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Design+of+Slab(Two+Way)

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TWO WAY SLAB DESIGN SHEET
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  SLAB DESIGN :-Out House Room (One long & one short edge discontineous)(TWO WAY) in ft.Short Span (Clear)11.003.35mLong Span (Clear)17.55.33mLive Load on the Slab (LL)3.50KN / sqmComp.stess of concrete M - 15 (fck)15.00N / sqmTensile stress of steel (fy)415.00N / sqmUnit wt of concrete25.00KN / cumUnit wt of floor finish 50 mm24.00KN / sqmClear concrete cover 15.00mmBearing of slab230.00mmOverall depth 111.76mmProvide Overall depthD 125.00 mmDia of bars for short direction10.00mmDia of bars for long direction10.00mmEffective Depthd105.00mm Loading on the slab Dead Load of the slab (DL)3.13KN / sqmFloor Finish1.20KN / sqmOther Load0.50KN / sqmLive Load on the slab3.50KN / sqmTotal Load on the slab (TL)8.33KN / sqmDesign Load = (Total Load x Load Factor i.e. 1.5)12.49KN / sqmEffective Spanlx3.46mly5.44mRatioly/lx 1.573From Table (26 or 27 of IS 456) BM Coefficients are as follows; 1.5  a x1.75  a yFor negative moments (at top)0.0750.077626760.0840.047For positive moments (at bottom)0.0560.058043030.0630.035 Calculated BM per unit width of slab are as follows; Mx = a x w lx 2 My = a y w lx 2 For negative moments (at top)11.597.02KN-m/mFor positive moments (at bottom)8.675.23KN-m/mEffective depth of slab will now be fixed up on consideration of of flexural strength as well as control of deflection. Flexural strength consideration Maximum BM =11.59KN-m/mBM =0.36 x fck x 0.48 (1-0.42 x 0.48) x 1000 d 2 =BM x 10 6 N-mm/mor 0.36 x 15 x 0.48 (1-0.42 x 0.48) x 1000 d 2 =11590086.67ord =75mmTension R/F for the positive BM along the short span isBM =8.67 Ast =BM / 0.87 x fy (1-0.42 x 0.48) x d=8666133/ 0.87 x 415 (1-0.42 x 0.48) x 75=401.7mm2/m Control of deflection  Actual Span / effective depth ratio=3458/75= 46.20 pt = 100 Ast/bd = 100 x 401.7 / 1000 x 75 = 0.54 From Modification curve, Modification factor =1.2Basic value of span / effective depth ratio =26Therefore permitted value of span / effective depth ratio =26 x 1.2  = 31.2  Actual S/d is >Permitted S/dHence effective depth d should be increase Try an effective depth d = 100 mmTension R/F for short span +BM is given by =0.87 x fy x Ast (d - fy x Ast / (fck x 1000))=8.67 x 1000000 0.87 x 415 x Ast (100 - 415 x Ast / (15 x 1000))=8666132.809 8666271 8666133   Ast =258.52 Actual Span / effective depth ratio=3458/100= 34.58 pt = 100 Ast/bd = 100 x 258.52 / 1000 x 100 = 0.259From Modification curve, Modification factor =1.45Basic value of span / effective depth ratio =26Therefore permitted value of span / effective depth ratio =26 x 1.45= 37.70  Actual S/d is <Permitted S/dHence effective depth d should be OK  Adopt Overall thickness (D) = 120 mmMinimum R/F in slab =0.12% of area of slab=0.12 x D x 1000 / 100 = 144 mm2/m8 mm dia 349 mm c/c 0.87 x 415 x Ast (d - 415 x Ast / (15 x 1000))=BM x 1000000 Effective depth for R/F in long direction will, therefore, be = 100 - dia. Of long R/F=100 - 10=90.00mmTension R/F per unit width of slab calculated by above eq. For different BM are as follow; Bendind Moments Short SpanLong SpanFor negative moments (at top)11.59KN-m/m7.02KN-m/mFor positive moments (at bottom)8.67KN-m/mIncrease SteelKN-m/m Reinforcements Short SpanLong SpanTop R/F (At support)357.00233.00mm2/mBottom R/F (At Mid Span)258.52160.00mm2/mThese R/F will be provided within the middle strips in the two directions. Adopting 8 or 10 mm dia bars for the R/F, the calculated spacing of bars will be as follows; Reinforcements Spacing Dia of barsShort SpanDia of barsLong SpanTop R/F (At support)10.0021010.00330mm c/cBottom R/F (At Mid Sp10.0030010.00490mm c/cMaximum Spacing300270mm c/c No. of bars in slab Short SpanLong SpanTop R/F26.00Nos. of Length 5439 mm11.00Nos. of Length 3457.8 mmBottom R/F19.00Nos. of Length 5439 mm8.00Nos. of Length 3457.8 mm OK  SLAB DESIGN :-Out House Room Edges conditions :-(One long & one short edge discontineous) Room Size :- 11 x 17.5 Ft. Thickness of Slab :- 120 mm Concrete Grade M-15 (fck 15 N/Sqm)Steel :- HYSD (fy 415 N/Sqm)Live Load :- 3.5 KN/SqmFloor Finish + Other Load :- 1.2 + 0.5 KN/SqmMxMyFor negative moments (at top) Support :-11.597.02KN-m/mFor positive moments (at bottom) Mid Span:-8.675.23KN-m/mMaximum R/F(Flexural Consideration) :-401.72 mm2/m, 8 mm dia. 125 C/C Short Span Top At support :-357.00mm2/m10 mm dia. 210 mm c/cBottom At Mid Span :258.52mm2/m10 mm dia. 300 mm c/c Long Span Top At support :-233.00mm2/m10 mm dia. 270 mm c/cBottom At Mid Span :160.00mm2/m10 mm dia. 270 mm c/cMinimum R/F :-144.00mm2/m8 mm dia 349 mm c/c Maximum Spacing :-270mm Calculated BM per unit width of slab are as follows;Required Reinforcements & Spacing 246323972.xls.ms_office[Report]3/810/3/2014(9:46 AM)  SLAB DESIGN :-Frontside Bed Room Edges conditions :-(All four edges contineous) Room Size :- 12.5 x 13.25 Ft. Thickness of Slab :- 125 mm Concrete Grade M-15 (fck 15 N/Sqm)Steel :- HYSD (fy 415 N/Sqm)Live Load :- 3.5 KN/SqmFloor Finish + Other Load :- 1.2 + 0.5 KN/SqmMxMyFor negative moments (at top) Support :-6.696.13KN-m/mFor positive moments (at bottom) Mid Span:-5.044.60KN-m/mMaximum R/F(Flexural Consideration) :-307.77 mm2/m, 8 mm dia. 162 C/C Short Span Top At support :-183.52mm2/m8 mm dia. 270 mm c/cBottom At Mid Span :136.65mm2/m8 mm dia. 300 mm c/c Long Span Top At support :-182.61mm2/m8 mm dia. 270 mm c/cBottom At Mid Span :135.04mm2/m8 mm dia. 294 mm c/cMinimum R/F :-150.00mm2/m8 mm dia 335 mm c/c Maximum Spacing :-294mm Calculated BM per unit width of slab are as follows;Required Reinforcements & Spacing   UP 8 mm dia. 6 c/c 8 mm dia. 7 c/c 8 mm dia. 9 c/c 246323972.xls.ms_office[1]4/810/3/2014[9:46 AM]
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