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Indian StandardGENERAL CONSTRUCTION INSTEEL CODE OF PRACTICE

( Third Revision)

ICS 77.140.01

Q BIS 2007BUREAU OF INDIAN STANDARDSMA.NAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

December 2007 Price Rs. 1130.!?!?

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Structural Engineering and Structural Sections Sectional Committee, CED 7

FOREWORDThis Indian Standard (Third Revision) was adopted by the Bureau of Indian Standards, after the draft finalizedby the Structural Engineering and Structural Sections Sectional Committee had been approved by the CivilEngineering Division Council.The steel economy programme was initiated by erstwhile Indian Standards Institution in the year 1950 with theobjective of achieving economy in the use of structural steel by establishing rational, efficient and optimumstandards for structural steel products and their use. IS 800: 1956 was the first in the series of Indian Standardsbrought out under this programme. The standard was revised in 1962 and subsequently in 1984, incorporatingcertain very importmt changes.IS 800 is the basic Code for general construction in steel structures and is the prime document for any structuraldesign and has influence on many other codes governing the design of other special steel structures, such astowers, bridges, silos, chimneys, etc. Realising the necessity to update the standard to the state of the art of thesteel construction technology and economy, the current revision of the standard was undertaken. Considerationhas been given tO the de~elopments taking place in the country and abroad, and necessary modifications andadditions have been incorporated to make the standard more useful.The revised standard will enhance the confidence of designers, engineers, contractors, technical institutions,professional bodies and the industry and will open a new era in safe and economic construction in steel.In this revision the following major modifications have been effected:

a) In view ofthe development and production of new varieties of medium and high tensile structural steelsin the country, the scope of the standard has been modified permitting the use of any variety of structuralsteel provided the relevant provisions of the standard are satisfied.b) The standard has made reference to the Indian Standards now available for rivets; bolts and other fasteners.

c) The standard is based on limit state method, reflecting the latest developments and the state of the art.The revision of the standard was based on a review carried out and the proposals framed by Indian Institute ofTechnology Madras (IIT Madras). The project was supported by Institute of Steel Development and Growth(INSDAG) Kolkata. There has been considerable contribution from INSDAG and IIT Madras, with assistancefrom a number of academic, research, design and contracting institutes/organizations, in the preparation of therevised standard.In the formulation of this standard the following publications have also been considered:AS-4 100-1998 Steel structures (second edition), Standards Australia (Standards Association of Australia),Homebush, NSW 2140,BS-5950-2000 Structural use of steelwork in buildings:Part 1 Code of practice for design in simple and continuous construction: Hot rolled sections, British

Standards Institution, London.CAN/CSA- Limit states design of steel structures, Canadian Standards Association, Rexdale (Toronto),S16.1-94 Ontario, Canada M9W 1R3.ENV [993-1-1: Eurocode 3: Design of steel structures:1992 Part 1-1 General rules and rules for buildingsThe composition of the Committee responsible for the formulation of this standard is given in Annex J.For the purpose of deciding whether a particular requirement of this standard, is complied with, the final value,observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance withIS 2:1960 Rules for rounding off numerical values (revised). The number of significant places retained in therounded off value should be the same as that of the specified value in this standard.

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1S 800:2007

Contents

SECTION 1 GENERAL1.1 scope1.2 References1.3 Terminology1,4 Symbols1.5 Units1.6 Standard Dimensions, Form and Weight1.7 Plans and Drawings1.8 Convention for Member Axes

SECTION 2 MATERIALS2.1 General2.2 Structural Steel2.3 Rivets2,4 Bolts, Nuts and Washers2.5 SteeI Casting2.6 Welding Consumable2.7 Other Materials

SECTION 3 GENERAL DESIGN REQUIREMENTS3.1 Basis for Design3.2 Loads and Forces3.3 Erection Loads3.4 Temperature Effects3.5 Load Combinations3.6 Geometrical Properties3.7 Classification of Cross-Sections3.8 Maximum Effective Slenderness Ratio3.9 Resistance to Horizontal Forces3.10 Expansion Joints

SECTION 4 METHODS OF STRUCTURAL ANALYSIS4.1 Methods of Determining Action Effects4.2 Forms of Construction Assumed for Structural Analysis4,3 Assumptions in Analysis4.4 Elastic Analysis4.5 Plastic Analysis4.6 Frame Buckling Analysis

SECTION 5 LIMIT STATE DESIGN5.1 Basis for Design5.2 Limit State Design5.3 Actions5.4 Strength5,5 Factors Governing the Ultimate Strength5.6 Limit State of Serviceability

SECTION 6 DESIGN OF TENSION MEMBERS6.1 Tension Members6.2 Design Strength Due to Yielding of Gross Section6.3 Design Strength Due to Rupture of Critical Section6.4 Design Strength Due to Block Shear

111151111111212121212151515151515151616161717202021222222232425262727282829303032.,32323233

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IS 800:2007SECTION 7 DESIGN OF COMPRESS1ON MEMBERS

7.1 Design Strength7.2 Effective Length of Compression Members7.3 Design Details7.4 Column Bases7.5 Angle Struts7.6 Laced Columns7.7 Battened Columns7.8 Compression Members Composed of Two Components Back-to-Back

SECTION 8 DESIGN OF MEMBERS SUBJECTED TO BENDING8.1 General8.2 Design Strength in Bending (Flexure)8.3 Effective Length for Lateral Torsional Buckling8.4 Shear8.5 Stiffened Web Panels8.6 Design of Beams and Plate Girders with Solid Webs8.7 Stiffener Design8.8 Box Girders8.9 Purlins and Sheeting Rails (Girts)8.10 Bending in a Non-Principal Plane

SECTION 9 MEMBER SUBJECTED TO COMBINED FORCES9.1 General9.2 Combined Shear and Bending9.3 Combined Axial Force and Bending Moment

SECTION 10 CONNECTIONS10.1 General10.2 Location Details of Fasteners10.3 Bearing Type Bolts10.4 Friction Grip Type Bolting10.5 Welds and Welding10.6 Design of Connections10.7 Minimum Design Action on Connection10.8 Intersections10.9 Choice of Fasteners10.10 Connection Components10.11 Analysis of a Bolt/Weld Group10.12 Lug Angles

SECTION 11 WORKING STRESS DESIGN11.1 General11.2 Tension Members11.3 Compression Members11.4 Members Subjected to Bending11.5 Combined Stresses11.6 Connections

SECTION 12 DESIGN AND DETAILING FOR EARTHQUAKE LOADS12.1 General12.2 Load and Load Combinations12.3 Response Reduction Factor12.4 Connections, Joints and Fasteners12.5 Columns12.6 Storey Drift12.7 Ordinary Concentrically Braced Frames (OCBF)

34343546464748505252525254596063656969696969697073737374767881828282828383848484848585868787878787878888

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12.8 Special Concentrically Braced Frames (SCBF)12.9 Eccentrically Braced Frames (EBF)1~.10 Ordinav Moment Frames (OMF)12.11 Special Moment Frames (SMF)12.12 Column Bases

SECTION 13 FATIGUE13.1 General13.2 Design13.3 Detail Category13.4 Fatigue Strength13.5 Fatigue Assessment13.6 Necessity for Fatigue Assessment

SECTION 14 DESIGN ASSISTED BY TESTING14.1 Need for Testing14.2 Types of Test14.3 Test Conditions14.4 Test Loading14.5 Criteria for Acceptance

SECTION 15 DURABILITY15.1 General15.2 Requirements for Durability

SECTION 16 FIRE RESISTANCE16.1 Requirements16.2 Fire Resistance Level16.3 Period of Structural Adequacy (PSA)16.4 Variation of Mechanical Properties of Steel with Temperature16.5 Limiting Steel Temperature16.6 Temperature Increase with Time in Protected Members16.7 Temperature Increase with Time in Unprotected Members16.8 Determination of PSA from a Single Test16.9 Three-Sided Fire Exposure Condition16.10 Special Considerations16.11 Fire Resistance Rating

SECTION 17 FABRICATION AND ERECTION17.1 General17.2 Fabrication Procedures17.3 Assembly17.4 Riveting17.5 Bolting17.6 Welding17.7 Machining of Butts, Caps and Bases17.8 Painting17.9 Marking17.10 Shop Erection17.11 Packing17.12 Inspection and Testing17.13 Site Erection17.14 Painting After Erection17.16 Steelwork Tenders and Contracts

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IS 8~0 :20078889899090919191929399100100100101102102103103103103105105105106106106107108108108108109110110110112113113113113113114114114114114116116

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IS 800:2007ANNEX A LIST OF REFERRED INDIAN STANDARDS 117ANNEX B ANALYSIS AND DESIGN METHODS

B-1 Advanced Structural Analysis and DesignB-2 Second Order Elastic Analysis and DesignB-3 Frame Instability Analysis

ANNEX C DESIGN AGAINST FLOOR VIBRATIONC-1 GeneralC-2 Annoyance CriteriaC-3 Floor FrequencyC-4 DampingC-5 Acceleration

ANNEX D DETERMINATION OF EFFECTIVE LENGTH OF COLUMNSD-1 Method for Determining Effective Length of Columns in FramesD-2 Method for Determining Effective Length for Stepped Columns (see 7.2.2)D-3 Effective Length for Double Stepped Columns

ANNEX E ELASTIC LATERAL TORSIONAL BUCKLINGE-1 Elastic Critical Moment

ANNEX F CONNECTIONSF-1 GeneralF-2 Beam SplicesF-3 Column SpliceF-4 Beam-to-Column ConnectionsF-5 Column Bases

ANNEX G GENERAL RECOMMENDATIONS FOR STEELWORK TENDERSAND CONTRACTSG-1 GeneralG-2 Exchange of InformationG-3 Information Required by the Steelwork DesignerG+4 Information Required by Tenderer (If Not Also Designer)G-5 DetailingG-6 Time ScheduleG-7 Procedure on SiteG-8 InspectionG-9 Maintenance

ANNEX H PLASTIC PROPERTIES OF BEAMS

120120120120121121121121122122122122124124128128130130130130131134135

135135135136137137137137137138

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IS 800:2007

Indian StandardGENERAL CONSTRUCTION INSTEEL CODE OF PRACTICE

( Third Revision)SECTION 1GENERAL

1.1 Scope1.1.1 This standard applies to general constructionusing hot rolled steel sections joined using riveting,bolting and welding. Specific provisions for bridges,chimneys, cranes, tanks, transmission line towers, bulkstorage structures, tubular structures, cold formed lightgauge steel sections, etc, are covered in separatestandards.1.1.2 This standard gives only general guidance as regardsthe various loads to be considered in design. For the actualloads and load combinations to be used, reference maybe made to IS 875 for dead, live, snow and wind loadsand to IS 1893 (Part 1) for earthquake loads.1.1.3 Fabrication and erection requirements coveredin this standard are general and the minimum necessaryquality of material and workmanship consistent withassumptions in the design rules. The actualrequirements may be further developed as per otherstandards or the project specification, the type ofstructure and the method of construction.1.1.4 For seismic design, recommendations pertainingto steel frames only are covered in this standard. Formore detailed information on seismic design of otherstructural and non-structural components, refrenceshould be made to IS 1893 (Part 1) and other specialpublications on the subject.1.2 ReferencesThe standards listed in Annex A contain provisionswhich through reference in this text, constituteprovisions of this standard. At the time of publication,the editions indicated were valid. All standards aresubject to revision and parties to agreements based onthis standard are encouraged to investigate thepossibility of applying the most recent editions of thestandards indicated in Annex A.1.3 TerminologyFor the purpose of this standard, the followingdefinitions shall apply.

1.3.1 Accidental Loads Loads due to explosion,impact of vehicles, or other rare loads for which thestructure is considered to be vulnerable as per the user.1.3.2 Accompanying Load Live (imposed) loadacting along with leading imposed load but causinglower actions and/or deflections.1.3.3 Action Effect or Load Effect The internal force,axial, shear, bending or twisting moment, due toexternal actions and temperature loads,1.3.4 Action The primary cause for stress ordeformations in a structure such as dead, live, wind,seismic or temperature loads.1.3.5 Actual Length The length between centre-to-centre of intersection points, with supporting membersor the cantilever length in the case of a free standingmember.1.3.6 Beam A member subjected predominantly tobending.1.3.7 Bearing Type Connection A connection madeusing bolts in snug-tight condition, or rivets wherethe load is transferred by bearing of bolts or rivetsagainst plate inside the bolt hole.1.3.8 Braced Member A member in which therelative transverse displacement is effectively preventedby bracing.1.3.9 Brittle Cladding Claddings, such as asbestoscement sheets which get damaged before undergoingconsiderable deformation.1.3.10 Buckling Load The load at which an element,a member or a structure as a whole, either collapses inservice or buckles in a load test and develops excessivelateral (out of plane) deformation or instability.1.3.11 Buckling Strength or Resistance Force ormoment, which a member can withstand withoutbuckling.1.3.12 Bui/t-ap Section A member fabricated byinterconnecting more than one element to form acompound section acting as a single member.1.3.13 Camber- Intentionally introduced pre-curving(usually upwards) in a system, member or any portion

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IS 800:2007of a member with respect to its chord. Frequently,camber is introduced to compensate for deflections ata specific level of loads.1.3.14 Characteristic Load (Action) The value ofspecified load (action), above which not more than aspecified percentage (usually 5 percent) of samples ofcorresponding load are expected to be encountered.1.3.15 Characteristic Yield/Ultimate Stress Theminimum value of stress, below which not more thana specified percentage (usually 5 percent) ofcorresponding stresses of samples tested are expectedto occur.1.3.16 Column A member in upright (vertical)position which supports a roof or floor system andpredominantly subjected to compression.1.3.17 Compact Section A cross-section, which candevelop plastic moment, but has inadequate plasticrotation capacity needed for formation of a plasticcollapse mechanism of the member or structure.1.3.18 Constant Stress Range The amplitudebetween which the stress ranges under cyclic loadingis constant during the life of the structure or a structuralelement.1.3.19 Corrosion An electrochemical process overthe surface of steel, leading to oxidation of the metal.1.3.20 Crane Load Horizontal and vertical loadsfrom cranes.1.3.21 Cumulative Fatigue Total damage due tofatigue loading of varying stress ranges.1.3.22 Cut-o~Limit The stress range, correspondingto the particular detail, below which cyclic loading neednot be considered in cumulative fatigue damageevaluation (corresponds to 108 numbers of cycles inmost cases).1.3.23 Dead Loads The self-weights of allpermanent constructions and installations including theself-weight of all walls, partitions, floors, roofs, andother permanent fixtures acting on a member.1.3.24 Dejection It is the deviation from thestandard position of a member or structure.1.3.25 Design Life Time period for which a structureor a structural element is required to perform itsfunction without damage.1.3.26 Design Load/Factored Load A load valueob~~ined by multiplying the characteristic load with aload factor.1.3.27 Design Spectrum Frequency distribution ofthe stress ranges from all the nominal loading eventsduring the design life (stress spectrum).

1.3.28 Detail Category Designation given to aparticular detail to indicate the S-N curve to be used infatigue assessment.1.3.29 Discontinuity A sudden change in cross-section of a loaded member, causing a stressconcentration at the location.1.3.30 Ductility It is the property of the material ora structure indicating the extent to which it can deformbeyond the limit of yield deformation before failure orfracture. The ratio of ultimate to yield deformation isusually termed as ductility.1.3.31 Durability It is the ability of a material toresist deterioration over long periods of time.1.3.32 Earthquake Loads The inertia forcesproduced in a structure due to the ground movementduring an earthquake.1.3.33 Edge Distance Distance from the centre of afastener hole to the nearest edge of an elementmeasured perpendicular to the direction of loadtransfer.1.3.34 Eflective Lateral Restraint Restraint, thatproduces sufficient resistance to prevent deformationin the lateral direction.1.3.35 Effective Length Actual length of a memberbetween points of effective restraint or effectiverestraint and free end, multiplied by a factor to takeaccount of the end conditions in buckling strengthcalculations.1.3.36 Elastic Cladding Claddings, such as metalsheets, that can undergo considerable deformationwithout damage.1.3.37 Elastic CriticalMoment The elastic moment,which initiates lateral-torsional buckling of a laterallyunsupported beam.1.3.38 Elastic Design Design, which assumes elasticbehaviour of materials throughout the service loadrange.1.3.39 Elastic Limit It is the stress below which thematerial regains its original size and shape when theload is removed. In steel design, it is taken as the yieldstress.1.3.40 End Distance Distance from the centre of afastener hole to the edge of an element measuredparallel to the direction of load transfer.1.3.41 Erection Loads The actions (loads anddeformations) experienced by the structure exclusivelyduring erection.1.3.42 Erection Tolerance Amount of deviationrelated to the plumbness, alignment, and level of the

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element as a whole in the erected position. Thedeviations are determined by considering the locationsof the ends of the element.1.3.43 Exposed Surface Area to Mass Ratio Theratio of the surface area exposed to the fire (in mm2) tothe mass of steel (in kg).

NOTE In the case of members with tire protection materialapplied, the exposed surface area is to be taken as the internalsur~acearea of the fire protection material.1.3.44 Fabrication Tolerance Amount of deviationallowed in the nominal dimensions and geometry infabrication activities, such as cutting to length, finishingof ends, cutting of bevel angles, etc.1.3.45 Factorof Safety The factor by which the yieldstress of the material of a member is divided to arriveat the permissible stress in the material.1.3.46 Fatigue Damage caused by repeatedfluctuations of stress, leading to progressive cmckingof a structural element.1.3.47 Fatigue Loading Set of nominal loadingevents, cyclic in nature, described by the distributionof the loads, their magnitudes and the number ofapplications in each nominal loading event.1.3.48 Fatigue Strength The stress range for acategory of detail, depending upon the number ofcycles it is required to withstand during design life.1.3.49 Fire Exposure Condition

a) Three-sidedfire exposure condition Steelmember incorporated in or in contact with aconcrete or masonry floor or wall (at leastagainst one surface).NOTES1Three-sided fire exposure condition is to be consideredseparately unless otherwise specified (see 16.10).2 Members with more than one face in contact with aconcrete or masonry floor or wall may be treated asthree-sided tire exposure.

b) Four-sided jire exposure condition Steelmember, which may be exposed to fire on allsides.

1.3.50 Fire Protection System The fire protectionmaterial and its method of attachment to the steelmember.1.3.51 Fire Resistance The ability of an element,component or structure, to fulfil for a stated period oftime, the required stability, integrity, thermal insulationand/or other expected performance specified in astandard fire test.1.3.52 FireResistanceLevelThe fwe resistance gradingperiod for a structural element or system, in minutes,which is required to be attained in the standard fire test.

IS 800:20071.3.53 Flexural Stiffness Stiffness of a memberagainst rotation as evaluated by the value of bendingdeformation moment required to cause a unit rotationwhile all other degrees of freedom of the joints of themember except the rotated one are assumed to berestrained.1.3.54 Friction Type Connection Connectioneffected by using pre-tensioned high strength boltswhere shear force transfer is due to mobilisation offriction between the connected plates due to clampingforce developed at the interface of connected platesby the bolt pre-tension.1.3.55 Gauge The spacing between adjacent parallellines of fasteners, transverse to the direction of load/stress.1.3.56 Gravity Load Loads arising due togravitational effects.1,3.57 GwssetPlate The plate to which the membersintersecting at a joint are connected.1.3.58 High Shear High shear condition is causedwhen the actual shear due to factored load is greaterthan a certain fraction of design shear resistance(see 9.2.2).1.3.59 Imposed (Live) Load The load assumed tobe produced by the intended use or occupancyincluding distributed, concentrated, impact, vibrationand snow loads but excluding, wind, earthquake andtemperature loads.1.3.60 Instability The phenomenon which disablesan element, member or a structure to carry further loaddue to excessive deflection lateral to the direction ofloading and vanishing stiffness.1.3.61 Lateral Restraint for a Beam (see 1.3.34)1.3.62Leading Imposed Load Imposed load causinghigher action and/or deflection.1.3.63 Limit State Any limiting condition beyondwhich the structure ceases to fulfil its intended function(see also 1.3.86).1.3.64 Live Load (see 1.3.59)1.3.65 Load An externally applied force or action(see also 1.3.4).1.3.66 Main Member A structural member, whichis primarily responsible for carrying and distributingthe applied load or action.1.3,67 Mill Tolerance Amount of variation allowedfrom the nominal dimensions and geometry, withrespect to cross-sectional area, non-parallelism of

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IS 800:2007flanges, and out of straightness such as sweep orcamber, in a product, as manufactured in a steel mill.1.3.68 Normal Stress Stress component actingnormal to the face, plane or section.1.3,69 Partial Safety Factor The factor normallygreater than unity by which either the loads (actions)are multiplied or the resistances are divided to obtainthe design values.1.3.70 Period of Structural Adequacy under Fire The time (t), in minutes, for the member to reach thelimit state of structural inadequacy in a standard firetest.1.3.71 Permissible S~rcss When a structure is beingdesigned by the working stress method, the maximumstress that is permitted to be experienced in elements,members or structures under the nominal/service load(action).1.3.72 Pitch The centre-to-centre distance betweenindividual fasteners in a line, in the direction of load/stress.1.3.73 Plastic Collapse The failure stage at whichsufficient number of plastic hinges have formed dueto the loads (actions) in a structure leading to a failuremechanism.1.3.74 Plastic IMsi,gn Design against the limit stateof plastic collapse.1.3.75 Plastic Hinge A yielding zone withsignificant inelastic rotation, which forms in a member,when the plastic moment is reached at a section.1.3.76 Plastic Mo~nent Moment capacity of a cross-section when the entire cross-section has yielded dueto bending moment.1.3.77 Plastic Section Cross-section, which candevelop a plastic hinge and sustain piastic moment oversufficient plastic rotation required for formation ofplastic failure mechanism of the member or structure.1,3.78 Poissons Ratio It is the absolute value ofthe ratio of lateral strain to longitudinal strain underuni-axial Ioading.1.3.79 Proof Stress The stress to which high strengthfriction grip (HSFG) bolts are pre-tensioned.1.3,80 Proof Testing The application of test loadsto a structure, sub-structure, member or connection toascertain the structural characteristics of only thatspecific unit.1.3.81 Prototype Testing Testing of structure, sub-structure, members or connections to ascertain thestructural characteristics of that class of structures, sub-

structures, members or connections that are nominallyidentical (full scale) to the units tested.1.3.82 Prying Force Additional tensile forcedeveloped in a bolt as a result of the flexing of aconnection component such as a beam end plate or legof an angle.1.3.83 Rotatiort The change in angle at a jointbetween the original orientation of two linear memberand their final position under Ioadlng.1.3.84 Secondary Member Member which isprovided for overall stability and or for restraining themain members from buckling or similar modes offailure.1.3.85 Semi-compact Section Cross-section, whichcan attain the yield moment, but not the plastic momentbefore failure by plate buckling.1.3.86 Serviceability .LirnitState A limit state ofacceptable service condition exceedence of whichcauses serviceability failure.1.3.87 Shear Force The inplane force at anytransverse cross-section of a straight member of acolumn or beam.1.3.88 Shear Lag The in plane shear deformationeffect by which concentrated forces tangential to thesurface of a plate gets distributed over the entire sectionperpendicular to the load over a finite length of theplate along the direction of the load.1.3.89 Shear Stress The stress component actingparallel to a face, plane or cross-section.1.3.90 Slender Section Cross-section in which theelements buckle locally before reaching yield moment.1.3.91 Slenderness Ratio The ratio of the effectivelength of a member to the radius of gyration of thecross-section about the axis under consideration.1.3.92 Slip Resistance Limit shear that can beapplied in a friction grip connection before slip occurs.1.3.93 S-N Curve The curve defining the relationshipbetween the number of stress cycles to failure (N,c) ata constant stress range (SC),during fatigue loading ofa structure.1.3.94 Snow Load Load on a structure due to theaccumulation of snow and ice on surfaces such as roof.1.3.95 Snug iightThe tightness of a bolt achievedby a few impacts of an impact wrench or by the fulleffort of a person using a standard spanner.1.3.96 Stability Limit State A limit statecorresponding to the loss of static equilibrium of astructure by excessive deflection transverse to thedirection of predominant loads.

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1.3.97 Stackability The ability of the fire protectionsystem to remain in place as the member deflects underload during a fire test.1.3.98 St~ffener An element used to retain or preventthe out-of-plane deformations of plates.1.3.99 Strain Deformation per unit length or unitangle.1.3.100 Strain Hardening The phenomenon ofincrease in stress with increase in strain beyondyielding.1.3.101 Strength Resistance to failure by yieldingor buckling.1.3.102 Strength Limir State A limit state of collapseor loss of structural integrity.1.3.103 Stress The internal force per unit area ofthe original cross-section,1.3.104 Stress Analysis The analysis of the internalforce and stress condition in an element, member orstructure.I.3.105 Stress Cycle Counting Sum of individualstress cycles from stress history arrived at using anyrational method.1.3.106 Stress Range Algebraic difference betweentwo extremes of stresses in a cycle of loading.1.3.107 Stress Spectrum Histogram of stress cyclesproduced by a nominal loading event design spectrum,during design life.1.3.108 Structural Adequacy for Fire The ability ofthe member to carry the test load exposed to thestandard fire test.1.3.109 Structural Analysis The analysis of stress,strain, and deflection characteristics of a structure.1.3.110 Strut A compression member, which maybe oriented in any direction.1.3.111 Sway The lateral deflection of a frame.1.3.112 Sway Member A member in which thetransverse displacement of one end, relative to the otheris not effectively prevented.1.3.113 Tensile Stress The characteristic stresscorresponding to rupture in tension, specified for thegrade of steel in the appropriate Indian Standard, aslisted in Table 1.1.3.114 Test Load The factored load, equivalent toa specified load combination appropriate for the typeof test being performed.

IS 800:20071.3.115 Transverse Direction atong the stronger axesof the cross-section of the member.1.3.116 Ultimate Limit State The state which, ifexceeded can cause collapse of a part or the whole ofthe structure.1.3.117 Ultimate Stress (see 1.3.113)1.3.118 Wind Loads Load experienced by memberor structure due to wind pressure acting on the surfaces.1.3.119 Yield Stress The characteristic stress of thematerial in tension before the elastic limit of thematerial is exceeded, as specified in the appropriateIndian Stwdard, as listed in Table 1.1.4 SymbolsSymbols used in this standard shall have the followingmeanings with respect to the structure or member orcondition. unless otherwise defined elsewhere in thisCode.

AACA.AC,A,A,A,,A,O

A,An,A,,CAn,

A,OA,,A,

A,A,,At,

Area of cross-sectionArea at root of threadsEffective cross-sectional areaReduced effective flange areaTotal flange areaGross cross-sectional areaGross cross-sectional area of flangeGross cross-sectional area ofoutstanding (not connected) leg of amemberNet area of the total cross-sectionNet tensile cross-sectional area of boltNet cross-sectional area of theconnected leg of a memberNet cross-sectional area of eachflangeNet cross-sectional area ofoutstanding (not connected) leg of amemberNominal bearing area of bolt on anyplate

Cross-sectional area of a bearing(load carrying) stiffener in contactwith the flange

Tensile stress area Gross cross-sectional area of a bolt

at the shank Gross sectional area in tension from

the centre of the hole to the toe ofthe angle section/channel section, etc(see 6.4) perpendicular to the line offorce

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IS 800:2007A,n

AvAv,

A,,

a, b

aOal

Bbb,beb,b,b,,b,b,b,b.ccm

Net sectional area in tension from the

Cn,y,CmzcCh

C,n

c,Ddd,

centre of the hole to the toe ofthe angle perpendicular to the lineof force (see 6.4)Shear areaGross cross-sectional area in shearalong the line of transmitted force(see 6.4)Net cross-sectional area in shearalong the line of transmitted force(se: 6.4 )Larger and smaller projection of theslab base beyond the rectanglecircumscribing the column,respectively (see 7.4)Peak accelerationUnsupported length of individualelements being laced between lacingpointsLength of side of cap or base plate ofa columnOutstand/width of the elementStiff bearing length, Stiffener bearinglengthEffective width of flange betweenpair of boltsWidth of the flangeWidth of flange as an internal elementWidth of flange outstandPanel zone width between columnflanges at beam-column junctionShear lag distanceWidth of tension fieldWidth of outstanding legCentre-to-centre longitudinaldistance of battensCoefficient of thermal expansionMoment amplification factor aboutrespective axesSpacing of transverse stiffenerMoment amplification factor forbraced memberMoment reduction factor for lateraltorsional buckling strengthcalculationMoment amplification factor forsway frameOverall depth/diameter of the cross-sectionDepth of web, Nominal diameterTwice the clear distance from the

d,dO

dPEE (~E (20)E,FcdwFdF.FOF,,,F~F,,,FlestF,~,,,,Ftest,MmFtesl, RFtest,sFWF,FXdff,f,Lk.J,c&(.fipbJ,,,

compression flange angles, plates ortongue plates to the neutral axis

Diameter of a bolt/ rivet hole Nominal diameter of the pipe column

or the dimensions of the column inthe depth direction of the base plate

Panel zone depth in the beam-columnjunction-

Modulus of elasticity for steelModulus of elasticity of steel at T CModulus of elasticity of steel at 20CModulus of elasticity of the panelmaterialBuckling strength of un-stiffenedbeam web under concentrated loadFactored design loadNormal forceMinimum proof pretension in highstrength friction grip bolts.Bearing capacity of load carryingstiffenerStiffener forceStiffener buckling resistanceTest loadLoad for acceptance testMinimum test load from the test tofailureTest load resistanceStrength test loadDesign capacity of the web in bearingExternal load, force or reactionBuckling resistance of load carryingweb stiffenerActual normal stress range for thedetail categoryFrequency for a simply supported oneway systemFrequency of floor supported on steelgirder perpendicular to the joistCalculated stress due to axial forceat service loadPermissible bending stress incompression at service loadPermissible compressive stress atservice loadPermissible bending stress in tensionat service loadPermissible bearing stress of the boltat service loadPermissible stress of the bolt in shearat service load

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.

1111

permissible tensile stress at service,oadPermissible tensile stress of the boltit service loadPermissible stress of the weld atservice loadActual bending stress at service loadActual bending stress in compressionat service loadDesign bending compressive stresscorresponding to lateral bucklingActual bearing stress due to bendingat service loadActual bending stress in tension atservice loadPermissible bending stress in columnbase at service loadActual axial compressive stress atservice loadElastic buckling stress of a column,Euler buckling stressDesign compressive stressExtreme fibre compressive stresscorresponding elastic lateral bucklingmomentEquivalent stress at service loadFatigue stress range corresponding to5 x 10 cycles of loadingEquivalent constant amplitude stressDesign normal fatigue strengthHighest normal stress rangeNormal fatigue stress rangeNormal stress in weld at service loadProof stressActual bearing stress at service loadActual bearing stress in bending atservice loadBearing strength of the stiffenersFrequencyActual shear stress in bolt at serviceloadActual tensile stress at service loadActual tensile stress of the bolt atservice loadCharacteristic ultimate tensile stressCharacteristic ultimate tensile stressof the boltAverage ultimate stress of thematerial as obtained from testCharacteristic ultimate tensile stressof the connected plate

ffWfwjf wfx&fy(nfy(20)f,,f,,f ym

f,,f,,f YwGg

hIIbhCheh,hih,h,h,I

Ifc

If,

I,

1,I,.

...

.

IS 800:2007Applied shear stress in the paneldesigned utilizing tension field actionActual stress of weld at service loadDesign stress of weld at service loadNominal strength of fillet weldMaximum longitudinal stress undercombined axial force and bendingCharacteristic yield stressYield stress of steel at T CYield stress of steel at 20CCharacteristic yield stress of boltCharacteristic yield stress of flangeAverage yield stress as obtained fromtestCharacteristic yield stress ofconnected plateCharacteristic yield stress of stiffenermaterialCharacteristic yield stress of the webmaterialModulus of rigidity for steelGauge length between centre of theholes perpendicular to the loaddirection, acceleration due to gravityDepth of the sectionTotal height from the base to the floorlevel concernedHeight of the columnEffective thicknessCenre-to-centre distance of flangesThickness of fire protection materialHeight of the lipStorey heightDistance between shear centre of thetwo flanges of a cross-sectionMoment of inertia of the memberabout an axis perpendicular to theplane of the frameMoment of inertia of the compressionflange of the beam about the axisparallel to the webMoment of inertia of the tensionflange of the beam about minor axisMoment of inertia of a pair ofstiffener about the centre of the web,or a single stiffener about the face ofthe webSecond moment of inertiaSecond moment of inertia of thestiffener about the face of the elementperpendicular to the web

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IS 800:2007[T

1,IwIVI,K,K,

KLKL(rKLJry

KLlrz

Transformed moment of inertia of theone way system (in terms ofequivalent steel, assuming theconcrete flange of width equal to the

.

(1Lr

-

KLr 16mm)9.810.912.911A22A33A456

s, 37S,42

{1vii) 1S2002 23

640 )660 )720 )940 )1 100)200220230250270280320350370dort

240-400260-390260-38033040042050052060080083090010401220370410430460490540620710740

2528322522.2012121098262524222120151310

r s 20220250>20 200240

360-440410-5002623

t t t/ A \ f v A \s16 >16 and >40 and >60 and >100 and 60 and >100 60S40 s60

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IS 800:2007Table 1 (Concluded)

SI Indian Grade/Classification PropertiesNo. StandardYieldStress UltimateTensile Stress Elongation,MPa, Min MPa, Min Pereent,Min

(1) (2) (3) (4) (5) (6)

\

E 165(Fe 290)E250(Fe410W)AE250(Fe 410 W)BE250(Fe 410 W)C

viii) IS2062 E 300 (Fe 440)E 350 (Fe 490)E 410 (Fe 540)E 450 (Fe 570) DE 450 (Fe 590) E

dort~l40165 165 165250 240 230250 240 230250 240 230300 290 280350 330 320410 390 380450 430 420450 430 420

dorr

290410410410440490540570590

232323232222202020

{1 s 25 >25 ands 50ix) 1s 3039 11 230 22011[ 400-490 22235 235 400-490235 22235 400-490 22

{Grade 1 240 350-450 25

~) IS6240 Grade 2 245 360-450 34f Annealed Condition 160 330-410 30

xi) Is 7557 t As-Drawn Condition I90 410-490 20

[HFC 210/CDS 210 330 202!OIERW21O

{HFC 240/CDSxii) IS 9295 2401ERW240

[HFC 310/CDS3Io/ERw31 o

240310

410 18450 15

{

1 170 290 302 210 330 28

xiii) 1S10748 3 240 410 254 275 430 205 310 490 15

NOTES1 Percentof elongation shall be taken overthe gauge length 5.65& where So= Original cross-sectional area of the test specimen.2 Abbreviations: O = Ordinary, D = Drawing, DD= DeepDrawing, EDD = Extra Deep Drawing.I) Stress at 0.2 percent non-proportional elongation,Min.

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conforming to IS 7557. They may also bemanufactured from steel conforming to IS 2062provided that the steel meets the requirements givenin IS 1148.2,3.2 Rivets shall conform to IS 1929 and IS 2155 asappropriate.2.3.3 High Tensile Steel RivetsHigh tensile steel rivets, shall be manufactured fromsteel conforming to IS 1149.2.4 Bolts, Nuts and WashersBolts, nuts and washers shall conform as appropriateto IS 1363 (Parts 1 to 3), IS 1364 (Parts 1 to 5), IS 1367(Parts 1 to 20), IS 3640, IS 3757, IS 4000, IS 5369,IS 5370, IS 5372, IS 5374, IS 5624, IS 6610, IS 6623,IS 6639, and IS 6649. The recommendations in IS 4000shall be followed.2.5 Steel CastingSteel casting shall conform to IS 1030 or IS 2708.2.6 Welding Consumable2.6.1 Covered electrodes shall conform to IS 814 orIS 1395, as appropriate.2.6.2 Filler rods and wires for gas welding shallconform to IS 1278.2.6.3 The supply of solid filler wires for submergedarc welding of structural steels shall conform toIS 1387.2.6.4 The bare wire electrodes for submerged arcwelding shall conform to IS 7280. The combinationof wire and flux shall satisfy the requirements ofIS 3613.2.6.5 Filler rods and bare electrodes for gas shieldedmetal arc welding shall conform to IS 6419 andIS 6560, as appropriate.2.7 Other MaterialsOther materials used in association with structural steelwork shall conform to appropriate Indian Standards.

SECTION 3GENERAL DESIGN REQUIREMENTS

3.1 Basis for Design3.1.1 Design ObjectiveThe objective of design is the achievement of anacceptable probability that structures will performsatisfactorily for the intended purpose duriug the designlife. With an appropriate degree of safety, they shouldsustain all the loads and deformations, during

IS 800:2007construction and use and have adequate resistance tocertain expected accidental loads and tire. Structureshould be stable and have alternate load paths to preventdisproportionate overall collapse under accidentalloading.3.1.2 Methods of Design3.1.2.1 Structure and its elements shall normally, bedesigned by the limit state method. Account should betaken of accepted theories, experimental informationand experience and the need to design for dumbi]ity.Calculations alone may not produce Safe, serviceableand durable structures. Suitable materials, qualitycontrol, adequate detailing and good supervision areequally important.3.1.2.2 Where the limit states method cannot beconveniently adopted; the working stress design (sef~Section 11) may be used.3.1.3 Design ProcessStructural design, including design for durability,construction and use should be considered as a whole.The realization of design objectives requirescompliance with clearly defined standards formaterials, fabrication, erection and in-servicemaintenance.3.2 Loads and Forces3.2.1 For the purpose of designing any element,member or a structure, the following loads (actions)and their effects shall be taken into account, whereapplicable, with partial safety factors find combinations(see 5.3.3):

a)b)

c)d)e)t]

g)

Dead loads;Imposed loads (live load, crane load, snowload, dust load, wave load, earth pressures,etc);Wind loads;Earthquake loads;Erection loads;Accidental loads such as those due to blast,impact of vehicles, etc; andSecondary effects due to contraction orexpansion resulting from temperaturechanges, differential settlements of thestructure as a whole or of its components,eccentric connections, rigidity of jointsdiffering from design assumptions.

3.2.1.1 Dead loads should be assumed in design asspecified in 1S 875 (Part 1).3.2.1.2 Imposed loads for different types of occupancyand function of structures shall be taken asrecommended in IS 875 (Part 2). Imposed loads arising

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IS 800:2007from equipment, such as cranes and machines shouldbe assumed in design as per manufacturers/suppliersdata (see 3.5.4). Snow load shall be taken as perIS 875 (Part 4).3.2.1.3 Wind loads on structures shall be taken as perthe recommendations of IS 875 (Part 3).3.2.1.4 Earthquake loads shall be assumed as per therecommendations of IS 1893 (Part 1).3.2.1.5 The erection loads and temperature effects shallbe considered as specified in 3.3 and 3.4 respectively.3.3 Erection LoadsAll loads required to be carried by the structure or anypart of it due to storage or positioning of constructionmaterial and erection equipment, including all loadsdue to operation of such equipment shall be consideredas erection loads. Proper provision shall be made,including temporary bracings, to take care of all stressesdeveloped during erection. Dead load, wind load andalso such parts of the live load as would be imposedon the stricture during the period of erection shall betaken as acting together with the erection loads. Thestructure as a whole and all parts of the structure inconjunction with the temporary bracings shall becapable of sustaining these loads during erection.3.4 Temperature Effects3.4.1 Expansion and contraction due to changes intemperature of the members and elements of a structureshall be considered and adequate provision made forsuch effect.3.4.2 The temperature range varies for differentlocalities and under different diurnal and seasonalconditions. The absolute maximum and minimumtemperatures, which may be expected in differentlocalities of the country, may be obtained from theIndian Metrological Department and used in assessingthe maximum variations of temperature for whichprovision for expansion and contraction has to be madein the structure.3.4.3 The range of variation in temperature of thebuilding materials may be appreciably greater or lesserthan the variation of air temperature and is influencedby the condition of exposure and the rate at which thematerials composing the structure absorb or radiateheat. This difference in temperature variations of thematerial and air shall be given due consideration. Theeffect of differential temperature within an element ormember, due to part exposure to direct sunlight shallalso be considered.3.4.4 The co-efficient of thermal expansion for steel isas given in 2.2.4 .l(e).

3,5 Load Combinations3.5.1 Load combinations for design purposes shall bethose that produce maximum forces and effects andconsequently maximum stresses and deformations.The following combination of loads with appropriatepartial safety factors (see Table 4) maybe considered.

a) Dead load + imposed load,b) Dead load + imposed load + wind or

earthquake load,c) Dead load + wind or earthquake load, andd) Dead load+ erection load.

NOTE In the case of structures supporting crmres, imposedloads shall include the crane effects as given in 3.5.4.3.5.2 Wind load and earthquake loads shall not beassumed to act simultaneously. The effect of each shallbe considered separately.3,5.3 The effect of cranes to be considered underimposed loads shall include the vertical loads,eccentricity effects induced by the vertical loads,impact factors, lateral (surge) and longitudinal(horizontal) thrusts, not acting simultaneously, acrossand along the crane rail, respectively [see 1S 875(Part 2)].3.5.4 The crane loads and their combinations to beconsidered shall be as indicated by the customer. Inthe absence of any specific indications, the loadcombinations shall be in accordance with theprovisions in IS 875 (Part 2) or as given below:

a)

b)

c)

d)

Vertical loads with full impact from oneloaded crane or two cranes in case of tandemoperation, together with vertical loads withoutimpact from as many loaded cranes as maybe positioned for maximum effect, along withmaximum horizontal thrust from one craneonly or two in case of tandem operation;Loads as specified in 3.5.4(a), subject tocranes in maximum of any two bays of thebuilding cross-section shaIl be considered formulti-bay multi-crane gantries;The longitudinal thrust on a crane track railshall be considered for a maximum of twoloaded cranes on the track; andLateral thrust (surge) and longitudinal thrustacting across and along the crane railrespectively, shall be assumed not to actsimultaneously. The effect of each force, shallhowever be investigated separately.

3.5.5 While investigating the effect of earthquakeforces, the resulting effect from dead loads of all cranesparked in each bay, positioned to cause maximum effectshall be considered.

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Table 2 Limiting Width to Thickness Ratio(Clauses 3.7.2 and 3.7.4)

. Compression Element

(1))utstandirig element ofcompressionflange

P

t--

Ifrl is negative:Webof an 1,1or box Generallyiwtion If r, is positive :

Axial compressionWebof a channel4ngle, compression due to bending (Both criteria should)e satisfied)$ingle angle, or double angles with the components;eparated, axial compression (All three criteria should be;atistied)lrtstanding leg of an angle in contact back-to-back in alouble angle memberoutstanding leg of an angle with its back in continuous:ontactwith another component$tem of a T-section, rolled or cut from a rolled I-or H-;ectionhular hollowtube, including welded tube subjected to:a) moment

b) axial compression

Ratio Class of SectionClass 1 Class2 Class3Plastic Compact Semi-compact

(2) (3) (4) (5)b/t~ 9.4& 10.5s 15.7Eb/If 8.4& 9.4& 13.6sb/tf 29.3s 33.5 & 42sb/ff Not applicableC2YCw 84& 105s 126z

105.0&dkq84E 1+< 126.0&1+~ 105$OC 1+ 2r*

dk+ but s 42E 1+1.5~ but 67E,where, b is the width of the element (may betaken as clear distance between lateral supports or between lateral support and free edge, as appropriate), t is the thickness ofelement, d is the depth of the web,D is the outer diameter of the element (see Fig. 2,3.7.3 and 3.7.4).4 Different elements of a cross-section can be in different classes. In such cases the section is classified based on the leastfavorable classification.5 The stress ratio r, and r~are defined as:

Actual average axial stress (negative if tensile)r, = Design compressive stress of web aloneActual average axial stress (negative if tensile)r2= Design compressive stress of ovedl section

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IS 800:2007The design of slender compression element (Class 4)considering the strength beyond elastic local bucklingof element is outside the scope of this standard.Reference may be made to IS 801 for such designprovisions. The design of slender web elements maybe made as given in 8.2.1.1 for flexure and 8.4.2.2 forshear,

tfCIEtwL-dROLLEDBEAMSANDCOLUMNS

SINGLEANGLES

t,

l---u

be b, f--ml

T

+dL ,t

tf

iEtwhLb

ROLLEDCHANNELS

r%?r-fdTt

TEES

3.7.4 Compound Elements in Built-up Section(see Fig. 2)In case of compound elements consisting of two ormore elements bolted or welded together, the limitingwidth to thickness ratios as given in Table 2 should beconsidered on basis of the following:

l-=---iudb-- mdRECTANGULAR CIRCULARHOLLOW HOLLOWSECTIONS SECTIONS

DOUBLEANGLES(BACKTO BACK)

t,

Tbltwl! BUILT-UPSECTIONSCOMPOUNDELEMENTSbi Internal Element Widthb, External Element WidthFIG. 2 DIMENSIONSOFSECTIONS

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IS 800:2007a) Outstanding width ofcompound element (b,)

to its own thickness.b) The internal width of each added plate

between the lines of welds or fastenersconnecting it to the original section to its ownthickness.

c) Any outstand of the added plates beyond theline of welds or fasteners connecting it tooriginal section to its own thickness.

3.8 Maximum Effective Slenderness RatioThe maximum effective slenderness ratio, KZlr valuesof a beam, strut or tension member shall not exceedthose given in Table 3. KL is the effective length ofthe member and r is appropriate radius of gyrationbased on the effective section as defined in 3.6.1.

Table 3 Maximum Values of EffectiveSlenderness Ratios

s} Member MaximumNo. EffectiveSlendernessRatio(KU-)(1) (2) (3)i)

ii)

iii)

iv)v)

vi)

A member carrying compressive loads 180resulting from dead loads and imposedloadsA tension member in which a reversal 180of direct stress occurs due to loads otherthan wind or seismic forcesA member subjected to compression 250forces resulting only from combinationwith wind/earthquake actions, providedthe deformation of such member doesnot adversely affect tbe stress in anypart of the structureCompression flange of a beam against 300lateral torsional bucklingA member normally acting m a tie in a 350roof truss or a bracing system notconsidered effective when subject topossible reversal of stress intocompression resulting from the actionof wind or earthquake forces]]Members always under tension) (other 400than pre-tensioned members)

I) Tension members, such as bracings, pre-tensioned to avoidsag, need not satisfy tbe maximum slenderness ratio limits.

3.9 Resistance to Horizontal Forces3.9.1 In designing the steel frame work of a building,provision shall be made (by adequate momentconnections or by a system of bracing) to effectivelytransmit to the foundations all the horizontal forces,giving due allowance for the stiffening effect of thewalls and floors, where applicable.3.9.2 When the walls, or walls and floors and/or roofs

20

are capable of effectively transmitting all the horizontalforces directly to the foundations, the structural steelframework may be designed without considering theeffect of wind or earthquake.3.9.3 Wind and earthquake forces are reversible andtherefore call for rigidity and strength under forcereversal in both longitudinal and transverse directions.To resist torsional effects of wind and earthquakeforces, bracings in plan should be provided andintegrally connected with the longitudinal andtransverse bracings, to impart adequate torsionalresistance to the structure.3.9.3.1 In shed type steel mill buildings, adequatebracings shall be provided to transfer the wind orearthquake loads from their points of action to theappropriate supporting members. Where theconnections to the interior columns or frames aredesigned such that the wind or earthquake loads willnot be transferred to the interior columns, theexterior columns or frames shall be designed to resistthe total wind or earthquake loads. Where theconnections to the interior columns and frames aredesigned such that the wind or earthquake effectsare transferred to the interior columns also, andwhere adequate rigid diaphragm action can bemobilized as in the case of the cast-in place RC slab,both exterior and interior columns and frames maybe designed on the assumption that the wind orearthquake load is divided among them in proportionto their relative stiffness. Columns also should bedesigned to withstand the net uplifting effect causedby excessive wind or earthquake. Additional axialforces arising in adjacent columns due to the verticalcomponent of bracings or due to frame action shallalso be accounted for.3.9.3.2 Earthquake forces are proportional to theseismic mass as defined in IS 1893. Earthquake forcesshould be applied at the centre of gravity of all suchcomponents of mass and their transfer to the foundationshould be ensured. Other construction details,stipulated in IS 4326 should also be followed.3.9.3.3 In buildings where high-speed traveling cranesare supported or where a building or structure isotherwise subjected to vibration or sway, triangulatedbracing or rigid portal systems shall be provided toreduce the vibration or sway to an acceptableminimum.3.9.4 FoundationsThe foundations of a building or other structures shallbe designed to provide the rigidity and strength thathas been assumed in the analysis and design of thesuperstructure.

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IS 800:20073.9.5 Eccentrically Placed LoadsWhere a wall, or other gravity load, is placedeccentrically upon the flange of a supporting steelbeam, the beam and its connections shall be designedfor torsion, unless the beam is restrained laterally insuch a way as to prevent the twisting of the beam.3.10 Expansion Joints3.10.1 In view of the large number of factors involvedin deciding the location, spacing and nature ofexpansion joints, the decision regarding provision ofexpansion joints shall be left to the discretion of thedesigner.3.10.2 Structures in which marked changes in plandimensions take place abruptly, shall be provided withexpansion joints at the section where such changesoccur. Expansion joints shall be so provided that thenecessary movement occurs with minimum resistanceat the joint. The gap at the expansion joint should besuch that:

a)

b)

It accommodates the expected expansioncontraction due to seasonal and durinalvariation of temperature, andIt avoids pounding of adjacent units underearthquake. The structure adjacent to the jointshould preferably be supported on separatecolumns but not necessarily on separatefoundations.

3.10.3 The details as to the length of a structure whereexpansion jdints have to be provided may bedetermined after taking into consideration variousfactors such as temperature, exposure to weather andstructural design. The provisions in 3.10.3.1 to 3.10.3.3are given as general guidance.3.10.3.1 If one bay of longitudinal bracing is provided

at the centre of the building or building section, thelength of the building section may be restricted to180 m in case of covered buildings and 120 m in caseof open gantries (see Fig. 3).

L--.-,,om~

ENDOF COVEREDBUILDING/SECTIONFIG. 3 MAXIMUMLENGTHOFBUILDINGWITHONE

BAYOFBRACING3.10.3.2 If more than one bay of longitudinal bracingis provided near the centre of the buildinglsection, themaximum centre line distance between the two linesof bracing may be restricted to 50 m for coveredbuildings (and 30 m for open gantries) and themaximum distance between the centre of the bracingto the nearest expansion jointiend of building or sectionmay be restricted to 90 m (60 m in case of opengantries). The maximum length of the building sectionthus may be restricted to 230 m for covered buildings(150 m for open gantries). Beyond this, suitableexpansion joints shall be provided (see Fig. 4).3.10.3.3 The maximum width of the covered buildingsection should preferably be restricted to 150 m beyondwhich suitable provisions for the expansion joint maybe made.3.10.4 When the provisions of these sections are metfor a building or open structure, the stress analysis dueto temperature is not required.

+ EXPANSIONJOINT

i

iii: Di90m 50m~ 90 m I

FIG. 4 MAXIMUMLENGTHOFBUILDING/SECTIONWITHTwo BAYSOFBRACINGS

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IS 800:2007SECTiON 4

METHODS OF STRUCTURAL ANALYSIS4.1 Methods of Determining Action Effects4.1.1 GeneralFor the purpose of complying with the requirementsof the limit states of stability, strength and serviceabilityspecified in Section 5, effects of design actions on astructure and its members and connections, shall bedetermined by structural analysis using the assumptionsof 4.2 and 4.3 and one of the following methods ofanalysis:

a)b)c)d)

Elastic analysis in accordance with 4.4,Plastic analysis in accordance with 4.5,Advanced analysis in accordance withAnnex B, andDynamic analysis in accordance with IS 1893(Part 1).

The design action effects for design basis earthquakeloads shall be obtained only by an elastic analysis. Themaximum credible earthquake loads shall be assumedto correspond to the load at which significant plastichinges are formed in the structure and thecorresponding effects shall be obtained by plastic oradvanced analysis. More information on analysis anddesign to resist earthquake is given in Section 12 andIS 1893 (Part 1).4.1.2 Non-sway and Sway FramesFor the purpose of analysis and design, the structuralframes are classified as non-sway and sway frames asgiven below:

a)

b)

c)

Non-sway frame One in which thetransverse displacement of one end of themember relative to the other end is effectivelyprevented. This applies to triangulated framesand trusses or to frames where in-planestiffness is provided by bracings, or by shearwalls, or by floor slabs and roof decks securedhorizontally to walls or to bracing systemsparallel to the plane of loading and bendingof the frame.Sway frame One in which the transversedisplacement of one end of the memberrelative to the other end is not effectivelyprevented. Such members and frames occurin structures which depend on flexural actionof members to resist lateral loads and sway,as in moment resisting frames.A rigid jointed multi-storey frame may beconsidered as a non-sway frame if in everyindividual storey, the deflection 6, over astorey height h,, due to the notional horizontal

loading given in 4.3.6 satisfies the followingcriteria:1) For clad frames, when the stiffening

effect of the cladding is not taken intoaccount in the deflection calculations:

65A 2 0002) For unclad frame or clad frames, when

the stiffening effect of the cladding istaken into account in the deflectioncalculations:

65A 40003) A frame, which when analyzed

considering all the lateral supportingsystem does not comply with the abovecriteria, should be classified as a swayframe. even if it is braced or otherwiselaterally stiffened.

4.2 Forms of Construction Assumed for StructuralAnalysis4.2.1 The effects of design action in the members andconnections of a structure shall be determined byassuming singly or in combination of the followingforms of construction (see 10.6.1).4.2.1.1 Rigid constructionIn rigid construction, the connections betweenmembers (beam and column) at their junction shall beassumed to have sufficient rigidity to hold the originalangles between the members connected at a jointunchanged under loading.4.2S.2 Semi-rigid constructionIn semi-rigid construction, the connections betweenmembers (beam and column) at their junction may nothave sufficient rigidity to hold the original anglesbetween the members at a joint unchanged, but shallbe assumed to have the capacity to furnish a dependableand known degree of flexural restraint. The relationshipbetween the degree of flexural restraint and the levelof the load effects shall be established by any rationalmethod or based on test results (see Annex F).4.2.1.3 Simple constructionIn simple construction, the connections betweenmembers (beam and column) at their junction will notresist any appreciable moment and shall be assumedto be hinged.4.2.2 Design of ConnectionsThe design of all connections shall be consistent with

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the form of construction, and the behaviour of theconnections shall not adversely affect any other partof the structure beyond what is allowed for in design.Connections shall be designed in accordance withSection 10.4.3 Assumptions in Analysis4.3.1 The structure shall be analyzed in its entiretyexcept as follows:

a)

b)

c)

Regular building structures, with orthogonalframes in plan, may be analyzed as a seriesof parallel two-dimensional sub-structures(part of a structure), the analysis being carriedout in each of the two directions, at rightangles to each other, except when there issignificant load redistribution between thesub-structures (part of a structure). Forearthquake loading three dimensional analysismay be necessary to account for effects oftorsion and also for multi-componentearthquake forces [see IS 1893 (Part 1)].For vertical loading in a multi-storey buildingstructure, provided with bracing or shear wallsto resist all lateral forces, each level thereof,together with the columns immediately aboveand below, may be considered as a sub-structure, the columns being assumed fixedat the ends remote from the level underconsideration.Where beams at a floor level in a multi-baybuilding structure tu-e considered as a sub-structure (part of a structure), the bendingmoment at the support of the beam due togravity loads may be determined based on theassumption that the beam is fixed at the i%end support, one span away from the spanunder consideration, provided that the floorbeam is continuous beyond that support point.

4.3.2 Spun LengthThe span length of a flexural member iu a continuousframe system shall be taken as the dlsiance betweencentre-to-centre of the supports.4.3.3 Arrangements of Imposed Loads in Bui[ding.sFor building structures, the various arrangements ofimposed loads considered for the analysis, shall includeat least the following:

a)b)

Where the loading pattern is fixed, thearrangement concerned.Where the imposed load is variable and notgreater than three-quarters of the dead load,the live load may be taken to be acting on allspans.

IS 800:2007c) Where the imposed load is variable and

exceeds three-quarters of the dead load,arrangements of live load acting on the floorunder consideration shall include thefollowing cases:1) Imposed load on alternate spans,2) Imposed load on two adjacent spans, and- 3) Imposed load on all the spans.

4.3.4 Base Sti@essIn the analysis of all structures the appropriate basestiffness about the axis under consideration shall beused. In the absence of the knowledge of the pedestaland foundation stiffness, the following may beassumed:

a)

b)

c)

d)

When the column is rigidly connected to asuitable foundation, the stiffness of thepedestal shall be taken as the stiffness of thecolumn above base plate. However in case ofvery stiff pedestals and foundations thecolumn may be assumed as fixed at base.When the column is nominally connectedto the foundation, a pedestal stiffness of10 percent of the column stiffness may beassumed.When an actual pin or rocker is provided inthe connection between the steel column andpedestal, the column is assumed as hinged atbase and the pedesrdl and foundation maybeappropriately designed for the reactions fromthe column.In case of (a) and (b), the bottom of thepedestal shall be assumed to have thefollowing boundary condition in the absenceof any derailed procedure based on theory ortests:1)

2)

3)

When the foundation consist of a groupof piles with a pile cap, raft foundationor an isolated footing resting on rock orvery hard soil, the pedestal shall beassumed to be fixed at the level of thebottom of footing or at the top of pilecap.When the foundation consist of anisolated footing resting on other soils,pedestal shall be assumed to be hingedat the level of the bottom of footing.When the pedestal is supported by asingle pile, which is laterally surroundedby soil providing passive resistance, thepile shall be assumed to be fixed at adepth of 5 times the diameter of the pile

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IS 800:2007below the ground level in case of compactground or the top level of compact soilin case of poor soil overlying compactsoil.

4) When the column is founded into rock,it may be assumed to be fixed at theinterface of the column and rock.

4.3.5 Simple ConstructionBending members may be assumed to have their endsconnected for shear only and to be free to rotate. Intriangulated structures, axial [orces maybe determinedby assuming that all members are pin connected. Theeccentricity for stanchion and column shall be assumedin accordance with 7.3.3.4.3.6 Notional Horizontal LoadsTo analyze a frame subjected to gravity loads,considering the sway stability of the frame, notionalhorizontal forces should be applied. These notionalhorizontal forces account for practical imperfectionsand should be taken at each level as being equal to 0.5percent of factored dead load plus vertical imposedloads applied at that level. The notional load shouldnot be applied along with other lateral loads such aswind and earthquake loads in the analysis.4.3.6.1 The notional forces should be applied on thewhole structure, in both orthogonal directions, in onedirection at a time, at roof and all floor levels or theirequivalent, They should be taken as actingsimultaneously with factored gravity loads.------ . . . . .4.3.6 ..4

a)b)c)d)

1he nohonal force should nOt be,applied when considering overturning oroverall instability;combined with other horizontal (lateral)loads;combined with temperature effects; andtaken to contribute to the net shear on thefoundation.

4.3.6.3 The sway effect using notional load undergantry load case need not be considered if the ratio ofheight to lateral width of the building is less than unity.4,4 Elastic Analysis4.4.1 AssumptionsIndividual members shall be assumed to remain elasticunder the action of the factored design loads for alllimit states.The effect of haunching or any variation of the cross-section along the axis of a member shall be considered,and where significant, shall be taken into account inthe determination of the member stiffness,

4.4.2 First-Order Elastic AnalysisIn a first-order elastic analysis, the equilibrium of theframe in the undeformed geometry is considered, thechanges in the geometry of the frame due to the loadingare not accounted for, and changes in the effectivestiffness of the members due to axial force areneglected. The effects of these on the first-orderbending moments shall be allowed for by using one ofthe methods of moment amplification of 4.4.3.2or 4.4.3.3 as appropriate. Where the momentamplification factor CY, CZ, calculated in accordancewith 4.4.3.2 or 4.4.3.3 as appropriate, is greater than1.4, a second-order elastic analysis in accordance withAnnex B shall be carried out.4.4.3 Second-Order Elastic Analysis4.4.3.1 The analysis shall allow for the effects of thedesign loads acting on the structure and its membersin their displaced and deformed configuration. Thesesecond-order effects shall be taken into account byusing eithe~

a) A first-order elastic analysis with momentamplification in accordance with 4.4.2,provided the moment amplification factors,C, and C, are not greater than 1.4; or

b) A second-order elastic analysis in accordancewith Annex B.

4.4.3.2 Moment amplification for members in non-swayframesFor a member with zero axial compression or a membersubject to axial tension, the design bending moment isthat obtained from the first order analysis for factoredloads, without any amplification.For a braced member with a design axial compressiveforce P~as determined by the first order analysis, thedesign bending moment shall be calculated consideringmoment amplification as in 9.3.2.2.4.4.3.3 Moment amplification for members in swayframesThe design bending moment shall be calculated as theproduct of moment amplification factor [see 9.3.2.2(C~Y, Cm,)] and the moment obtained from the firstorder analysis of the sway frame, unless analysisconsidering second order effects is carried out(see 4.4.3).4.4.3.4 The calculated bending moments from the firstorder elastic analysis may be modified by redistributionupto 15 percent of the peak calculated moment of themember under factored load, provided that:

a) the internal forces and moments in the

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members of the frame are in equilibrium withapplied loads.

b) all the members in which the moments arereduced shall belong to plastic or compactsection classification (see 3.7).

4.5 Plastic Analysis4.5.1 ApplicationThe effects of design action throughout or on part of astructure may be determined by a plastic analysis,provided that the requirements of 4.5.2 are met. Thedistribution of design action effects shall satisfyequilibrium and the boundary conditions.4.5.2 RequirementsWhen a plastic method of analysis is used, all of thefollowing conditions shall be satisfied, unless adequateductility of the structure and plastic rotation capacityof its members and connections are established for thedesign loading conditions by other means of evaluation:

a)

b)

c)

d)

e)

f)

$4

The yield stress of the grade of the steel usedshall not exceed 450 MPa.The stress-strain characteristics of the steelshall not be significantly different from thoseobtained for steels complying with IS 2062or equivalent and shall be such as to ensurecomplete plastic moment redistribution. Thestress-strain diagram shall have a plateau atthe yield stress, extending for at least six timesthe yield strain. The ratio of the tensilestrength to the yield stress specified for thegrade of the steel shall not be less than 1.2.The elongation on a gauge length complyingwith IS 2062 shall not be than 15 percent, andthe steel shall exhibit strain-hardeningcapability. Steels conforming to IS 2062 shallbe deemed to satisfy the above requirements.The members used shall be hot-rolled orfabricated using hot-rolled plates and sections.The cross-section of members not containingplastic hinges should be at least that ofcompact section (see 3.7.2), unless themembers meet the strength requirements fromelastic analysis.Where plastic hinges occur in a member, theproportions of its cross-section should notexceed the limiting values for plastic sectiongiven in 3.7.2.The cross-section should be symmetricalabout its axis perpendicular to the axis of theplastic hinge rotation.The members shall not be subject to impactloading, requiring fracture assessment or

IS 800:2007fluctuating loading, requiring a fatigueassessment (see Section 13).

4.5.2.1 RestraintsIf practicable, torsional restraint (against lateralbuckling) should be provided at all plastic hingelocations. Where not feasible, the restraint should beprovided within a distance of D/2 of the plastic hingelocation, where D is the total depth of section.The torsional restraint requirement at a section asabove, need not be met at the last plastic hinge to form,provided it can be clearly identified.Within a member containing a plastic hinge, themaximum distance L~ from the restraint at the plastichinge to an adjacent restraint should be calculated byany rational method or the conservative method givenbelow, so as to prevent lateral buckling.Conservatively L~ (ht mm) may be taken as

wheref=f, =Y =

Xt =A=

Iw, Iy, It =

actual compressive stress on the cross-section due to axial load, in N/mm*;yield stress, in N/mm2;radius of gyration about the minor axis, inmm;torsional index, x, =1.132 (Alw/IylJ05;area of cross-section; andwarping constant, second moment of thecross section above the minor axes andSt. Venants torsion constant, respectively.

Where the member has unequal flanges, rYshould betaken as the lesser of the values of the compressionflange only or the whole section.Where the cross-section of the member varies withinthe length L~, the maximum value of rY and theminimum value of xl should be used.The spacing of restraints to member lengths notcontaining a plastic hinge should satisfy therecommendations of section on lateral bucklingstrength of beams (see 8.2.2). Where the restraints areplaced at the limiting distance L~, no further checksare required.4.5.2.2 Stiffeners at plastic hinge locationsWeb stiffeners should be provided where a concentratedload, which exceeds 10 percent of the shear capacity

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IS 800:2007of the member, is applied within D\2 of a plastic hingelocation (see 8.2.1.2). The stiffener should be providedwithin a distance of half the depth of the member oneither side of the hinge location and be designed tocarry the applied load in accordance with 8.7.4. If thestiffeners are flat plates, the outstand width to thethickness ratio, b/t, should not exceed the values givenin the plastic section (see 3.7, Table 2). Where other

[)I msections are used the ratio ~It should not exceed

the values given for plastic section (for simple outstand,as in 3.7);whereIso = second moment of area of the stiffener about

the face of the element perpendicular to theweb; and

I, = St. Venants torsion constant of the stiffener.4.5.2.3 The frame shall be adequately supported againstsway and out-of-plane buckling, by bracings, momentresisting frame or an independent system such as shearwall.4.5.2.4 Fabrication restrictionWithin a length equal to the member depth, on eitherside of a plastic hinge location, the followingrestrictions should be applied to the tension flange andnoted in the design drawings. Holes if required, shouldbe drilled or else punched 2 mm undersize and reamed.All sheared or hand flame cut edges should be finishedsmooth by grinding, chipping or planning.4.5.3 Assumptions inAnalysisThe design action effects shall be determined using arigid-plastic analysis.It shall be permissible to assume full strength or partialstrength connections, provided the capacities of theseare used in the analysis, and provided that

a) in a full strength connection, the momentcapacity of the connection shall be not lessthan that of the member being connected;

b) in a partial strength connection, the momentcapacity of the connection may be less thanthat of the member being connected; andc) in both cases the behaviour of the connectionshall be such as to allow all plastic hingesnecessary for the collapse mechanism todevelop, and shall be such that the requiredplastic hinge rotation does not exceed therotation capacity at any of the plastic hingesin the collapse mechanism.

In the case of building structures, it is not normallynecessary to consider the effect of alternating plasticity.4.5.4 Second-Order Elastic AnalysisAny second-order effects of the loads acting on thestructure in its deformed configuration may beneglected, provided the following are satisfied:

a)

b)

For clad frames, provided the stiffening effectsof masonry infill wall panels or diaphragms ofprofiled wall panel is not taken into account,and where elastic buckling load factor, JC,(see 4.6) satisfies J,jAP> 10.[f10>2C{IP24,6 the second-order effects maybe considered by ampli~ing the design loadeffects obtained from plastic analysis by afactor 6,= {0.9 2,, /( 2=,- l)}.If ACjJP < 4.6, second-order elasto-plasticanalysis or second-order elastic analysis(see 4.4.3) is to be carried out.For un-clad frames or for clad frames wherethe stiffening effects of masonry infill or dia-phragms of profiled wall panel is taken intoaccount, where elastic buckling load factor, 2 AC]AP5.75 the second-order effectsmay be considered by ampli~ing the designload effects obtained from plastic analysis bya factor iSP={0.9 2,,/( J,,I)}.If IC{ LP

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fC~is the axial compressive stress in the column fromthe factored load analysis.4.6.2.2 Regular sway framesIn a rectangular sway frame with regular loading andnegligible axial forces in the beams, the buckling load,PC,,,for each column shall be determined as P,, =A~CwherefCCs the elastic buckling stress of the column inthe plane of frame, obtained in accordance with 7.1.2.1.The elastic buckling load factor AC,,or the whole frameshall be taken as the lowest of all the ratios, k,,,,calculated for each storey of the building, as givenbelow:

whereP=L=

~ _ ~(PCC/L)c - ~(P/L)

member axial force from the factored loadanalysis, with tension taken as negative; andcolumn length and the summation includesall columns in the plane frame within astorey.

SECTION 5LIMIT STATE DESIGN

5.1 Basis for Design5.1.1 In the limit state design method, the structureshall be designed to withstand safely all loads likely toact on it throughout its life. It shall not suffer totalcollapse under accidental loads such as from explosionsor impact or due to consequences of human error to anextent beyond the local damages. The objective of thedesign is to achieve a structure that will remain fit foruse during its life with acceptable target reliability. Inother words, the probability of a limit state beingreached during its lifetime should be very low. Theacceptable limit for the safety and serviceabilityrequirements before failure occurs is called a limit state.In general, the structure shall be designed on the basisof the most critical limit state and shall be checked forother limit states.5.L2 Steel structures are to be designed and constructedto satisfy the design requirements with regard tostability, strength, serviceability, brittle fracture,fatigue, fire, and durability such that they meet thefollowing:

a) Remain fit with adequate reliability and beable to sustain all actions (loads) and otherinfluences experienced during constructionand use;

b) Have adequate durability under normalmaintenance;

c) Do not suffer overall damage or collapse

IS 800:2007disproportionately under accidental eventslike explosions, vehicle impact or due toconsequences of human error to an extentbeyond local damage. The potential forcatastrophic damage shall be limited oravoided by appropriate choice of one or moreof the following:1) Avoiding, eliminating or reducing

exposure to hazards, which the structureis likely to sustain.

2) Choosing structural forms, layouts anddetails and designing such that:i) the structure has low sensitivity to

hazardous conditions; andii) the structure survives with only local

damage even after serious damageto any one individual element by thehazard.

3) Choosing suitable material, design anddetailing procedure, constructionspecifications, and control procedures forshop fabrication and field construction asrelevant to the particular structure.

The following conditions may be satisfied to avoid adisproportionate collapse:

a) The building should be effectively tiedtogether at each principal floor level and eachcolumn should be effectively held in positionby means of continuous ties (beams) nearlyorthogonal, except where the steel worksupports only cladding weighing not morethan 0.7 kN/m~ along with imposed and windloads. These ties must be steel members suchas beams, which may be designed for otherpurposes, steel bar reinforcement anchoringthe steel frame to concrete floor or steel meshreinforcement in composite slab with steelprofiled sheeting directly connected to beamwith shear connectors. These steel ties andtheir end connections should be capable ofresisting factored tensile force not less thanthe factored dead and imposed loads actingon the floor area tributary to the tie nor lessthan 75 kN. Such connection of ties to edgecolumn should also be capable of resisting1 percent of the maximum axial compressionin the column at the level due to factored deadand imposed loads. All column splices shouldbe capable of resisting a tensile force equalto the largest of a factored dead and live loadreaction from a single floor level locatedbetween that column splice and the nextcolumn splice below that splice. Lateral loadsystem to resist notional horizontal loadsprescribed in 4.3.6 should be distributed

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IS 800:2007

b)

c)

throughout the building in nearly orthogonaldirections so that no substantial portions isconnected at only one point to such a system.Precast concrete or other heavy floor or roofunits should be effectively anchored in thedirection of their span either to each other overthe support or directly to the support.Where the above conditions to tie the columnsto the floor adequately are not satisfied eachstorey of the building should be checked toensure that disproportionate collapse wouldnot precipitate by the notional removal, oneat a time, of each column.Where each floor is not laterally supportedby more than one system, check should bemade at each storey by removing one suchlateral support system at a time to ensure thatdisproportionate collapse would not occur.The collapse is considered disproportionate,if more than 15 percent of the floor or roofarea of 70 mzcollapse at that level and at oneadjoining level either above or below it, undera load equal to 1.05 or 0.9 times the dead load,0.33 times temporary or full imposed load ofpermanent nature (as in storage buildings) and0.33 times wind load acting together.

5.1.3 Structures designed for unusual or specialfunctions shall comply with any other relevantadditional limit state considered appropriate to thatstructure.5.1.4 Generally structures and elements shall bedesigned by limit state method. Where limit statemethod cannot be conveniently adopted, working stressdesign (see Section 11) may be used.5.2 Limit State Design5.2.1 For achieving the design objectives, the designshall be based on characteristic values for materialstrengths and applied loads (actions), which take intoaccount the probability of variations in the materialstrengths and in the loads to be supported. Thecharacteristic values shall be based on statistical data,if available. Where such data is not available, theseshall be based on experience. The design values arederived from the characteristic values through the useof partial safety factors, both for material strengths andfor loads. In the absence of special considerations, thesefactors shall have the values given in this sectionaccording to the material, the type of load and the limitstate being considered. The reliability of design isensured by satisfying the requirement:

Design action S Design strength5.2.2 Limit states are the states beyond which the structure

no longer satisfies the performance requirementsspecified. The limit states are classified as:

a) Limit state of strength; andb) Limit state of serviceability. t

5.2.2.1 The limit states of strength are those associatedwith failures (or imminent failure), under the action ofprobable and most unfavorable combination of loadson the structure using the appropriate partial safetyfactors, which may endanger the safety of life andproperty. The limit state of strength includes:

a) Loss of equilibrium of the structure as a wholeor any of its parts or components.

b) Loss of stability of the structure (includingthe effect of sway where appropriate andoverturning) or any of its parts includingsupports and foundations.

c) Failure by excessive deformation, rupture ofthe structure or any of its parts or components,

d) Fracture due to fatigue,e) Brittle fracture.

5.2.2.2 The limit state of serviceability include:a)

b)

c)d)e)

Deformation and deflections, which mayadversely affect the appearance or effectiveuse of the structure or may cause improperfunctioning of equipment or services or maycause damages to finishes and non-structuralmembers.Vibrations in the structure or any of itscomponents causing discomfort to people,damages to the structure, its contents or whichmay limit its functional effectiveness. Specialconsideration shall be given to systemssusceptible to vibration, such as large openfloor areas free of partitions to ensure thatsuch vibrations are acceptable for the intendeduse and occupancy (see Annex C).Repairable damage or crack due to fatigue.Corrosion, durability.Fire.

5.3 ActionsThe actions (loads) to be considered in design includedirect actions (loads) experienced by the structure dueto self weight, external actions etc., and imposeddeformations such as that due to temperature andsettlements.5.3.1 Classification ofActionsActions are classified by their variation with time asgiven below:

a) Permanent actions (Q ): Actions due to self-!eight of structura and non-structural

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b)

c)

components, fittings, ancillaries, and fixedequipment, etc.Variable actions (Qv): Actions due toconstruction and service stage loads such asimposed (live) loads (crane loads, snow loads,etc.), wind loads, and earthquake loads, etc.Accidental actions (Q,): Actions expected dueto explosions, and impact of vehicles, etc.

5.3.2 Characteristic Actions (Loads)5.3.2.1 The Characteristic Actions, QC,are the valuesof the different actions that are not expected to beexceeded with more than 5 percent probability, duringthe life of the structure and they are taken as:

a)

b)

c)

d)

the self-weight, in most cases calculated onthe basis of nominal dimensions and unitweights [see 1S 875 (Part 1)].the variable loads, values of which arespecified in relevant standard [see IS 875 (allParts) and IS 1893 (Part l)].the upper limit with a specified probability(usually 5 percent) not exceeding during somereference period (design life).specified by client, or by designer inconsultation with client, provided they satisfythe minimum provisions of the relevantloading standard.

5.3.2.2 The characteristic values of accidental loadsgenerally correspond to the value specified by relevantcode, standard or client. The design for accidental load

LS 800:2007is generally not required in building unless it is requiredby client or approving authority in which case,generally recommendation in 5.1.2 c) or specialistliterature shall be followed.5.3.3 Design ActionsThe Design Actions, Q~, is expressed as Qd = ~?. Q,k

kwhere

yk = partial safety factor for different loads k,given in Table 4 to account for:a) Possibility of unfavorable deviation of

the load from the characteristic value,b) Possibility of inaccurate assessment of

the load,c) Uncertainty in the assessment of effects

of the load, andd) Uncertainty in the assessment of the

limit states being considered.The loads or load effects shall be multiplied by therelevant ~f factors, given in Table 4, to get the designloads or design load effects.5.4 StrengthThe ultimate strength calculation may requireconsideration of the following:

a) Loss of equilibrium of the structure or anypart of it, considered as a rigid body; and

b) Failure by excessive deformation, rupture or

Table 4 Partial Safety Factors for Loads, y~,for Limit States(Clauses 3.5.1 and 5.3.3)

Combination Limit State of Strength Limit State of ServiceabilityF Y 7 ~ L

T & mLeading Accompanying Accompanying

(1) (2) (3) (4) (5) (6) (7) (8) (9) (lo)DL+LL+CL 1.5 1.5 1.05 1.0 1.0 1.0 DL+LL+CL+ 1.2 1.2 1.05 0.6 1.0 0.8 0.8 0.8WLJEL 1.2 1.2 0.53 1.2DL+WLfEL 1.5(0.9)2 1.5 1.0 1.0DL+ER 1.2 ~~;)z)DL+LL+AL 1.0 0.35 0.35 1.0 )When action of different live loads is simultaneously considered, the leading live load shall be considered to be the one causing thehigher loadeffects in the member/section.)This value is to be considered when the dead load contributes to stability against overturning is critical or the dead load causesreduction in stress due