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 Project
Spreadsheets to BS 8110etc
REINFORCED CONCRETE COUNCIL
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 Client
Advisory Group
Made byDatePage
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 LocationGrid line 1RC19-févr.-202633OPERATING INSTRUCTIONS
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Crack Width Calculations to BS8110: 1997/ BS8007:1987
CheckedRevisionJob No ENTER DATA IN BLUE CELLS ONLY.
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Originated from RCC14.xls on CD © 1999 BCA for RCC
chg-R68 RED MESSAGES INDICATE ENTRY ERRORS.
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CRACK WIDTH CALCULATIONS - FLEXURE
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INPUT
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fcu=40N/mm2
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fy=500N/mm2
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Area of reinforcement " As " =
2681mm2
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b =1000mm
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h =250mm
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d =176mm
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Minimum cover to tension reinforcement " CO " =
50mm
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Maxmum bar spacing " S " =
150mm
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Bar dia " DIA " =
16mm86,81
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" acr " =(((S/2)^2+(CO+DIA/2)^2)^(1/2)-DIA/2) as default or enter other value =
86,8mm
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"acr " is distance from the point considered to the surface of the nearest longitudinal bar
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Applied service moment " Ms "=
69,0KNm
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FALSE
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CALCULATIONS
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moduli of elasticity of concrete " Ec" = (1/2)*(20+0.2*fcu) =
14,0KN/mm2BS8110 part 2 cl 3.8.3 and cl 7.2
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moduli of elasticity of steel " Es " =
200,0KN/mm2
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Modular ratio " a " = (Es/Ec) =
14,29
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" r " = As/bd =
0,015Note: " x " is a function of modular ratio and area of reinforcement and is independent of the appliced moment.arwe
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depth to neutral axis, "x" = (-a.r +((a.r)2 + 2.a.r)0.5.d =
84mm
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BS8110 part 2 cl 3.8.3 and BS8007 Appendices B
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" Z " = d-(x/3) =
148
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Reinforcement stress " fs " = Ms/(As*Z) =
174N/mm2
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Concrete stress " fc " = (fs*As)/(0.5*b*x) =
11,10N/mm2BS8110 part 2 cl 3.8.3 and BS8007 Appendices B
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Strain at soffit of concrete beam/slab " e1 " = (fs/Es)*(h-x)/(d-x) =
0,001568
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Strain due to stiffening effect of concrete between cracks " e2 " =
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e2 = b.(h-x)2/(3.Es.As.(d-x)) for crack widths of 0.2 mm
Used
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e2 = 1.5.b.(h-x)2/(3.Es.As.(d-x)) for crack widths of 0.1 mm
n/a
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e2 = 0,000186
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Average strain for calculation of crack width " em "= e1-e2 =
0,001382
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Calculated crack width, " w " = 3.acr.em/(1+2.(acr-c)/(h-x))
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CALCULATED CRACK WIDTH, 'w' =
0,25mm
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