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है”ह”ह

IS 11096 (1984): Code of practice for design andconstruction of bolt-jointed timber construction [CED 13:Building Construction Practices including Painting,Varnishing and Allied Finishing]

fS : 11096 - 1984

Indian Standard

CODE OF PRACTiCE FOR DESIGN AND CONSTRUCTION OF

BOLT JOINTED TIMBER CONSTRUCTION

Building Construction Practices Sectional Commitlcc, BDC 13

Chairman

SHRI C. P. MALIK C-4/38, Safdarjung Development Area

New Delhi 110016

Members Representing

SIIRI P. D. AQA~WAL Public Works Department, Government of Uttar Pradesh, Lucknow

Srrm Ii. K. MATILUR ( ALfemale )

Snar D. R. BATLIVALA Bhabha Atomic Research Centre, Bombay Sam B. K. CIIAKI~A~~ICTY Housing and Urban Development Corporation

Ltd, New Delhi SHllI S. M. &xl. ( AhNtt8 )

CHIEF ENQINEKIL ( Bunox ) Public Works Department, Government of Tamil Nadu

SIJP,QLINTENT~lNO IZNoINnBll ( SPI~CIAL BrJll&INo c11cc:r,r: ) ( Alternate )

CHIEF ENQINI~:~:I~-~UM-~I)~)I)ITIONAL Public Works Department, Government of SIoILn’rAL&Y ( Bli )

Est~~c:tr~~~tvr.: Exo~sxrm ( Allerrrdle ) Rajasthan, Jaipnr

cntrx L~olNnnlt ( TI<AINlNo ) Central Public Works Department, New Delhi Surnrt~~rn~ni~o ENQINrsk!ll

SH ,LI k ‘I$;;;;&r$‘)N( 4llerrlele ) Engineer-in-Chief’s Branch, Army Headquarters,

New Delhi Snnr A. v. Gl)PALl<nISnNA ( .4llernale )

~II~~!XTOI<, At<(‘JlllW:‘l ,iltb: Research, Designs and Standards Organization ( Ministry of Railways ), Lucknow

JOINT DIICBI,TOI<, AI(CHITII:(:,~IJIIE ( ill1ernate )

SlCRI s. S. GILL Public Works Department, Government of I’trnjah, Chandigarh

Srrn~ M. KAILIIICAYAN Builders’ Association of India, bornbay

( Continnued on page 2 1

0 CoPyright 1985

INDIAN STANDARDS INSTITUTION

This publication is protected under the Indian Cofyri~ht Act ( XIV of lL)i)‘/ ) and

reproduction in whole or in part by any means except with writtm permission of rhe

publisher shall be deemed to be an infringement of copyright under the said r\ct.

IS: 11096 - 1984

( Confir77ledfiom fmge 1 )

Melllbe7.S Repesetrtitq

SIIILI R. L. KCMAR Institution of Survq Ors, New Delhi SllRI c. v. PA~lwAltl,ilaN ( Altertlole )

Srrm M. Z. KUILIJGN Tata Consulting Engincrrs, Bombay Snrtr G. Ii. MAJUM~AR Hindustan Prefab Ltd, New D~~llli

Slrlll H. S. PAsn~an~ ( iil&wnte ) SHILI R. C. MANRAL Central Building Rcscarch Institute ( CSIR ),

Roorkee SIIIII .J. S. SIIAIXMA ( Alter&e )

SI~ILI B. V. B. PAI Concrete Association of India, Bombay Slrnr P. SI~INIVASAN ( filternate )

SIIilI P. K. PANI,Ai% State Bank of India, Bombay SHKI I<. S. I?~~IJ~~JII Forest Research Institute and Coll<ges, Drhra Dun SIIILI S. G. RANAnlVE Indian Institute of Architects, Bombay

Slrlrr liU.?dMY SlIl~OPF ( Alternate) Bureau of Public Enterprisq Ministry of Finance Central Road Research Institute, NI~W D(>lhi Life Insurance Corporation of India, Bombay

National Buildings Organization, New Delhi

National Buildings Construction Corporation Ltd. New Delhi

Public Works & Housing Dcpartmcnt, IIombay The Institution of Engineers ( India ), Calcutta Ministry of Shipping & ‘Transport ( Roads Wing )

Director General, IS1 ( ,%-a~& 12lemlar )

Secratary

SUM A. I<. SAINI

Assistant Director ( Civ Engg ), IS1

Timber Engineering Subcommittee, BDC 13 : ~1

SIIIGI K. S. PlrUTIII

Members

Forest Research Institute & Collcgcs, Dchrn Dun

SIII~I I<. K. P~NIIARI (.dternate to Shri I<. S. l’ruthi 1

’ SUM A. N. BAJAJ In personal capacity ( EU/117, ‘I;gore &den, .New Delhi-l 10027 )

Central Building Kcscarch Institute, 1Courkcl:

DEPUTY DwECTOli ST,kN,,A,C,,S Railway Board ( Ministry of liail\>a) Y ), New (B&S) Delhi

ASSISTANT DII~ECTOI~ ( B & S ) ( Atemate ) ( Continued err papc 19 )

2

IS : 11096 - 1984

Indian Standard

CODE OF PRACTICE FOR DESIGN AND CONSTRUCTION OF

BOLT JOINTED TIMBER CONSTRUCTION

0.1 This Indian Standard wan adopted by the Indian Standards Institution on 3 1 May 1984, after the draft finalized by the Building Cons- truction P’racticcs Sectional Committee had been approved by the Civil Engineering Division Council.

0.2 Thr prefabricated timber structures find use in defence and industrial sector due: to ease in transportation, economy and speed in execution. Bolt-.joirltcd tirnbcr construction thus befits pre-cut system of prefabriratirl# strllc.trlr:tl tiflllx:r componcn ts for semi-permanent st.ructures ( slic& ) which ;* 11’ rcqui1.C.d to lx: crccted at high altitudes and in rcmotc places.

0.7 The factors and data in this stnrldard is based on work tlo11~ ljy FKT, Ikhra I>~tn rc;i:y H~rdzoiclin Rinulu ( Ar+n ) class C ( ordir:xy group ) tim1,c.r.s wit11 milt1 stc3.l bolts havin K avcraqc yield stress of 3 15 N/rnm2. The fkctors and data can be used with other species of timber based on relevant compressive stress values.

0.4 For the put‘pose of’ deciding whether a particular requircmcnt of this stantlxrtl is cornpliccl with, the final value, observed or calculated, express- ing the result of a test or analysis, shall be rounded off in accxn-dance wit11 IS : 2-l!lGO*. l’he number of significant places retained in the rounded off value sho111d bc the sa~nc as that of the spcciii~d value in this standard.

P. SCOPE

1.1 This standard covers the design, fabrication, finishing and maintenance 01‘ bo]L jointed tirnbcr construction for structural use.

3

IS t 11096 - 1984

2. MATERIALS

2.1 Timber - Timber used for all bolt jointed timber construction shall conform to IS : 362%1966*. Normally timber seasoned to moisture contrnt as specified for building construction work in IS : 287-1973t shall be used.

2.2 Bolts and Nuts - These shall conform to the requirements of IS : 1363-1967$. To avoid rusting, use of galvanized bolts and nuts is recommended.

2.3 Washers - These shall conform to IS : 2016-1967s.

3. NECESSARY INFORMATION

3.1 For tlcsign and construction of bolt jointed timber units the following information shall be collected:

a) Species and grading of timber,

b) Design data,

c) Moisture content of timber, and

cl) Details of treatment.

4. DESIGN CONSIDERATION

4.1 Loads - The loads shall be calculated as given in IS : 875-196411. The worst corrllJinaLiori ad Iocntion ~JrkJad shall be consitlercd for design. Wind and seismic forces shall not be considered to act sirrlult~~nc~ously.

4.2 Allowable Stresses - The allowable stresses of timber shall be taken as given in IS : 883-19707.

4.3 Dimensions of Members

4.3.1 The minimum thickness of the rnain member in mono chord construction shall be 40 mm.

4.3.2 ‘The minimum thickness of side members shall be 20 mm and shall be half the thickness of main members.

*Specification for strwtural timber in building. +R~:commendations for maximum permissible moisture content of timbrr used for

different purposes ( .wc0wf rmision ). fSpecification for black he,xagon bolts, mlts and lock nuts (diamrter 6 to 39 mm )

and hlxk hexagon screws ( diametcxr 6 to 24 mm ). &7pcrilication for plain washrrs (,/ir2t reoizinn ). /lCodr of practicr, fur structllrnl s:ifl ty of hllilding: I.rrading standards ( rmim? ).

1iCodc ol’ prncticv for d~~~ign of structural timber in building ( t/id r&ion ).

4

IS : 11096 - 1984

4.3.3 The minimum individual thickness of spaced members in split chord construction shall be 20 and 25 mm for web and chord members respectively.

4.4 Bolts

4.4.1 Length of the bolt is the distance from underside of head to the end of threaded portion. The diameter of the bolt in main member should preferably be chosen to give greater length ( t ) to diameter ( d ) ratios. There should be more number of small diameter bolts than small number of large diameter bolts in the joint. A minimum of two bolts for nodal joints and four bolts for lengthening joints shall be provided. Bolts should preferably be arranged in horizontal rows i.e. there should be more: number of rows rather than bolts in a row.

4.4.2 Bolt Bearing Strength of Wood - The allowable load for a bolt in a joint consisting of two members ( single shear ) shall be taken as one half the allowable loads calculated for a three member joint ( double shear ) for the same t/d ratio. The percentage of safe working compressive stress of timber on bolted joints for different t/d ratios shall be as given in Table 1.

4.4.2.1 Where a number ofbolts are used in a joint, the allowable load shall be the sum of the allowable loads for the individual bolts. The factor for different bolts diameter used in calculating safe bearing stress perpendicular to grain in the Joint shall be as given m Table 2. ‘l‘hcse diamctcx fxtors are based OII limited tests only and may therefore be considcrcd as tentative.

4.4.3 Arrangements of Bolts - The end distance, edge distanre and spacing of bolts should lx such as given in 4.4.3.1 to 4.4.3.6 ( see Pig. 1 ).

4.4.3.1 Spacing oJ bnlls iii row

For parallel and perpendicular to grain loading - 4 d,

where d T diameter of bolt.

4.4.3.2 S’acing bctweerl rows of bolls

For pct~mdiculur to grain loading - 2.5 d to 5 d with 2.5 d for t/d ratio of 2 and 5 d ir,r t/d ratio of G or more. For I-ilticls bctwcen 2 to F the spacing shall be obtained by inter-polation.

1;;7r @r&l to grain loadin,g -- At least ( II -4 ) cl with n niiitillIIrrIL of 2.5 d, w&c 71 is total nunrbcr of bolts ~1x1 (I its tii:\rilr\t I’. Also govern4 by net area at critical section Which slroulcl Ix ii0 pc.rccrll of the total :II C’;I ill b,c;trillg IIIIC~C,I. all IJolts.

5

IS : 11096 - 1984

TABLE 1 PERCENTAGE OF SAFE WORKING COMPRESSIVE STRESS OF TIMBER FOR BOLTED JOINTS IN DOUBLE SHEAR

tld RATIO

(1)

1’0

1.5

2’0

2’5

3’0

3’5

4.0

4’5

5.0

5.5

G.0

6.5

7’0

7’5

8’0

8’5

9’0

9’5

10.0

10’5

11’0

11.5

12.0

I_____-._- _--..-.

( Clause 4.4.2 )

STRESS PERCENTAGE ,-~-----~-h___-___--)

Parallel to Grain Perpendicular to ( h ) Grain ( hs )

(2) (3)

100 100

100 96

100 88

100 80

100 72

100 66

96 60

90 56

80 52

72 49

65 46

58 43

52 40

46 39

40 38

36 36

34 34

32 33

30 31

- 31

- 30

_- 30

- 28

--. -- .-.. -. .---..-. -_. .

5

MINIMUM i n-&Id

011 i.5d WHICHEVER

IS GREATER --

lb5d OR HALF THE DISTANCE DETw~EN

ROWS OF BOLfL, WHICHEVER 15, Gkt AT! i?

+ f-nR ’ : 1~ 1 ‘vf ; 1. i r;,. ,a,.:.: $?‘(() i\ ,, L .,

d == cliam~ tvr of thr bolt, II = total numhcr ul’bolts in the joint, and t = thicknpss of main member.

1A SPACING OF BOLTS IN LENGTHENING JOINTS

FIG. 1 TYPICAL SPACING OF BOLTS IN STRUCTURAL JOINTS-Confd 7

i2.5 d FOR t,‘d RATIO-2

5d FOR t/d RATIO-6

,-HEAD HEXAGONAL

d = diametrr of the IwIt, n = total rrurnbc:r of bolts in tllci joint, and

a. ,’ L : I ‘-1, , 1 i

t = thickncw of main member. i 3 i .)rf ! 1~2 I_ .:. I , r,

16 SPACING OF BOLTS AT NODE JOINTS ( JOINTS LOADED PERPENDICULAR TO GRAIN )

FIG. 1 TYPICAL SPAGINCI OF BOLTS IN STRIJOTURAI..JOINW

8

IS :11096 -1984

4.4.3.3 End distance

a) For soft wood in tension

b) For hard wood in tension

C) For all species in compression

4.4.3.4 Edge distance

7d

5d

4d

a) For parallel to grain loading 1.5 d or half the distance between rows of bolts whichever is greater

b) For perpendicular to grain loading ( loaded edge distance )

4d

4.4.3.5 For inclined members, the spacing given above for parallel and perpendicular to grain of wood may be used as a guide and bolts arranged at the joint with respect to loading direction.

4.4.3.6 The bolts shall be arranged in such a manner so as to pass the centre of resistance of bolts through the intersection of the gravity axis of the members. Staggering of bolts shall be avoided as far as possible in case of mrmbcrs Ioadrci paral!ct to grain of wood. For loads acting perpendicular to grain. staggering is preferable to avoid splitting due to weather effects.

TABLE 2 BOLT DIAMETER FACTOR

( Clause 4.4.2.1 )

SL No. DTAMETEIL OB BOLT DIAMETER FACTOR ( df)

(1) (2) (3)

mm i) (i 5’70

iii 10 3’60

11;) 12 3’35

iv1 1G 3’15

v) 20 3’05

vi) 22 3.00

vii) 25 2.90

4 4.4 A typical outline for Appctrdix A.

tlcsign of a bolted joint is given in

IS:11096 - 1984

4.4.4.1 Bolt bearing strength parellel to grain of wood shall in no case be less than that oT lxrpcndicular to grain for use in design calcuIa- tions. If so, lower of the two values may be adopted.

4.4.4.2 Service conditions - Allowable loads calculated apply to bolted joints used under dry service condition as in most covered structures. When a joint is to be used in a location that is continually wet, the allowable load on the bolt may be reduced to one third.

4.4.4.3 Side members - Allowable loads calculated arc side members of WOOLI and which are cxch at lcast one-half the thickness of the main member. If side members are thicker than one-half the thickness of the main member, no increase: is allowed. When wood splice plates are used on both sides of timber which is more than twice the thickness of one splice plate, the allowabie bolt load shall be computed on the basis that the crntrr mernb~ I‘ is ex::ctly t\vicr the thickness of one splice plate, or of the thinnrr splice plate if the splice places are not of equal thickness.

4.4.4.4 SinSqJr nnd multiple shear

Single shear -- ‘I’hc a!lown\)le loads for R bolt in a joint consisting of two mernbcrs otlly ( tingle sl1car ) shall lx OIIF: half the allciwitl~l~: load calclllatrxl liar a 3 rrlc*nd)er joint having n main ln~.~;:i!~cr twice the tliic:i,ness of tllc thinner rricmbcr.

NOTE - Kelz~tiollship between single and multiple shear is thcorctical only.

SPWl 4.4.4.5 A prr-camlxr of not less than

100 shall be provitlc’d at

the ccntrc of the bottom chord UT bolt jointed tirrlber trusses.

5.1 Differellt membc:rs a4 well as splice plate/spacer block sliall IJC first

prepared to the rc+red size and shall IX properly dressed. All the faces of the nrcmbers shall be given at I(.::st one coat of primer in accordance with IS : 23.113 ( Parts 1 a.nd 2 )-1!)67’. Qiantitics of bolts, nuts and washers as rcqlCi_cd shall be procured. Drilling bits of the rc,quircd diamctc rs to carry out the l)rcll(rril~g operation iT necessary shall also bc proc:l1 c,tl.

_~~

10

XS : 111096 - 14f14

5.2 Bolting - The holes in the splice plates sha!! IX r~laccd accurately. The holes in the main members are to be centert C! wit11 tIrc;se to the splice plates. All the holes XC to be bored or drilled prrpc:!diculnr to the silrfarc involved. The bolt holes shall be of such diameter that the bo!ts can be driven easily. Forcible driving should I)e avoided. /2 I,o!t hole: of 1 mm oversize rn;iy bc used as a guide for prcl,oring. 1i’asilcr~s s!rall l,e used between the wood and the bolt head and between the wood and the nut. Washc r’s may not he used if metal splice plates arc used.

5.3 The structural unit after fabrication shall be painted in accordarrce with IS : 2338 ( Parts 1 and 2 )-1967*.

6. MAINTENANCE

6.1 For structures not exposed to weather periodic painting shall be done after every f~vc year interval.

6.2 For cxposcd structures enamel painting shall be done after every two years.

6.3 Bolt shall be tightened after one year of completion of structttrc and subsequently after cvcry two or three years.

CUTLINE FOR DESIGN OF BOLTED JOINT

A-l. Allowable load on OIIC bolt ( unit bearing stress ) in 2. .joirlt wit\1

wooden splice plntcs shall not be greater than the values off’, Q or .N as determined by one of the following equations :

a) For loads parallel to grain

p ==fCll R Xl,

b) For loads perpendicular ( normal ) to grain

Q = SOI a AZ, df and

c) For loads at an angle to grain

11

I§ : 11096 - 1984

where

P is load on bolt parallel to grain, in N;

Qis load on a bolt perpendicular ( normal ) to grain, in N;

F is load acting on a bolt at an angle to grain, in N;

f cl1 is permissible unit stress in compression parallel to grain in

N/ mm2;

.for is permissible unit stress in compression perpendicular to grain in N/mms;

a is projected area of bolt in main member ( mm2 ) = ( t x d );

X1 is percentage factor for t/d ratio, parallel grain;

As is percentage factor for t/d ratio, perpendicular to grain;

df is bolt diameter factor for perpendicular to grain;

6 is the angle of load to grain direction;

d is diameter of the bolt;

n is total number or bolts in the joint; md

t is thickness of main member.

12

IS: 11096 - 1984

( Continaedfiorn pags 2 )

Me?llOers Representing

SIII~I V. N. DESHPANDE Engineer-in-Chief’s Branch, Army Headquarters, Nrw Delhi

SHRI S. K. GUPTA ( Alternate ) DIRECTOI~ Indian Plywood Industries Research Institute,

Bangalore Dn H. N. JAOADEESH ( Alternate )

DR. C. D. Dwrvsrn Ministry of Defence ( R & D ) SHIU R. A. Pnas~ ( Alternate)

SJIRI P. N. GAIX Institution of Surveyors, New Delhi SIIILI M. S. KOPPIKAR Pest Control ( India) Pvt Ltd, Bombay

SHI~I T. R. R AO ( Alternate ) SHRI G. K. MA.JUMDAH Hindustan Prefab Ltd, New Drlhi

SHEI H. S. PASIUCHA ( Alternate ) SHRI J. SlCNDDPTA National Buildings Organization, New Delhi

Srra~ A. K. LAL ( Alternate ) SUPERINTENUINO SUILVEYOI~ OF Central Public Works Drpartmcnt ( Architectural

WOI<KCi Ngw D~,,ir ( CZ ), CPWD, Wing ), New Delhi

SUI~VEYOI~ OF WOILI~S ( CZ ) ( Alternate ) S u P B n I N T E N n I N o ENGINEER Public Works Drpartmcnt, Govrrnmcnt of

( PLANNINa) PWD ( B & Ii ), Madhya Pradc&, l3holz1l Ul!OPAL

13

INTERNATIONAL SYSTEM OF UNITS ( SI UNITS)

Baes Units

Quaotity

Length Mass

Time Electric current

Thermodynamic temperature

Luminous intensity

Amount of substance

Supplementary Units

Quantity

Plane angle

Solid angle

Derived Units

Quantity

Force

Energy

Power Flux

Flux density

Frequency Electric conductance

Electromotive force

pregsure, stress

Unit

metre kilogram

second ampere

kelvin

candela

mole

Unit

radian

steradian

Unit

newton

joule

watt weber tesla

hertz

siemens

volt

Pascal

Symbol

m

kg

:

K

cd fllOl

Symbol

rad

sr

Symbol

N

J

W

Wb T

HZ

S V

P8

Oeflnition

1 N = 1 kg.m/sa

1 J = 1 N.m

1 W = 1 J/s

1 Wb = 1 v.s 1 T = 1 Wb/ma 1 Hz = 1 c/s (s-1)

1 S = 1 A/V 1 V = 1 W/A

1 Pa = 1 N/m’