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Flat Slab Design to Bs8110

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Microsoft Word - FLAT SLAB DESIGN TO BS8110-PART 1-1997.docx

GEODOMISI Ltd. - Dr. Costas SachpazisCivil & Geotechnical Engineering Consulting Company for Structural Engineering, Soil Mechanics, Rock Mechanics, Foundation Engineering & Retaining Structures.Tel.: (+30) 210 5238127, 210 5711263 - Fax. : + 30 210 5711461 - Mobile: (+30) 6936425722 & (+44) 7585939944, castas@sachpazis.infaProject: Flat Slab Analysis & Design, In accordance with BS8110:PART 1:1997Job Ref.SectionCivil & Geotechnical EngineeringSheet no./rev. 1Calc. byDr. C. SachpazisDate18/01/2014Chk'd byDateApp'd byDateFLAT SLAB DESIGN TO BS8110:PART 1:1997Slab geometry

Spanx = 7200 mmSpany = 7200 mmlx = 400 mmly = 400 mmlx1 = 250 mmly1 = 250 mmex = lx1 / 2 = 125 mmey = ly 1 / 2 = 125 mmLx = Spanx - lx = 6800 mmLy = Spany - ly = 6800 mmLxi = Spanx - lx / 2 = 7000 mmLyi = Spany - ly / 2 = 7000 mmSpan of slab in x-direction;Span of slab in y-direction;Column dimension in x-direction;Column dimension in y-direction;External column dimension in x-direction; External column dimension in y-direction; Edge dimension in x-direction;Edge dimension in y-direction;Effective span of internal bay in x direction; Effective span of internal bay in y direction; Effective span of end bay in x direction; Effective span of end bay in y direction;Slab details

h = 250 mmDepth of slab;

SAGGING MOMENTSEnd bay A-BEffective span;Depth of reinforcement; Midspan moment; Support moment;Design reinforcementLever arm;Area of reinforcement designed; Minimum area of reinforcement required; Area of reinforcement required;Provide 20 dia bars @ 150 centresArea of reinforcement provided;Check deflectionDesign service stress;Modification factor;Allowable span to depth ratio;Actual span to depth ratio;GEODOMISI Ltd. - Dr. Costas SachpazisCivil & Geotechnical Engineering Consulting Company for Structural Engineering, Soil Mechanics, Rock Mechanics, Foundation Engineering & Retaining Structures.Tel.: (+30) 210 5238127, 210 5711263 - Fax. : + 30 210 5711461 - Mobile: (+30) 6936425722 & (+44) 7585939944, castas@sachpazis.infaProject: Flat Slab Analysis & Design, In accordance with BS8110:PART 1:1997Job Ref.SectionCivil & Geotechnical EngineeringSheet no./rev. 1Calc. byDr. C. SachpazisDate18/01/2014Chk'd byDateApp'd byDateCharacteristic strength of concrete; Characteristic strength of reinforcement; Characteristic strength of shear reinforcement; Material safety factor;Cover to bottom reinforcement;Cover to top reinforcement;Loading detailsCharacteristic dead load;Characteristic imposed load;Dead load factor;Imposed load factor;Total ultimate load;Moment redistribution ratio;Ratio of support moments to span moments;DESIGN SLAB IN THE X-DIRECTIONfcu = 35 N/mm2 fy = 500 N/mm2 fyv = 500 N/mm2 Ym = 1.15 c = 20 mm c' = 20 mmGk = 7.000 kN/m2 Qk = 5.000 kN/m2 Yg = 1.4 Yq = 1.6Nult = (Gk x yg) + (Qk x yq) = 17.800 kN/m2 Pb = 1.0 i = 1.0L = 7000 mmd = 200 mmm = (Nult x L2) / (2 x (1 + V(1 + i))2) = 74.823 kNm/m m' = i x m = 74.823 kNm/mK = 0.402 x (pb - 0.4) - 0.18 x (pb - 0.4)2 = 0.176 K = m / (d2 x fcu) = 0.053Compression reinforcement is not requiredz = min((0.5 + V(0.25 - (K / 0.9))), 0.95) x d = 187.3 mm As_des = m / (z x fy / Ym) = 919 mm2/m As_min = 0.0013 x h = 325 mm2/m As_req = max(As_des, As_min) = 919 mm2/mAs_prov = n x D2 / (4 x s) = 2094 mm2/mPASS - Span reinforcement is OKfs = 2 x fy x As_ req / (3 x As_ prov x Pb) = 146 N/mm2 ki = min(0.55+(477N/mm2-fs)/(120x(0.9N/mm2+(m/d2))),2) = 1.545 0.9 x 26 x ki = 36.151 L / d = 35.000

GEODOMISI Ltd. - Dr. Costas SachpazisCivil & Geotechnical Engineering Consulting Company for Structural Engineering, Soil Mechanics, Rock Mechanics, Foundation Engineering & Retaining Structures.Tel.: (+30) 210 5238127, 210 5711263 - Fax. : + 30 210 5711461 - Mobile: (+30) 6936425722 & (+44) 7585939944, castas@sachpazis.infaProject: Flat Slab Analysis & Design, In accordance with BS8110:PART 1:1997Job Ref.SectionCivil & Geotechnical EngineeringSheet no./rev. 1Calc. byDr. C. SachpazisDate18/01/2014Chk'd byDateApp'd byDatePASS - Span to depth ratio is OK

Internal bay B-CEffective span;Depth of reinforcement; Midspan moment; Support moment;Design reinforcementLever arm;Area of reinforcement designed; Minimum area of reinforcement required; Area of reinforcement required;Provide 16 dia bars @ 200 centresArea of reinforcement provided;Check deflectionDesign service stress;Modification factor;Allowable span to depth ratio;Actual span to depth ratio;L = 6800 mm d = 202 mmm = (Nult x L2) / (2 x (V(1 + i) + V(1 + i))2) = 51.442 kNm/m m' = i x m = 51.442 kNm/mK = 0.402 x (pb - 0.4) - 0.18 x (pb - 0.4)2 = 0.176 K = m / (d2 x fcu) = 0.036Compression reinforcement is not requiredz = min((0.5 + V(0.25 - (K / 0.9))), 0.95) x d = 191.9 mm As_des = m / (z x fy / ym) = 617 mm2/m As_min = 0.0013 x h = 325 mm2/m As_req = max(As_des, As_min) = 617 mm2/mAs_prov = n x D2 / (4 x s) = 1005 mm2/mPASS - Span reinforcement is OKfs = 2 x fy x As_req / (3 x As_prov x Pb) = 204 N/mm2 ki = min(0.55+(477N/mm2-fs)/(120x(0.9N/mm2+(m/d2))),2) = 1.601 0.9 x 26 x ki = 37.469 L / d = 33.663PASS - Span to depth ratio is OKHOGGING MOMENTS - INTERNAL STRIP Penultimate column B3Consider the reinforcement concentrated in half width strip over the supportDepth of reinforcement;d' = 200 mmSupport moment;m' = 2 x i x m = 149.646 kNm/mLever arm;K = 0.402 x (Pb - 0.4) - 0.18 x (Pb - 0.4)2 = 0.176K = m' / (d'2 x fcu) = 0.107Compression reinforcement is not required z = min((0.5 + V(0.25 - (K / 0.9))), 0.95) x d' = 172.5 mm Area of reinforcement required;As_des = m' / (z x fy / ym) = 1996 mm2/mMinimum area of reinforcement required;As_min = 0.0013 x h = 325 mm2/mArea of reinforcement required;As_req = max(As_des, As_min) = 1996 mm2/mProvide 20 dia bars @ 150 centresArea of reinforcement provided;As prov n x D2 / (4 x s) = 2094 mm2/mPASS - Support reinforcement is OK

GEODOMISI Ltd. - Dr. Costas SachpazisCivil & Geotechnical Engineering Consulting Company for Structural Engineering, Soil Mechanics, Rock Mechanics, Foundation Engineering & Retaining Structures.Tel.: (+30) 210 5238127, 210 5711263 - Fax. : + 30 210 5711461 - Mobile: (+30) 6936425722 & (+44) 7585939944, castas@sachpazis.infaProject: Flat Slab Analysis & Design, In accordance with BS8110:PART 1:1997Job Ref.SectionCivil & Geotechnical EngineeringSheet no./rev. 1Calc. byDr. C. SachpazisDate18/01/2014Chk'd byDateApp'd byDateInternal column C3Consider the reinforcement concentrated in half width strip over the supportDepth of reinforcement;d' = 200 mmSupport moment;m' = 2 x i x m = 102.884 kNm/mLever arm;K = 0.402 x (pb - 0.4) - 0.18 x (pb - 0.4)2 = 0.176K = m' / (d'2 x fcu) = 0.073Compression reinforcement is not required z = min((0.5 + V(0.25 - (K / 0.9))), 0.95) x d' = 182.1 mm Area of reinforcement required;As_des = m' / (z x fy / ym) = 1300 mm2/mMinimum area of reinforcement required;As_min = 0.0013 x h = 325 mm2/mArea of reinforcement required;As_req = max(As_des, As_min) = 1300 mm2/mProvide 20 dia bars @ 200 centresArea of reinforcement provided;As prov n x D2 / (4 x s) = 1571 mm2/mPASS - Support reinforcement is OKHOGGING MOMENTS - EXTERNAL STRIP Penultimate column B1, B2Consider one and a half bays of negative moment being resisted over the edge and penultimate column Width of span;B = 7200 mmEdge distance;e = 125 mmDepth of reinforcement;d' = 200 mmSupport moment;m' = m x i x(e + B + B / 2) / ((0.5 x B) + (0.2 x B) + e) = 158.265kNm/mLever arm;K = 0.402 x (pb - 0.4) - 0.18 x (pb - 0.4)2 = 0.176K = m' / (d'2 x fcu) = 0.113Compression reinforcement is not required z = min((0.5 + V(0.25 - (K / 0.9))), 0.95) x d' = 170.5 mm Area of reinforcement required;As_des = m' / (z x fy / ym) = 2134 mm2/mMinimum area of reinforcement required;As_min = 0.0013 x h = 325 mm2/mArea of reinforcement required;As_req = max(As_des, As_min) = 2134 mm2/mProvide 20 dia bars @ 125 centresArea of reinforcement provided;As prov n x D2 / (4 x s) = 2513 mm2/mPASS - Support reinforcement is OKInternal column C1, C2Consider one and a half bays of negative moment being resisted over the edge and penultimate column Width of span;B = 7200 mmEdge distance;e = 125 mmDepth of reinforcement;d' = 200 mmSupport moment;m' = m x i x(e + B + B / 2) / ((0.5 x B) + (0.2 x B) + e) = 108.810kNm/m

GEODOMISI Ltd. - Dr. Costas SachpazisCivil & Geotechnical Engineering Consulting Company for Structural Engineering, Soil Mechanics, Rock Mechanics, Foundation Engineering & Retaining Structures.Tel.: (+30) 210 5238127, 210 5711263 - Fax. : + 30 210 5711461 - Mobile: (+30) 6936425722 & (+44) 7585939944, castas@sachpazis.infaProject: Flat Slab Analysis & Design, In accordance with BS8110:PART 1:1997Job Ref.SectionCivil & Geotechnical EngineeringSheet no./rev. 1Calc. byDr. C. SachpazisDate18/01/2014Chk'd byDateApp'd byDateK = 0.402 x (Pb - 0.4) - 0.18 x (Pb - 0.4)2 = 0.176 K = m' / (d'2 x fcu) = 0.078

Lever arm;Area of reinforcement required;Minimum area of reinforcement required; Area of reinforcement required;Provide 20 dia bars @ 200 centresArea of reinforcement provided;Corner column A1Depth of reinforcement;Total load on column;Area of column head;Support moment;Lever arm;Area of reinforcement required;Minimum area of reinforcement required; Area of reinforcement required;Provide 16 dia bars @ 150 centresArea of reinforcement provided;Edge column A2, A3Depth of reinforcement;Total load on column;Area of column head;Support moment;Lever arm;Area of reinforcement required;Minimum area of reinforcement required; Area of reinforcement required;Provide 16 dia bars @ 175 centresArea of reinforcement provided;Compression reinforcement is not requiredz = min((0.5 + V(0.25 - (K / 0.9))), 0.95) x d' = 180.9 mmAs_des = m' / (z x fy / ym) = 1383 mm2/mAs_min = 0.0013 x h = 325 mm2/mAs_req = max(As_des, As_min) = 1383 mm2/mAs_prov = n x D2 /

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