ACI 318 Code Comparison with IS456-2000

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Code Comparison between IS456-2000 and ACI 318
Presented by K.Gokulprabhu N.Kumaresan
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General basic comparison
DESCRIPTION IS 456 2000 IS 456 2000 ACI 318 - 2002 ACI 318 - 2002
DESCRIPTION CLAUSE Contents CLAUSE Contents
Loading combination 36.4.1 a) 1.5 DL 1.5 LL b) 1.5 DL l1.5 WL c) 1.2 DL1.2 LL1.2wl   9.2.1     U 1.4(DF) U 1.2(DFT) 1.6(LH0.5(Lr or S or R) U 1.2D1.6(Lr or S or R)(L or 0.8W) U1.2D1.6WL0.5(Lr or S or R) U 1.2DEL0.2S U 0.9D1.6W1.6H U 0.9DE1.6H
Elastic modulus for concrete and steel 6.2.3.1 Ec5000 ?(fck) N/mm2 Es200xE3 N/mm2 8.5.1 Ec 57000?fc psi Es 29x106 psi
Mu limit Mu limit 0.138 Fck b d2 Mulimit
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DESCRIPTION IS 456 2000 IS 456 2000 ACI 318 - 2002 ACI 318 - 2002
DESCRIPTION CLAUSE Contents CLAUSE Contents
Span to depth ratio in slab 23.2.1 Cantilever - 7 Simply supported - 20 Continuous - 26 One-way slab- 20 Continuous slab-24
Min reinforcement in slab Plain bar-0.15 High strength bar-0.12 200/fy
Nominal cover Columns Not less than 40mm When dimension is 200mm or size of bar is 12mm then cover is 25mm Footings Not less than 50mm Slabs Not less than 15mm Beams not less than 20mm Refer P-47 Table 16A of IS code to get the cover details for fire resistance   Footing Resting on mat 2 Resting on earth 3 Top of piles 2 Beams and columns For dry conditions Stirrups, spirals, ties 1.5 Main reinforcement 2 Exposed to earth Stirrups, spirals, ties 2 Main reinforcement 2.5 Slabs No. 11bars 0.75 No. 14 18 bars 1.5
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DESCRIPTION IS 456 2000 IS 456 2000 ACI 318 - 2002 ACI 318 - 2002
DESCRIPTION CLAUSE Contents CLAUSE Contents
T beams 23.1.1 For T beams For L beams 8.10.3   Width of slab effective as T beam flange shall not exceed one quarter of the span length of the beam Effective overhang of flange on either of web shall not exceed - 8 slab thickness - ½ clear dist. Between the web For slab on one side - 1/12 of span of beam - 6 slab thickness - ½ clear dist. Between the web
Minimum area of tension reinforcement 26.5.1.1.a Ast(min) 0.85 b d / Fy 3.12.5.3 For flexural members Ast(min) 3?fc /fy bwd And not less than 200bwd / fy For slabs and foundation Astmin 0.14 Grade 40-50 steel 0.2 Grade 60 steel 0.18
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DESCRIPTION IS 456 2000 IS 456 2000 ACI 318 - 2002 ACI 318 - 2002
DESCRIPTION CLAUSE Contents CLAUSE Contents
Minimum horizontal distance between the bars 26.3.2 Greater of this following 1)larger diameter of the bars 2)Size of the aggregate 5mm Slabs Main bars 3d or 300mm Distribution bars 5d or 450mm not greater than the above Beams Refer to the IS code P-46 Table-15 it depends on the percentage redistribution 3.12.11.1 Flexural member   And not greater than
Side face reinforcement 26.5.1.3 When depth gt750mm Total area of reinforcement 0.1 area of the web and spacing not exceeding 300mm 10.6.7 When d gt36 Total longitudinal reinforcement not greater than half of the tensile reinforcement Spacing Ssk not greater than d/6, 12 na and 1000Ab / (d-30)

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DESCRIPTION IS 456 2000 IS 456 2000 ACI 318 - 2002 ACI 318 - 2002
DESCRIPTION CLAUSE Contents CLAUSE Contents
Maximum spacing of the tension bars 26.3.3 1) 0 re distribution of the moment 180mm 2) For other percentage of redistribution refer table 15
Compression steel / Tension steel 1) M gt Mu li mit compression steel is required Asc M - Mu li mit / (352 0.446 fck) (d - d) Ast (Pt(limit) Pt2) b d / 100 2) if M lt Mu li mit compression steel is not required Ast Pt b d / 100
Span / Effective depth check 23.2.1 (a) Basic span / Effective depth 26 Effective span / MF d ? 26 MF taken from fig 45 using Pt and fs Fs 0.58 fy (Astreq / Astpro) Or MF (tension) 1 / (0.2250.00322 fs 0.625) ? 2 MF (compression) 1.6 Pc / Pc 0.275 ? 1.5
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DESCRIPTION IS 456 2000 IS 456 2000 ACI 318 - 2002 ACI 318 - 2002
DESCRIPTION CLAUSE Contents CLAUSE Contents
Shear reinforcement Asv 0.46 Sv 0.87 fy If?V gt ?c   Asv (v - Cv) b d 0.87fy d   ?c-refer table 19 ? Cmax 2   ?V vU / bd ?c taken from table 19 using Pt and fck values ?V lt ?c shear reinforcement is not required (Asv / Sv)min (0.4 b / 0.87 fy) ?clt ?v lt ?c max / 2 (Asv / Sv) Vu -?cbd / 0.87fyd ?c can be derived from this formula ?c 0.76 (fck((15?)0.5 1))0.5 / 6? ? 0.8fck / 6.89Pt ? Vn ?Vu where Vu factored shear Vn nominal shear Vn Vc VS Vc 2?fc bwd For members shear and flexure and for detailed analysis use Vc (1.9?fc 2500?w Vu d / Mu ) bwd And not greater than 3.5?fc bwd Quantity Vu d / Mu not greater than 1 For members subj. to axial compression Vc 2 (1Nu / 2000Ag) ?fc bwd For detailed analysis Mm Mu Nu (4h d) / 8 Vc shall not be greater than Vc 3.5?fc bwd ?(1 Nu / 500Ag)  
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DESCRIPTION IS 456 2000 IS 456 2000 ACI 318 - 2002 ACI 318 - 2002
DESCRIPTION CLAUSE Contents CLAUSE Contents
Shear reinforcement For members subjected to axial tension Vc 2(1 Nu / 500Ag) ?fc bwd but not less than zero Where Nu is negative for tension   Nominal shear strength provided by concrete when diagonal cracking results results from the combined shear and moment Shear strength Vci 0.6?fc bwd Vd Vi Mcr / Mmax and not less than 1.7 ?fc bwd Mcr I / t (6?fc fpe fd)
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DESCRIPTION IS 456 2000 IS 456 2000 ACI 318 - 2002 ACI 318 - 2002
DESCRIPTION CLAUSE Contents CLAUSE Contents
Spacing of shear reinforcement 11.5.4.1     11.5.4.3 Not greater than d/2 When Vs exceeds 4?fc bwd the above spacing is reduced to 1/2
Minimum shear reinforcement 11.5.5.1 If Vu gt ½ ?Vc Av 0.75?fc bws / fy Not less than 500 bws / fy
Spacing of the shear reinforcement 11.5.6.2 Vu gt ? Vc Vs Vu - ? Vc / ? For straight bars Vs Avfyd / s Inclined stirrups Vs Avfy (sin? cos?)d / s Group of bars all bent up Vs Avfysin? not greater than 3 ?fc bwd   Spacing are calculation for straight bars Av / s Vu - ?Vc / ?fyd
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DESCRIPTION IS 456 2000 IS 456 2000 ACI 318 - 2002 ACI 318 - 2002
DESCRIPTION CLAUSE Contents CLAUSE Contents
Torsion 41.4.2 The longitudinal reinforcement shall be designed to resist an equivalent BM Me1 Mu Mt Mt Tu (1D/b / 1.7) If Mt gt Mu Then longitudinal reinforcement shall be provided on flexural compression member to withstand the moment Me2 11.6.1                                     11.6.3        Torsion can be neglected when For non prestressed members Tu lt f?fc(A2 cp / Pcp) For non prestressed members subjected to axial tensile or compressive force     If it exceeds the condition as per 11.6.1 Calculate the factored torsional moment For solid sections     For hollow sections
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DESCRIPTION IS 456 2000 IS 456 2000 ACI 318 - 2002 ACI 318 - 2002
DESCRIPTION CLAUSE Contents CLAUSE Contents
Transverse reinforcement 41.4.3 Total transverse reinforcement not less than  11.6.3.6
Longitudinal reinforcement 11.6.3.7 Additional longitudinal reinforcement shall be not less than
Minimum torsion reinforcement 11.6.5 When Tu gt values of 11.6.1 Not less than
Minimum total area of longitudinal torsional reinforcement 26.5.1.7 At least one longitudinal bar in each tie. When c/s exceeds 450mm additional reinforcement to be provided 11.6.5.2 At/ s shall not be less than
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DESCRIPTION IS 456 2000 IS 456 2000 ACI 318 - 2002 ACI 318 - 2002
DESCRIPTION CLAUSE Contents CLAUSE Contents
Spacing of the torsion reinforcement 26.5.1.3 Rectangular closed stirrups. Spacing shall not exceed x1, x1y1 / 4 , 300mm 11.6.6 Spacing shall not exceed  12 or PA/8
Column reinforcement 26.5.3.1                          39.4.1         0.8 to 6 of gross c/s area 4 rectangular bars 6- circular bars Minimum dia. 12mm Spacing of bars not greater than 300mm SPIRAL REINFORCEMENT Ratio of volume of helical reinforcement to volume of core shall not be less than 10.9 Minimum longitudinal reinforcement 0.01 to 0.08 gross cross sectional area Minimum bars 4 rectangular bars 3 triangular bars 6- enclosed spirals SPIRAL REINFORCEMENT   Minimum diameter 3/8 no.3 bar LATERAL TIES Diameter not less than 0.02 times greater dimension of the member No.3 to No. 5 bar Vertical spacing of bar Not greater than -16 times dia. Longitudinal bar - 48 times dia. Of tie bar
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DESCRIPTION IS 456 2000 IS 456 2000 ACI 318 - 2002 ACI 318 - 2002
DESCRIPTION CLAUSE Contents CLAUSE Contents
Column reinforcement 26.5.3.2 d Maximum pitch not greater than 75mm   LATERAL TIES Pitch of the transverse reinforcement shall not be more than the least of the following - least lateral dimension - 16 dia. Longitudinal bar - 300mm dia. Of the lateral ties not less than ¼ of the largest longitudinal bar Minimum diameter 3/8 no.3 bar LATERAL TIES Diameter not less than 0.02 times greater dimension of the member No.3 to No. 5 bar Vertical spacing of bar Not greater than -16 times dia. Longitudinal bar - 48 times dia. Of tie bar - 0.5 times least lateral dimension
Column reinforcement 10.3.6.1
Foundations Footing thickness 34.1.2   Thickness at the Edge Footing on soil not less than 150mm Piles 300mm 15.7 Depth of the footing above the bottom reiforcement should not be less than - Footing on soil 6 - footing on piles 12 
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DESCRIPTION IS 456 2000 IS 456 2000 ACI 318 - 2002 ACI 318 - 2002
DESCRIPTION CLAUSE Contents CLAUSE Contents
Footing - Critical section for shear 34.2.4.2 D / 2 distance alround the face of the column 15.5.4   dp / 2, alround the face of the column
Minimum reinforcement in footings 34.5.2 Nominal reinforcement for concrete thickness greater than 1m shall be 360mm2.this provision does not supercede the requirement of the min. tensile reinforcement based on depth calculation  Longitudinal reinforcement atleast 0.5 of the c/s area of the supported column Astmin 0.0018bh Grade 40-50 steel 0.2 Grade 60 steel 0.18
Development length of bars is taken from the table 26.2.1.1 12.2.1 For deformed bars Not greater than 2.5 Ld not less than 12
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Slender Columns with biaxial bending Isolated
footing with Moment Click