N & W)DIRECTOR CMDD (NW & S) ( Alternate )

Central Water Commission (ERDD), New Delhi

DIRECTOR STANDARDS (B & S), RDSOJOINT DIRECTOR STANDARDS (B & S) CB-I,

RDSO, LUCKNOW ( Alternate )

Railway Board, Ministry of Railways

MISS E. DIVATIASHRI C. R. VENKATESHA ( Alternate )

National Hydro-Electric Power Corporation Ltd, New Delhi

SHRI I. D. GUPTASHRI J. G. PADALE ( Alternate )

Central Water & Power Research Station, Pune

SHRI V. K. KULKARNISHRI P. C. KOTESWARA RAO ( Alternate )

Department of Atomic Energy, Bombay

SHRI V. KUMARSHRI R. S. BAJAJ ( Alternate )

National Thermal Power Corporation Ltd, New Delhi

SHRI M. Z. KURIENSHRI K. V. SUBRAMANIAN ( Alternate )

Tata Consulting Engineers, Bombay

SHRI A. K. LALSHRI T. R. BHATIA ( Alternate )

National Buildings Organization, New Delhi

SHRI S. K. MITTAL Central Building Research Institute, RoorkeeSHRI S. S. NARANG Central Water Commission (CMDD), New DelhiSHRI A. D. NARIAN

SHRI O. P. AGGARWAL ( Alternate )Ministry of Transport, Department of Surface Transport (Roads Wing),

New DelhiSHRI P. L. NARULA

SHRI A. K. SRIVASTAVA ( Alternate )Geological Survey of India, Calcutta

RESEARCH OFFICER Irrigation Department, Govt of Maharashtra, NasikDR D. SENGUPTA

SHRI R. K. GROVER ( Alternate )Engineers India Ltd, New Delhi

DR. R. D. SHARMASHRI U. S. P. VERMA ( Alternate )

Nuclear Power Corporation, Bombay

COL R. K. SINGHLT-COL B. D. BHATTOPADHYAYA ( Alternate )

Engineer-in-Chief’s Branch, Army Headquarters, New Delhi

DR P. SRINIVASULUDR N. LAKSHMANAN ( Alternate )

Structural Engineering Research Centre (CSIR), Madras

SUPERINTENDING ENGINEER (D)EXECUTIVE ENGINEER (D) II ( Alternate )

Central Public Works Department, New Delhi

DR A. N. TANDON In personal capacity ( B-7/50 Safdarjung Development Area, New Delhi )SHRI Y. R. TANEJA,

Director (Civ Engg)Director General, BIS ( Ex-officio Member )

Member SecretarySHRI S. S. SETHI

Director (Civ Engg), BIS( Continued on page 14 )

IS 13827 : 1993

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( Continued from page 13 )

Earthquake Resistant Construction Subcommittee, CED 39 : 1

Convener Representing

DR. A. S. ARYA In personal capacity ( 72/6 Civil Lines, Roorkee )

Members

SHRI N. K. BHATTACHARYA Engineer-in-Chief’s Branch, New DelhiSHRI B. K. CHAKRABORTY

SHRI D. P. SINGH ( Alternate )Housing and Urban Development Corporation, New Delhi

SHRI D. N. GHOSAL North Eastern Council, ShillongDR SUDHIR K. JAIN Indian Institute of Technology, Kanpur

DR A. S. R. SAI ( Alternate )SHRI M. P. JAISINGH Central Buildings Research Institute, RoorkeeJOINT DIRECTOR STANDARDS (B & S) CB-I

ASSTT DIRECTOR (B & S) CB-I ( Alternate )Railways Board, Ministry of Railways

SHRI V. KAPURSHRI V. K. KAPOOR ( Alternate )

Public Works Department, Govt of Himachal Pradesh, Shimla

SHRI M. KUNDU Hindustan Prefab Limited, New DelhiSHRI A. K. LAL

SHRI T. R. BHATIA ( Alternate )National Buildings Organization, New Delhi

DR B. C. MATHURDR (MRS) P. R. BOSE ( Alternate )

University of Roorkee, Department of Earthquake Engineering, Roorkee

SHRI G. M. SHOUNTHU Public Works Department, Jammu & KashmirDR P. SRINIVASULU

DR N. LAKSHMANAN ( Alternate )Structural Engineering Research Centre (CSIR), Madras

SHRI SUBRATA CHAKRAVARTY Public Works Department, Government of Assam, GuwahatiSUPERINTENDING ENGINEER (DESIGN) Public Works Department, Government of GujaratSUPERINTENDING SURVEYOR OF WORKS (NDZ)

SUPERINTENDING ENGINEER (D) ( Alternate )Central Public Works Department, New Delhi

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Review of Indian Standards

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This Indian Standard has been developed from Doc : No. CED 39 (5268)

Amendments Issued Since Publication

Amend No. Date of Issue

Amd. No. 1 October 1995

Amd. No. 2 April 2002

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