875 5 IS CODE FOR WIND LOADS

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875 2IS CODE FOR WIND LOADS

Text of 875 5 IS CODE FOR WIND LOADS

  • 1. IS : 875( Part 5 ) - 1997 ( Reeed1997 ) Indian StandardCODE OF PRACTICE FORDESIGN LOADS (OTHER THAN EARTHQUAKE)FOR BUILDINGS AND STRUCTURES PART 5 SPECIAL LOADS AND COMBINATIONS ( Second Revision )Fourth Reprint NOVEMBER 1997UDC 624042:00676 BURRAU MANAK

2. IS : 875 ( Part 5 ) - 1987Igdian StandardCODE OF PRACTICE F6RDESIGN LOADS (OTHER THAN EARTHQUAKE) FOR BUILDINGS AND STRUCTURESPART 5 SPECIAL LOADS AND LOAD COMBINATIONS( Second Revision ) Structural Safety Sectional Committee, BDC 37 Chqirman R~prcssntingBBIQ DE L. V. RAYAKRI~~NAEngineer-in-ChiefsBranch, Army Headquarters, New Delhi MNl?lbrrtDR K. G. BHATIA Bharat Heavy ElectricalsLimited,Corporate Research & Development Division, HyderabadSHBI M. S. BHATIAIn perronal capacity ( A-2136, Safdarjang Enclave, New Delhi )SHEI N. K. BEATTACEABYA Engineer-in-Chiefs Branch, Army Headquarters, New DelhiSHBI S. K. MALHOTI~A [ Allsraals 1DE S. C. CHAKRABARTIden;tr~rk~t$ldingResearch Institute( CSIR ),SHBI A. DAT~A ( Alfernate )CHIEF ENQINEEB ( ND2 ) II Central Public Works Department, New DelhiSTJPERINTBNDINQSURVEYOR OFWOBKE ( NDZ ) II ( Altsrnats 1DE P. DAYABATNAMIndian Institute of Technology, KanpurDB A. S. R. SAI ( Altarnats )D~UTY MUNICIPAL COYMISSI- Municipal Corporation of GreaterBombay,ONpa ( ENQo )BombayCITY ENQINEI~R ( Altern& )DIBEOTOR ( CMDD-I ) Central Water Commission, New DelhiDEPUTY DIBEC~O~ ( CMDD-I ) ( Altcmats )MAJ-GmA. M. GOQLEKABInstitution of Engineers ( India ), CalcuttaPBO~ D. N. TBIKHA ( Altmnatr j( Continurd on page 2 ) 0 coplright 1988BUREAU OF INDIANSTANDARDS This publication is protected under the Zndian Copyright Act ( XIV of 1957 ) and reproduction in whole or in part by any means except with written permission of the publisher shall be deemed to be an infringement of copyright under the said Act. 3. IS : 875 ( Part 5 ) - 1987( Continasdfrom @gc 1 )Members Rep.wntingS~nr A. C. GWPTA Nati;: DzIymal Power CorporationLtd,Snap P. SEN GUPTAStewaFts and Lloydaof India Ltd, CalcuttaSoar M. M. Grtosn ( Aft~r~k)SHBI G. B. JAHAQIRDARNational IndustrialDevelopmentCorporationLtd, New DelhiJ o I N T DIRECTOR STANDARDS Ministry of Railways (B&S ), CBSxsr S. P. JO~HI Tata ConsultingEngineers,New Delhi SHRI A. P. MULL ( Alternate )SHBI S. R. KTJLKARNI M. N. Dastur& Co, Calcutta Saal S. N. PAL ( Alternate )SEW H. N. MISHBA Forest Research Instituteand Colleges, DebraDunSHBI R. K. PUNEANI ( Alternate )SHRI T. K. D. MUNSHIEngineers India Ltd, New DelhiDR C. RAJKU~A~National Council for Cement & BuildingMaterials, New DelhiDa M. N. KESHWA RAOStruc;;;iaxrgineeringResearch Centre ( CSIR 1. SHBI M. V. DHABAIVEEPATEY ( Altcrnafu )SHRI T. N. SUBBA RAOGammonIndia Ltd, Bombay DR S. V. LONEAR ( Alkrnafr )SBEI P. K. RAYIndian EngineeringAssociation, Calcutta SHRI P. K. MUKHERJEE ( Altcrnofe )SHRI S. SEETEAR~MAN Ministryof SurfaceTransport( Roads Wing ), New Delhi SHRI S. P. CEAKRABORTYAlternate )Srrnr M. C. SHARMAIndian MeteorologicalDepartment,New DelhiSHRI K. S. SRINIVAYAN National Buildings Organization, New Delhi SHLU A. K. LAL ( Altcrnafc)SHRI SUSHIL Knri~ National Building Construction CorporationLtd, New DelhiSnnr G. RAMAN.Director General, BIS ( Ex-o&io Mmbcr )Director ( CivEngg )SHRI B. R. NARAYANAPPA Deputy Director ( Civ Engg ), BIS ( Conlinud on page 18 )2 4. IS t 875( Part 5 ) - 1987 Indian StandardCODE OF PRACTICE FOR DESIGN LOADS (OTHER THAN EARTHQUAKE) FOR BUILDINGS AND STRUCTURES PART 5 SPECIAL LOADS AND LOAD COMBINATIONS( Second Revision )0. FOREWORD 0.1 This Indian Standard ( Part 5 ) ( Second Revision ) was adopted by the Bureau of Indian Standards on 3 1 August 1987, after the draft finaliz- ed by the StructuralSafety SectionalCommittee had been approved by the Civil EngineeringDivision Council.0.2 A buildinghas to perform many functionssatisfac orily. Amongst these functions are the utility of the building for the intendeduse and occupancy,structural safety, fire safety; and compliancewith hygienic,ganitation, ventilation and day light standards.The design of the buildingis dependent upon the minimum requirementsprescribedfor each of theabove functions. The minimum requirementspertainingto the structural safety of buildings are being covered in this code by way of laying downminimum design loads which have to be assumed for dead loads, imposedloads, snow loads and other external loads, the structure would be requir-ed to bear. Strict conformity to loading standards recommendedin thiscode, It is hoped,will not only ensure the structural safety of the buildingswhich are being designed and constructedin the country and therebyreduce the hazards to life and property caused by unsafe structures, butalso eliminate the wastage caused by assuming unnecessarilyheavy load-ings. Notwithstandingwhat is stated regarding the structuralsafety ofbuildings,the applicationof the provisions should be carried out by com-petent and responsible structural designer who would satisfy himself thatthe structure designed in accordancewith this code meets the desiredperformance requirementswhen the same is carried out according tospecifications.0.3 This standard code of practice was first published in 1957 for theguidance of civil engineers, designers and architects associated with plann-ing and design of buildings.It included the provisions for basic design 3 5. IS t 875 ( Part 5 ) - 1987loads ( dead loads, live loads, wind loads and seismicloads ) to be assumedin the design of buildings. In its first revision in 1964, the wind pressureprovisions were modified on the basis of studies of wind phenomenon andits effects on structures, undertaken by the special committee in consultationwith the Indian Meteorological Department. In addition to this, newclauses on wind loads for butterfly type structures were included; windpressure coefficients for sheeted roofs both curved and sloping were modi-fied; seismic load provisions were deleted ( separate code having beenprepared ) and metric system of weights and measurements was adopted. 0.3.1 With the increased adoption of the code, a number of commentswere received on the provisions on live load values adopted for differentoccupancies. Simultaneously live load surveys have been carried out inAmerica, Canada and other countries to arrive at realistic live loads basedon actual determinationof loading ( movable and immovable ) indifferent occupancies. Keeping this in view and other developments in thefield of wind engineering, the committee responsible for the preparation ofthe standard decided to prepare second revision in the following five parts: Part 1 Dead loads Part 2 Imposed loads Part 3 Wind loads Part 4 Snow loads Part 5 Special loads and load combinations. Earthquake load is covered in a separate standard, namely IS : 18931984* which should be considered along with the above loads. 0.3.2 This code ( Part 5 ) deals with loads and load effects ( other thanthose covered in Parts 1 to 4, and seismic loads ) due to temper-ature changes, internally generating stresses ( due to creep, shrinkage,differential settlement, etc ) in the building and its components, soil andhydrostatic pressure, accidental loads, etc. This part also includes guid-ance on load combinations.0.4 The code has taken into account the prevailing practices in regard toloading standards followed in this country by the various municipal autho-rities and has also taken note of the developments in a number of countriesabroad. In the preparation of this code, the following national standardshave been examined:a) National Building Code of Canada ( 1977 ) SupplementNo. 4. Canadian Structural Design Manual.*Criteria for earthquakeresistantdesignof structures( thirdrenision ).4 6. I& : 835 ( Part 5 ) - 1987 b) DS 410-1983 Code of practice for loads for the design of struct-ures. Danish Standards Institution.4 NZS 4203-1976 New Zealand Standard General structural designand design loading for building. Standards Association of NewZealand. 4ANSI A 58.1-1982 American Standard Building code require-ments for minimum design loads in buildings and other structures.i. SCOPE1.1 This code ( Part 5 ) deals with loads and load effects due to temper-ature changes, soil and hydrostatic pressures, internally generating stresses ( due to creep, shrinkage, differential settlement, etc ), accidental loadsetc, to be considered in the design of buildings as appropriate.This partalso includes guidance on load combinations. The nature of loads to beconsidered for a particular situation is to be based on engineeringjudgement.2. TEMPERATUREEFFECTS2.1 Expansion and contraction due to changes in temperature of thematerials of a structure shall be considered in design. Provision shall bemade either to relieve the stress by provision of expansion/contractionjoints in accordance with IS : 3414-1968* or design the structure to carry additional stresses due to temperature effects as appropriate to theproblem. 2.1.1 The temperature range varies for different regions and underdifferent diurnal and seasonal conditions. The absolute maximum andminimum temperature which may be expected in different localities inthe country are indicated in Fig. 1 and 2 respectively. These figures maybe used for guidance in assessing the maximum variations of temperature. 2.1.2 The temperatures indicated in Fig. 1 and 2 are the air tempera-tures in the shade. The range of variation in temperature of the buildingmaterials may be appreciably greater or less than the variation of airtemperature and is influenced by the condition of exposure and the rate atwhich the materials composing the structure absorb or radiate heat. Thisdifference in temperature variations of the material and air should be givendue consideration. 2.1.3 The structural analysis must take into account: (a) changes of themean ( through the section ) temperature in relation to the initial temper-ature ( st ), and (b) the temperature gradient through the section, *Code of practice for des