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INTERNATIONAL JOURNAL and Technology (IJCIET), ISSN 0976 – 6308 International Journal of Civil Engineering OF CIVIL ENGINEERING AND TECHNOLOGY July-August (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, (IJCIET) (2013), © IAEME ISSN 0976 – 6308 (Print) ISSN 0976 – 6316(Online) IJCIET Volume 4, Issue 4, July-August (2013), pp. 36-54 © IAEME: www.iaeme.com/ijciet.asp Journal Impact Factor (2013): 5.3277 (Calculated by GISI) © IAEME www.jifactor.com A CRITICAL COMPARATIVE STUDY OF IS:800-2007ANDIS:800-1984 Dr.T.Muralidhara Rao1, S.S.Phani2 1 Professor, Dept.of Civil Engg., CVR College of Engineering, Hyderabad 2 Deputy Executive Engineer, Tirumala Tirupati Devasthanam, Hyderabad. ABSTRACT Now-a-days, the whole world is changing over to limit state method since it is more rational. The latest version of the Code of Practice for general construction in steel IS: 800-2007 is based on Limit State Method of design. The design concept is totally changed in comparison to earlier code IS 800:1984 which is based on Elastic method. In view of this, an effort has been made to high light the critical comparison between the important clauses of IS:800-2007 and IS:800-1984. At a glance, the present study will provide the readers a quick and clear idea about the changes in the corresponding clauses of old(IS:800-1984) and new (IS:800-2007) codes of practice. Keywords: IS 800:1984, IS 800: 2007, Critical Comparison, Limit state method, Working stress method. INTRODUCTION Codes of practice provide the minimum requirements that a design has to satisfy. In India, Bureau of Indian Standards (B.I.S.) is the statutory body that publishes the codes of practice to be followed in the Indian Professional practice. Though the codes of practices issued by B.I.S. are revised after 20 to 25 years, the second revision of IS 800 was published in 1984. The third revision of the code was released after about 24 years, in December 2007, by the B.I.S. The material contained in the code reflects the state-of-the-art of knowledge and is based on the provisions in other international codes as well as other research publications. This version of the code is based on the Limit state method of design philosophy whereas the earlier version was based on Working stress method. The revised Code IS:800-2007 will enhance the confidence of designers, engineers, contractors, technical institutions, professional bodies and the industry will open a new era in safe and economic construction in steel. 36 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, July-August (2013), © IAEME MAJOR MODIFICATIONS In the latest revision of IS: 800, the following major modifications have taken place: a) The standard is based on limit state method, reflecting the latest developments and the state of the art. b) In view of the development and production of new varieties of medium and high tensile structural steels in the country, the scope of the standard has been modified permitting the use of any variety of structural steel provided the relevant provisions of the standard are satisfied. c) The standard has made reference to the Indian Standards now available for rivets, bolts and other fasteners. Codal Provisions The code is divided into the following 17 Sections. It also contains seven appendices. a) Contents 1. General 2. Materials 3. General Design Requirements 4. Methods of Structural Analysis 5. Limit State Design 6. Design of Tension Members 7. Design of Compression Members 8. Design of Members subjected to Bending 9. Member subjected to combined forces 10. Connections 11. Working Stress Design 12. Design and Detailing for Earthquake Loads 13. Fatigue 14. Design Assisted by Testing 15. Durability 16. Fire Resistance 17. Fabrication and Erection b) It also includes the following Annexure A: List of referred Indian Standards B: Analysis and design methods C: Design against floor vibration D: Determination of effective length of columns E: Elastic lateral torsional buckling F: Connections G: General recommendations for Steelwork Tenders and Contracts H: Plastic properties of beams c) General Design Requirement • The new edition of IS: 800 clearly classify cross sections as to, Plastic, Compact, Semi- Compact or Slender. Separate design procedures have been laid down for each type of classification. • The classification has been made based on each element of the section involved and depends on the ratio of the major and minor dimension of the element i.e., limiting width to thickness ratio. d) Limit States Method of Design • Separate Partial Safety Factors for different loads and combinations are considered based on the probability of occurrence of the loads. Similarly different safety factors for materials are also considered depending on perfection in material characteristics and fabrication/ erection tolerances. • Different permissible deflections considering different material of construction have also been proposed. e) Tension Members • Tension members have been designed by considering not only failure of the net cross section (after taking Shear Lag) but also considering yielding of the gross cross section and rupture of the section at the joint. f) Compression Members • Design of Compression members considers the appropriate buckling curve out of total four numbers depending on the type of section and the axis of buckling. Earlier version of the 37 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, July-August (2013), © IAEME Working Stress Method of design considered only one buckling curve for all types of members irrespective of the nature of buckling. g) Members Subjected To Bending • Reduction in Flexure capacity due to high Shear Force has been elaborated in detail. • New version introduces tension field design of plated steel girders. h) Members Subjected To Combined Forces • Moment Gradient across a member / element considered in detail, while designing against combined action of axial force and bending moment in an element of a structure. i) Working Stress method of Design • Working Stress Method (WSM) of Design has been kept in a separate chapter with minor modifications (compared to the earlier code) and in tune with the specifications of the new code to ensure smooth transition from WSM to LSM for Practicing engineers and Academicians whosoever desires. j) Design Against Fatigue • Design against fatigue has been introduced for the first time. The state-of-art concept of stress range has been introduced for the first time in this code, this code automatically supersedes IS:1024 for steel structures which considered the stress–ratio method. k) Earthquake Resistance • Response Reduction factor has been introduced and elaborated in the new edition for the first time. • Comparing the provisions of the 1984 version of the code with that of the present code, it is seen that the present code contains major revisions. Comparison of Critical Parameters/Clauses of IS:800-2007 and IS: 800-1984 In the newly revised IS: 800, stress is laid to make optimum utilisation of the structural member along with provision of making adequate checks for restricting local buckling. Comparison of the critical parameters/clauses of two versions of the code (i.e. IS: 800-2007 and IS: 800-1984) is as follows: S.No. Clause IS:800-2007 IS:800-1984 Comments 1.0 Material 1.1 Structural Table-1(Pg.14) Clause: 2.1(Pg.21) Steels All the structural steels used All structural steels used in No change. in general construction, general construction coming under the purview coming under the purview of this standard shall of this coded shall confirm conform to IS:2062 before to IS:2062, before fabrication. fabrication. Structural steel other than Structural steel other than that specified in IS 2062 can those specified in be used provided that the clause:2.1 may also be permissible stresses and used provided that the other design provisions are permissible stresses and suitably modified and the other design provisions are steel is also suitable for the suitably modified and steel type of fabrication adopted. is also suitable for the type of fabrication adopted. 38 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, July-August (2013), © IAEME 1.2 Fasteners / Clause 2.3,Pg.12-15 Clause:2.2,2.5,2.6,Pg.21- Rivets/ 22 --- Bolts/Nuts Rivets made from steel shall Rivets shall conform to conform to IS:7557 or 2062 IS:1929-1961 and as appropriate. High IS:2155-1962 as Tension Steel rivets shall appropriate. High tension conform to IS:1149. steel rivets, if used, shall me manufactured from steel conforming to Bolts, Nuts and Washers IS:1149. shall conform to the Bolts, Nuts shall conform recommendations of IS: to IS:1363-1967, IS:1364- 4000. 1967, IS:1367-1967, IS:3640-1967, IS:3757- 1972, IS:6623-1972 and IS:6639-1972 as appropriate. Washers shall conform to IS:5369-1975, IS:5370-1969, IS:5372- 1975, IS:5374-1975, IS:6610-1972 and IS:6649-1972 as appropriate. 2.0 General Design Requirements 2.1 Load Clause:3.5(Pg.16) Clause:3.4.2(Pg.24) Combination 1) DL + IL 1) DL + IL Importance 2) DL+ IL + WL or EL 2) DL+IL+WL or EL is also given 3) DL + WL or EL 3) DL + WL or EL to the 4) DL + ERL erection DL-Dead Load DL-Dead Load loading in IL-Imposed Load IL-Imposed Load deciding WL-Wind Load WL-Wind Load critical load EL-Earthquake Load EL-Earthquake Load combination. ERL-Erection Load 2.2 Section Clause:3.7(Pg.17) Classification Sections are classified based No such classification has The Class of on its local buckling been made. section strength and the ability to governs its allow rotation before failing. design. They are a) Class 1 (Plastic) b) Class 2 (Compact) c) Class 3(Semi-compact) d) Class 4 (Slender) 39 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, July-August (2013), © IAEME 2.3 Increase of Clause:5.3.3(Pg.29) Clause:3.9(Pg.31) Stresses Partial safety factors have to If Wind / Earthquake Partial safety be considered and no Loads are considered, factors are increase or decrease of permissible stresses in considered stresses have to be structural steel and steel for loads considered for individual castings shall be increased instead of loads. by 33.33%. increasing the If Wind / Earthquake permissible Loads are considered, stresses. permissible stresses in rivets, bolts and nuts shall be increased by25%. Clause:5.5.1(Pg.30) Clause:3.12(Pg.34) 2.4 Stability Structure should satisfy two Restoring moment>1.2 Importance limit states xmax. Overturning is given to 1. Limit state of strength moment(due to DL) + 1.4 serviceability 2. Limit state of times max. Overturning requirements serviceability moment (due to IL and in deciding The structure should adhere WL/EL) structures toa) Stability against stability in Overturning. In cases where DL addition to The loads and effects provides the restoring the strength Contributing to the moment, only 0.9 times requirement. resistance shall be DL shall be considered. multiplied with 0.9 and added together to get design resistance (after multiplying with appropriate partial safety factor). b) Sway Stability. 2.5 Limiting Clause:5.6.1(Pg.31) Clause:3.13(Pg.34) Deflection Deflection limits have been Max. Deflection for all Importance provided separately for applicable loads (Vertical is given to Industrial buildings and / Horizontal ) = l / 325 of serviceability other buildings and separate the span. requirements limits have been mentioned for various for different members. members in a structure. 3.0 Tension Members 3.1 Axial Clause:6.1(Pg.32-34) Clause:4.1(Pg.37) Stresses Design strength of a tension Stress on the net effective Additional member should be least of area not to exceed provision *Strength due to yielding σ at = 0.6 f y (MPa). for block of gross c/s shear has *Strength due to rupture of been critical c/s incorporated. *Strength due to block shear 40 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, July-August (2013), © IAEME 3.2 Maximum Clause:3.8(Pg.20) Clause:3.7,Table No change. Slenderness *Tension member(other 3.1(Pg.30) Ratio than pre-tensioned) = 400 *Tension member (other *Tension Member =180 than pre-tensioned)= 400 (reversal of stress due to *Tension Member = 180 loads other than WL or EL) (reversal of stress due to *Tension member = 350 loads other than WL or (reversal of stress due to EL) WL or EL) *Tension member = 350(reversal of stress due to WL or EL) 3.3 Design Clause:6.2,6.3&6.4(Pg.32- Clause:4.2(Pg.37) Partial safety strength and 34) Design strength P = σ at Anet factors have net effective Design strength shall be Single angle connected introduced. area minimum of Tdg , Tdn , Tdb . through one leg: Where, Anet = A1 + A2 k , where, Tdg =Strength in axial 3 A1 k= tension governed by 3 A1 + A2 yielding of gross section Pair of angles(single tee) = Ag f y γ m 0 back-to-back connected by Tdn =Strength of plate in one leg of each angle to axial tension governed by the same side of a gusset: rupture of net cross Anet = A1 + A2 k , where, sectional area at holes 5 A1 k= = 0.9 An f u γ ml 5 A1 + A2 Tdn =Rupture strength of an angle connected through Double angles or tees one leg governed by rupture back-to-back connected to at net section each side of a gusset : = 0.9 Anc f u γ ml + β Ago f y γ m 0 If the angles are connected by tacking rivets along their length at a pitch not Tdb = strength of connection exceeding 1.0m, then the governed by block shear at effective area shall be an end connection of plates taken equal to the gross and angles= area minus the deduction [ Avg f y ( 3 γ m0 ) + 0.9Atn fu γ ml ] for holes. (OR) Double angles or tees back-to-back connected to Tdb =[0.9A fu ( 3γml ) + A fy γm0] vn tg each side of a gusset : If the angles are not tack Where, riveted using a pitch not f y = yield stress of material exceeding 1.0m, then each Ag =gross area of cross angle shall be designed as a single angle connected Section through one leg and γ m0 =partial safety factor for effective sectional area 41 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, July-August (2013), © IAEME failure in tension by shall be calculated using yielding=1.10 Anet = A1 + A2 k , where, γ ml =partial safety factor for 3 A1 failure at ultimate k= 3 A1 + A2 stress=1.25 f u = ultimate stress of the material Where A1 =Effective cross Anc = net area of the sectional area of connected connected leg leg (or flange of tee) Ago = gross area of the A2 = Gross area of outstanding leg outstanding leg (or web of β =1.4−0.076(wt)(ft fu)(bs L ) ≤(fuγm0 fyγml ) the tee) c ≥ 0.7 Where, w = outstand leg width bs = shear leg width Lc = length of the end connection(i.e., distance between outermost bolts in the end joint measured along the load direction or length of the weld along the load direction) Avg , Avn = minimum gross and net area in shear along bolt line parallel to external force respectively Atg , Atn = minimum gross and net area in tension from the bolt hole to the toe of the angle, end bolt line, perpendicular to the line of force respectively. 4.0 Compression Members 4.1 Design Clause:7.1.2 (Pg.34) Clause:5.1.1, IS:800-2007 Partial safety strength Design compressive Design strength, factors and strength, Pd = Ac f cd Pd = Agσ ac ≤ 0.6 f y nor imperfection factors (based Where, Ac = effective the permissible stress σ ac on buckling sectional area (i.e., gross Where, Ag = gross class) have sectional area-deduction for sectional been rivets/bolts holes area) Area introduced f cd =design compressive f cc f y for design Stress = σ ac = 0.6 n compressive [( f cc ) + ( f y ) ]1/ n n f y γ m0 stress. f cd = = χ fy γ m ≤ fy γm φ + [φ 2 − λ 2 ]0.5 42 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, July-August (2013), © IAEME Where, Where, σ ac =permissible stress in φ = 0.5[1 + α (λ − 0.2) + λ 2 ] axial compression(MPa) λ = non-dimensional f y =yield stress of steel effective (MPa) slenderness ratio f cc =elastic critical stress 2 = f y f cc = f y ( KL r ) π 2 E π 2E f cc = Euler buckling stress in compression = λ2 = π 2 E ( KL r ) 2 E =modulus of elasticity of Where, steel ( 2 × 105 MPa ) KL r =effective slenderness λ = ( l r ) =slenderness ratio or ratio of effective length, KL to appropriate ratio radius of gyration, r of the member α =imperfection factor n =a factor assumed as 1.4 =0.21 for buckling class ‘a’ =0.34 for buckling class ‘b’ =0.49 for buckling class ‘c’ =0.76 for buckling class ‘d’ χ =stress reduction factor (Table 8, IS:800-2007) for different buckling class, slenderness ratio and yield stress 0.5 = 1 [φ + (φ 2 − λ 2 ) ] 4.2 Axial Clause:7.1.2.1(Pg.34) Clause:5.1(Pg.38) stresses Allowable axial stress or Direct stress in Concept of design compressive stress compression shall not imperfection (fcd) shall be calculated exceed 0.6fy or as factor and using the formulas given in calculated by equation buckling the clause or can be given in Cl. 5.1.1. class of the calculated using Tables Permissible stress σ ac shall section has 9(a),9(b),9(c),9(d) on the be taken from Table- been basis of buckling class of 5.1(Pg.39) for introduced. the section. corresponding slenderness ratio. 4.3 Effective Clause:7.2(Pg.35-45) Clause:5.2(Pg.38) Length (l), ‘K’ values shall be taken ‘K’ values shall be taken ‘K’ values l = KL appropriately based on appropriately based on given in both degree of end restraint of degree of end restraint of the codes are member as given in Table- member as given in Table- same. 11(Pg.45). 5.2 (Pg.41&42) or follow 43 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, July-August (2013), © IAEME the procedure given in Appendix-C. Trusses and braced frames Trusses and braced frames buckling in the plane of buckling in the plane of truss, effective length ‘1’ truss, ‘l’ shall be taken as shall be taken as between between 0.7 and 1.0 times 0.7 and 1.0 times the the distance between the distance between the centres centres of intersections, of intersections, depending on degree of depending on degree of end end restraint. restraint. For members buckling in For members buckling in the plane perpendicular to the plane perpendicular to truss, ‘1’ shall be taken as truss, ‘l’ shall be taken as distance between centres of distance between points of intersection. restraint. 4.4 Maximum Table 3,Clause:3.8(Pg.20) Clause:3.7(Pg.30) Slenderness Compression member=180 Compression member=180 No change. Ratio (subjected to DL and IL) (subjected to DL and IL) Compression member=250 Compression member=250 (subjected to WL and EL) (subjected to WL and EL) 4.5 Built up Clause:7.6(Pg.48-50) Clause:5.7.2(Pg.47) Members Lacing of compression Lacing of compression No change with Lacing member shall be designed member shall be designed in the load for a transverse shear equal for a transverse shear calculations to at least 2.5 % of the axial equal to at least 2.5 % of and basic force in the member. the axial force in the design member. requirements. Slenderness ratio of the Slenderness ratio of the lacing bars shall not lacing bars shall not exceed 145. exceed 145. Angle of inclination with Angle of inclination with the axis of 400 to 700 to the the axis of member 400 to axis of built up section 700.(for both single & member(for both single& double lacing) double lacing). Max. spacing of lacing Max. spacing of lacing shall shall be such that min. be such that min. slenderness ratio (l/r) of slenderness ratio (l/r)of the the components of the components of the member member between between consecutive consecutive connection is connection is not greater not greater than 50 or 0.7 than 50 or 0.7 times the times the most most unfavourable (l/r) of unfavourable (l/r) of the the member as a whole, member as a whole, whichever is less. whichever is less. 44 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, July-August (2013), © IAEME 4.6 Built up Clause:7.7(Pg.50-52) Clause:5.8(Pg.51) Members Battens shall be designed to Battens shall be designed No changes with Battens carry the bending moment to carry the bending have been /Tie plates &shears arising from moment & shears arising made in the transverse shear force ‘V’ of from transverse shear force load 2.5 % of the total axial force ‘V’ of 2.5 % of the total calculation on the whole comp. axial force on the whole and basic member, at any point in the comp. member, at any design length of the member, point in the length of the requirements. divided equally between member, divided equally parallel planes of battens. between parallel planes of Spacing of battens centre to battens centre of end fastenings Spacing of battens centre shall be such that the to centre of end fastenings slenderness ratio (l/r)of the shall be such that the lesser main component over slenderness ratio(l/r) of the that distance shall be not lesser main component greater than 50 or greater over that distance shall be than 0.7 time the not greater than 50 or slenderness ratio of the greater than 0.7 time the member as a whole, about slenderness ratio of the its x-xaxis. (axis parallel to member as a whole, about the battens) its x-x axis. (axis parallel to the battens) 4.7 Column Base Clause:7.4(Pg.47) Clause:5.4(Pg.44) The concept Plate Minimum thickness of slab Minimum thickness of of effective base under axial slab base shall be area for load compression shall be t = 3.0w(a 2 − 0.25b2 ) σ bs transfer has t s = 2.5w( a 2 − 0.3b 2 )γ m 0 f y > t f been Where, introduced. Where, w =pressure or loading on w =uniform pressure from the underside of the below on the slab base base(MPa) under a , b = larger and smaller the factored load axial projection, respectively of compression(MPa) the slab base beyond the a , b = larger and smaller rectangle circumscribing projection, respectively of the column(mm) the slab base beyond the t = slab thickness (mm) rectangle circumscribing the σ bs =permissible bending column(mm) t f = flange thickness of stress in slab base(for all steels assumed as compression member (mm) 185MPa) f y = yield strength of steel. γ m 0 = partial safety factor against yield stress and buckling. 45 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, July-August (2013), © IAEME 5.0 Members subjected to bending 5.1 Bending Clause:8(Pg.52-59) Clause:6.2(Pg.55) --- Stress Laterally Supported Max. permissible stress, Beams: Design strength in σ bt orσ bc = 0.66fy (For bending shall be calculated strong &weak axis as per the formulas given on bending) the basis whether the section is susceptible to shear Max. permissible stress buckling before yielding. σ bt orσ bc forI-beams& Laterally Unsupported Beams: Design strength in Channels (based on bending shall be calculated section properties andl/ry ) as per the formulas given shall be referred from and resistance to lateral Table-6.1A to 6.1F(Pg.- torsional buckling should 57-62) as appropriate. not be checked for For beams & plate girders, a) bending is about minor max. permissible σ bc shall axis be computed as per b) Section is hollow or a equation given in Cl. solid bar 6.2.3(Pg.56) or Table- c) In case of major axis 6.2(Pg.64) may be referred bending, the non for σ bc calculated from dimensional fcbfor different values of slenderness ratio is fy.(All stresses in MPa) less than 0.4. 5.2 Bearing Clause:8.7.4(Pg.67) Clause:6.3(Pg.68) The partial Stress Should be less than the yield Max. permissible bearing safety factors stress of the steel divided by stress on net area of are based on Partial safety factor i.efy/1.1 contact, σ p = 0.75 ƒy the values given in Euro code. 5.3 Shear Clause:8.4(Pg.59-60) Clause:6.4(Pg.68) --- stresses Nominal plastic shear Max. permissible Shear resistance under pure shear stress, τ vm = 0.45 ƒy should be calculated using the formulas Vn = V p , and Average shear stress in Av f yw member calculated on the Vp = based on the cross section of the web 3 shall not exceed the limits shear are as specified for as mentioned in Cl. various sections. No.6.4.2 (Pg.69). Also Resistance to shear buckling refer Table-6.6A, B, C can be verified based on the (Pg.73-75) for stiffened value of ratio of depth to webs. web thickness. Two methods have been specified for calculation of nominal shear strength. They are 46 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, July-August (2013), © IAEME * Simple Post Critical Method (can be used for beams with or without intermediate transverse Stiffeners *Tension Field Method (can be used for beams with intermediate transverse stiffeners) 5.4 Effective Clause:8.6.1.2(Pg.64) Clause:6.6(Pg76)&Clause: --- length of No specific criteria are 3.7(Pg.30) compression mentioned. To calculate permissible flanges & But in order to avoid bending stress as max. buckling of the compression explained above in 5.1, slenderness flange in to the web, the appropriate effective ratio web thickness shall satisfy length shall be considered the criteria’s specified. referring this clause. *Max. Slenderness ratio for Compression flange of beam =300 Cl.3.7, Pg.3.1 *For Cantilever beams of projecting length ‘L’, referCl. No. 6.6.3, Pg.77. 6.0 Combined stresses 6.1 Axial Clause:9.3.1&9.3.2.2 Clause:7.1.1(Pg.90) Separate Compression (Pg70-71) governing & Bending Members subjected to σac,cal σ equations +[( C .σ ) σ 1− ac,cal ] combined axial compression σac mx bcx,cal bcx 0.6 fccx are specified and biaxial bending should σac,cal for different satisfy the relationship: +[( Cmy .σbcy,cal ) σbcy 1− ] types of 0.6 fccy sections. ( P P ) + K (C dy y my My Mdy ) + KLT ( Mz Mdz ) ≤1.0 ≤ 1.0 ( P P ) +0.6Ky (CmyMy Mdy ) +Kz ( Cmz Mz Mdz ) ≤1.0 σ If ac,cal 〈 0.15 , the dz Where, σ ac C my , Cmz =equivalent following equation shall uniform moment factor as be satisfied in lieu of the per Table 18 above. P =applied axial compression under factored σ ac,cal σ bcx ,cal σ bcy ,cal + + ≤ 1.0 load. σ ac σ bcx σ bcy M y , M z =maximum σ ac ,cal = calculated average factored applied bending axial compressive stress. moments about y and z axis σ bc ,cal = calculated bending of the member. compressive stress in Pdy , Pdz =design strength extreme fibre. under axial compression σ ac = permissible axial 47 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, July-August (2013), © IAEME governed by buckling about compressive stress in minor( y ) and major ( z ) member subject to axial axis compressive load. M dy , M dz =design bending σ bc = permissible bending strength about y (minor) or compressive stress in extreme fibre. z (major) axis considering laterally unsupported length f cc = elastic critical stress of the cross section. π 2E in compression = K y = 1 + ( λ y − 0.2 ) n y ≤ 1 + 0.8n y λ2 K z = 1 + ( λz − 0.2 ) nz ≤ 1 + 0.8nz x, y =represent x-x and y-y Where, planes. n y , nz =ratio of the actual Cm = 0.85 when side sway applied axial force to the prevented. design axial strength for Cm = 0.6 − 0.4 β ≥ 0.4 buckling about y and z when side sway is axis. prevented and not CmLT =equivalent uniform subjected to transverse loading between their moment factor for lateral supports in the plane of torsional buckling as per bending. Table 18 corresponding to the actual moment gradient between lateral supports against torsional deformation in the critical region under consideration. 6.2 Axial Clause:9.3.1 & Clause:7.1.2(Pg.90) Separate Tension 9.3.2.1(Pg.70-71) Member should satisfy the governing & Bending The reduced effective following condition. equations moment, M eff , under σat,cal σbtx,cal σbty,cal are specified + + 0.6 f 0.66 f 0.66 f ≤1.0 for different tension and bending should y y y not exceed the bending types of strength due to lateral sections. Where, torsional buckling, M d . σ at ,cal =calculated average M eff = [ M − (ψ TZ ec A )] ≤ M d axial tensile stress Where, σ bt ,cal =calculated bending M , T = factored applied tensile stress in extreme moment and tension fibre A=area of cross section x, y =represent x-x and y-y Z ec = elastic section planes modulus of the section w.r.t. extreme compression fibre ψ =0.8, if T and M can vary independently or otherwise=1.0 48 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, July-August (2013), © IAEME 6.3 Bending & Clause:9(Pg.69-70) Clause:7.1.4(Pg.91) The moment Shear Moment carrying capacity Equivalent stress reduction is of the section shall be calculated by the equation dictated by reduced by the amount as given in this clause shall the specified in the code (for not exceed the value, percentage high shear force). σ e = 0.9 f y . of shear No reduction is required for force w.r.t. Shear force value < 60% of allowable allowable shear capacity of shear force the section. in the section. 6.4 Bearing, No specific criteria are Clause:7.1.5(Pg.92) --- Bending & mentioned. Equivalent stress Shear calculated using the equation 2 2 τ2 , σe,cal = σbt,cal +σp,cal +σbt,calσp,cal +3 vmcal (OR) 2 2 σe,cal = σ bc,cal τ2 , +σp,cal +σbc,calσp,cal +3 vmcal shall not exceed the value, σ e = 0.9 f y . 7.0 Connections 7.1 Bolted 7.1.1 Permissible Clause:10(Pg.73-77) Clause:8.9.4(Pg.95), --- Stresses for No specific value is Table 8.1 bolts prescribed. Procedure given a) Axial tension 120 MPa for calculation of b) Shear 80 MPa permissible loads (Axial c ) Bearing 250 MPa Tension, Shear &Bearing). 7.1.2 Combined Clause:10.4.6(Pg.77) Clause:8.9.4.5(Pg.96) --- shear and No specific value is Individual stresses should tension in provided. Procedure given not exceed allowable bolts for calculation of values and combined permissible loads. stress ratio should not exceed 1.40. 7.1.3 Minimum Clause:10.2.2(Pg.73) Clause:8.10.1(Pg.96) No change pitch Shall not be less than 2.5 Shall not be less than 2.5 has been times the nominal diameter times the nominal made. of the fastener (Bolt/Rivet) diameter of the bolt. 7.1.4 Minimum Clause:10.2.4.2(Pg.74) Clause:8.10.2(Pg.97) Not much edge distance Should be >1.7 times hole Table 8.2 variation is dia. for sheared or hand- Distance from the centre observed in flame cut edges, &>1.5 of any hole to the edge of the end times hole dia. for rolled, a plate shall not be less results. machine-flame cut, sawn than that specified in Table and planed edges, from 8.2. the centre of the hole. When two or more parts are connected together, a line of bolts shall be provided at a distance of 49 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, July-August (2013), © IAEME not more than 37 mm+4t from the nearest edge, where t is the thickness of thinner outside plate in mm. In case of work not exposed to weather, this may be increased to 12t. 7.1.5 Maximum Clause:10.2.3(Pg.74) Clause:8.10.1(Pg.96) No change pitch Shall not exceed 32t or Shall not exceed 32t or has been 300mm whichever is less, 300mm whichever is less, made. where t is the thickness of where t is the thickness of the thinner outside plate. the thinner outside plate. 7.1.6 Maximum Clause:10.2.4.3(Pg.74) No specific criteria are --- edge distance Shall not exceed 12tε , mentioned. where t is the thickness of the thinne router plate, and ε = (250/fy)1/2 7.1.7 Clearance for Clause:10.2.1(Pg.73) Clause:3.6.1.1(Pg.28) More fastener As given in Table 19 1.5 mm in excess of the practical Holes nominal diameter of the aspect for bolt irrespective of the clearance diameter of the bolt, unless has been otherwise specified. considered. 7.2 Welded 7.2.1 Fillet welds 7.2.1.1 Permissible Clause:10.5(Pg.78) Clause:8.9.4.7, IS:800- --- stresses Shear stress shall not exceed 1984Clause:7.1.2 IS:816- 110MPa nor as calculated 1969(Pg.17) using clause 10.5.7(Pg.79- Shear stress shall not 81) exceed 110 MPa. 7.2.1.2 Effective Clause:10.5.3(Pg.78) Clause:8.9.4.7, IS:800- No Changes throat Shall not be < 3mm and not 1984Clause:6.2.3, have been thickness > 0.7t, where t is the IS:816(Pg.10) suggested thickness of the thinner Shall not be < 3 mm and plate. For stresses not > 0.7t, where t is the calculation in fillet welds thickness of the thinner joining faces inclined to plate. For stresses each other, effective throat calculation, the effective thickness shall be taken as throat thickness shall be K times the fillet size, where taken as K times the K is a constant. filletsize, where K is a constant. 7.2.1.3 Effective Clause:10.5.4(Pg.78) Clause:8.9.4.7, IS:800- --- length Shall be the overall length 1984,Clause:6.2.4,IS:816( of weld excluding end Pg.11) returns in case of Fillet Shall be the overall length welds and shall be the of the weld plus twice the 50 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, July-August (2013), © IAEME overall length of weld weld size. including end returns for Butt welds. 7.2.1.4 Effective Clause:6.2.3(Pg.10) Clause:8.9.4.7, IS:800- --- area Effective length times 1984, Clause:6.2.3, of weld Effective throat thickness IS:816(Pg.10) Effective length times effective throat thickness 7.2.1.5 Minimum Clause:10.5.4(Pg.78) Clause:8.9.4.7, IS:800- No Changes length of 1984Clause:6.2.4.1,IS:816 have been weld Shall not be less than four (Pg11) suggested. times the size of the weld. Shall not be less than four times the size of the weld. 7.2.1.6 Minimum Clause:10.5.2(Pg.78) Clause:8.9.4.7, IS:800- No Changes size of the 1984, have been weld Clause:6.2.2,IS:816(Pg.10) suggested Shall not be less than 3 mm. Shall not be less than 3 mm nor more than the thickness of the thinner The minimum size of the part joined. first run or the single run The minimum size of the weld shall be as given in first run or the single run Table 21(Pg 78). weld shall be as given in Table 1 in IS:816 to avoid risk of cracking in the absence of preheating. 7.2.2 Butt Welds 7.2.2.1 Permissible Clause:10.5.7(Pg.79) Clause:8.9.4.7, IS:800- --- stresses. Stresses in weld shall not 1984, Clause:7.1.1, exceed those permitted in IS:816(Pg.16) the parent metal. Stresses in weld shall not exceed those permitted in the parent metal. 7.2.2.2 Minimum Clause:10.5.2.4(Pg.78) Clause:8.9.4.7, IS:800- size of weld Size of butt weld shall be 1984, Clause:6.1.3, specified by the effective IS:816(Pg.5) throat thickness. Size of butt weld shall be specified by the effective throat thickness. 7.2.2.2 Effective Clause:10.5.4(Pg.78-79) Clause:8.9.4.7, IS:800- --- area of weld Effective length times the 1984, effective throat thickness Clause:6.1.6,IS:816(Pg.7) Effective length times the effective throat thickness 7.2.2.3 Effective Clause:10.5.3.3,(Pg.78) Clause:8.9.4.7, IS:800- throat 1984 thickness For complete penetration, Clause:6.1.4,IS:816(Pg.6) effective throat thickness For complete penetration, 51 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, July-August (2013), © IAEME shall be taken as thickness effective throat thickness of thinner part joined. shall be taken as the thickness of thinner part For an incomplete joined. penetration, effective throat For incomplete thickness shall be taken as penetration, effective the minimum thickness of throat thickness shall be the weld metal common to taken as the thickness of the parts joined, excluding the weld metal common to reinforcement. the parts joined, excluding reinforcement. 8.0 Gantry Girder 8.1 Increase in No specific criteria are Clause:3.9.3(Pg.31) Stresses are stresses given. While considering to be simultaneous effects of calculated vertical & horizontal surge using loads of cranes for the adequate combination given in Cl. Partial Safety 3.4.2.3 & 3.4.2.4, the factors. permissible stresses may be increased by10 %. 8.2 Limiting Clause:5.6.1(Pg.31) Clause:3.13.1.3(Pg.35) --- deflection Table 6 should be referred. Vertical deflection: Under DL and IL shall not exceed the following: i. L/500, where manually operated cranes are operated and for similar loads ii. L/750, where electric overhead travelling cranes operated up to 50 tonnes iii. L/1000, where electric overhead travelling cranes operated over 50 tonnes iv. L/600, other moving loads such as charging cars etc. L=span of the crane runway girder. Horizontal deflection: At the caps of columns in single storey buildings, the horizontal deflection due to lateral forces should not exceed l / 325 of the actual length ‘ l ’ of the column. 52 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, July-August (2013), © IAEME 9.0 Design and Detailing for Earthquake Loads 9.1 Load Clause:12.2 (Pg.87) No such criteria are given. --- Combination Two more combinations have to be considered 1) 1.2 DL + 0.5 LL ± 2.5 EL 2) 0.9 DL ± 2.5 EL 9.2 Lateral Load The Building has been No such classification has --- Resisting classified as been made System 1) Braced Frame System a) Ordinary concentrically Braced Frames (OCBF) b) Special Concentrically Braced Frame(SCBF) c) Eccentrically Braced Frame (EBF) 2) Moment Frame System a) Ordinary Moment Frame (OMF) b) Special Moment 3) Frame (SMF) Various criteria for loads on members are specified for different lateral load resisting systems. 10.0 Fatigue 10.1 Reference Clause:13.2.1(Pg.91) No such criteria are --- design Conditions when fatigue mentioned. Condition design becomes necessary are mentioned along with a plot of standard S-N curve for each category. A capacity reduction factor µr is to be applied when plates greater than 25 mm tk. Are joined by transverse fillet orbutt welding. 10.2 Partial Safety Clause:13.2.3(Pg.92) No such criteria are --- Factors Based on consequences of Mentioned. fatigue failure, component details have been classified and Partial Safety Factors are given for each type.(Refer Table 25, Pg. 92) 10.3 Detail Clause:13.3(Pg.92-98) No such criteria are --- Category Tables 26 (a) to (d) indicate mentioned. the classification of 53 International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 4, July-August (2013), © IAEME different details into various categories for the purpose of assessing fatigue strength. 11.0 Fire Resistance 11.1 Clause:13( Pg.105-110) No such criteria are --- Following points have been mentioned. discussed and relevant design standards have been mentioned Fire Resistance Level Period of Structural adequacy *Variation of mechanical properties of Steel with Temperature *Limiting Steel Temperature *Thermal Increase with Time in Protected members *Temperature increase with Time in unprotected Members *Determination of period of Structural adequacy from a single test *Three-Sided Fire exposure condition. CONCLUSION An explicit comparison of important clauses of IS:800-2007 and IS:800-1984 presented in this paper gives a quick insight to the readers about the changes made in corresponding clauses of the old and latest codes of practice. REFERENCES 1. IS 800:2007, Indian Standard Code of Practice for General Construction in Steel, Bureau of Indian Standards, New Delhi. 2. IS 800:1984, Indian Standard Code of Practice for General Construction in Steel, Bureau of Indian Standards, New Delhi. 3. Dr.Subramanian.N, (2008), “Code of Practice on Steel Structures - A Review of IS 800: 2007”, Civil Engineering & Construction Review. 4. Dr.Subramanian.N, (2009),“Design of Steel Structures”, Oxford University Press, New Delhi. 5. Vidula S. Sohoni and Dr.M.R.Shiyekar, “Concrete–Steel Composite Beams of a Framed Structure for Enhancement in Earthquake Resistance”, International Journal of Civil Engineering & Technology (IJCIET), Volume 3, Issue 1, 2012, pp. 99 - 110, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316. 54

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