RCC 2 Way Slab Design (IS-456-2000)
Prepared by :- #abilas
2 way slab Design should be preferred
| Inputs | Outputs |
|---|---|
| Material characteristics, Slab Dimensions, Loads Applied | Design Material Requirement |
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GEC |
Ghumadwar Engineering Consultancy |
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Project Name:- |
RCC Framed Structure Building |
Proj. no.- |
220001 |
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Structure Details:- |
Two Way RCC Slab (In Framed Structure) Design |
Cal. By:- |
ASG |
Date:- |
4/7/2022 |
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Design Note no.:- |
Owner-Client-Structure_abbrevation-Dgn_note_no.1 |
Chk. By:- |
RPP |
Rev no.:- |
R0 |
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Slab Design (S1) |
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1 |
Input Data |
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Long Span (Ly) |
= |
m |
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Short Span (Lx) |
= |
m |
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Panel size |
= |
6
|
x |
4.32
|
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Concrete Grade (fck) |
= |
Mpa |
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Steel Grade (fy) |
= |
Mpa |
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Clear Cover (Cc) |
= |
mm |
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Ly/Lx |
= |
1.39
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Two-way
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Edge Condition. |
5
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(Refer P.No.-91, Table 26, IS:456-2000) |
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2 |
Load calculations |
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Assume D |
= |
mm |
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Assume Eff. Cover (Ceff) |
= |
30
|
mm |
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Dead load of slab |
= |
D x 25 |
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|
= |
3.75
|
kN/m2 |
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Floor finish + Superimposed Dead Loads |
= |
kN/m2 |
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Live load |
= |
kN/m2 |
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Total load (W) |
= |
7.75
|
kN/m2 |
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Ast min = |
0.0012 x D x 1000 |
= |
180
|
mm2/m |
(As per clause 26.5.2.1, IS 456-2000) |
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3 |
Force/ Moments calculations |
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αx (+ve) |
= |
0.043
|
(Refer P.No.-91, Table 26, IS:456-2000) |
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αx (-ve) |
= |
0.056
|
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αx (+ve) |
= |
0.035
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αx (-ve) |
0.000
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Moment |
Ast calc. |
Ast reqd. |
8 mm @ |
10 mm @ |
12 mm @ |
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(kNm) |
(mm2/m) |
(mm2/m) |
c/c in mm |
c/c in mm |
c/c in mm |
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9.293
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182.750
|
182.750
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273.160
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300.000
|
300
|
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12.251
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243.005
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243.005
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205.428
|
300.000
|
300.000
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7.593264
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148.605
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180.000
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277.333
|
300
|
300
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0
|
0.000
|
180.000
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277.333
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300.000
|
300
|
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Maximum C/C spacing between Primary Bars is 300, 3d mm |
(As per clause 26.3.3.b1 , IS 456-2000) |
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Maximum C/C spacing between Secondary Bars is 450, 5d mm |
(As per clause 26.3.3.b2 , IS 456-2000) |
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4 |
Design of Slab |
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d required |
= |
\[\sqrt{(M_u 10^6)/(0.133 f_{ck} b)} =\] |
55.410
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mm |
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D provided |
= |
mm |
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dx provided |
= |
120
|
mm |
(for shorter span reinforcement) |
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dy provided |
= |
110
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mm |
(for longer span reinforcement) |
Safe
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Dia of bar(mm) |
Spacing (mm) |
Ast prov. in mm2/m |
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Provide 150 mm Thick Slab
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Ast for shorter span @ midspan(+Mx) = |
mm dia bar @ c/c |
520
|
Safe
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Ast for shorter span @ support (-Mx) = |
mm dia bar @ c/c |
520
|
Safe
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Ast for longer span @ midspan (+My) = |
mm dia bar @ c/c |
520
|
Safe
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Ast for longer span @ support (-My) = |
mm dia bar @ c/c |
520
|
Safe
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Maximum C/C spacing between Primary Bars = 150 mm
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OK
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(As per clause 26.3.3.b1 , IS 456-2000) |
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Maximum Dia of Bars is D/8 = 18.75 mm
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OK
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(As per clause 26.5.2.2 , IS 456-2000) |
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5 |
Check for Deflection : |
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Percentage of Tension renforcement |
= |
0.433333333
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% |
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fs = |
0.58 fy Area of c/s of steel required |
= |
101.918
|
MPa (Refer P.No.-38, IS-456-2000) |
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Area of c/s of steel provided |
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Span/ eff. Depth ratio (Lx/d) |
= |
(As per clause 23.2.1, IS-456-2000) |
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Modification factor = |
1 |
= |
3.07
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0.225 + 0.00322 fs - 0.625 log10(bd/(100Ast)) |
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Allowable Span/eff. Depth ratio |
= |
70.61
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Effective Depth (dx) required |
= |
61.181
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mm |
Safe
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Overall Depth (D) required |
= |
91.181
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mm |
Safe
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6 |
Check for Shear : |
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a |
At Short direction |
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Vu (Short dir.) = 1.33 (1.5 W Lx/4) |
= |
16.74
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kN |
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Ï„v = Vu / bd = |
0.140
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MPa |
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pt. % |
= |
0.433333333
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β |
= |
8.038
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Refer P.No.-175, SP 16, β = max(0.8 fck / (6.89 pt.), 1) |
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Ï„c (Table 19) |
= |
0.468
|
MPa |
Refer P.No.-175, SP 16, τc =[0.85 sqrt(0.8 fck)(sqrt(1+ 5β)-1)] / 6β |
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k |
= |
1.3
|
(As per clause 40.2.1.1, IS 456-2000) |
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k Ï„c |
= |
0.608
|
Safe
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b |
At Long direction |
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Vu (Long dir.) = 1.33 (1.5 W (Lx Ly/2-Lx Lx/4))/Ly |
= |
21.427
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kN |
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Ï„v = Vu / bd = |
0.195
|
MPa |
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pt. % |
= |
0.473
|
% |
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β |
= |
7.369
|
Refer P.No.-175, SP 16, β = max(0.8 fck / (6.89 pt.), 1) |
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Ï„c (Table 19) |
= |
0.485
|
MPa |
Refer P.No.-175, SP 16, τc =[0.85 sqrt(0.8 fck)(sqrt(1+ 5β)-1)] / 6β |
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k |
= |
1.3
|
(As per clause 40.2.1.1 , IS 456-2000) |
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k Ï„c |
= |
0.631
|
MPa |
Safe
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Moments Considered |
Short Span Coefficients αx |
Long Span |
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Coeff αy |
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Values of ly/lx |
ly/lx |
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1.0 |
1.1 |
1.2 |
1.3 |
1.4 |
1.5 |
1.75 |
2.0 |
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Values of ly/lx |
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Two Short Edges Discontinuous
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5A
|
Negative Moment-5
|
0.045
|
0.049
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0.052
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0.056
|
0.059
|
0.060
|
0.065
|
0.069
|
0.000
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5B
|
Positive Moment-5
|
0.035
|
0.037
|
0.040
|
0.043
|
0.044
|
0.045
|
0.049
|
0.052
|
0.035
|
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k |
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D |
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