Design properties for concrete and reinforcement materials are selected by user.
Modulus of elasticity, Ec and Shear Modulus is calculated automatically according to the selected material’s design property.
Notation
Ec = modulus of elasticity of concrete, psi
Es = modulus of elasticity of reinforcement, psi
fc' = specified compressive strength of concrete, psi
fy = specified yield strength for nonprestressed reinforcement, psi
εs = strain value of reinforcement
εy = yield strain of reinforcement
wc = density, unit weight, of normal weight concrete, lb/ft3
Concrete Design Properties
Specified compressive strength
The compressive strength of the concrete material used in reinforced concrete elements is shown with fc'. ACI defines a minimum value of fc' for structural concrete, with no limit for the maximum value. Limit values for fc' are shown in ACI Table 19.2.1.1.
Application | Minimum fc', psi |
---|---|
General | 2500 |
Foundations for structures assigned to SDC A. B. or C | 2500 |
Foundations for Residential and Utility use and occupancy classifications with stud bearing wall contruction two stories or less assigned to SDC D, E, or F | 2500 |
Foundations for structures assigned to SDC D, E, or F | 3000 |
Special moment frames | 3000 |
Special structural walls with Grade 100 reinforcement | 5000 |
Modulus of Elasticity
The modulus of elasticity Ec , for concrete is calculated as shown in ACI Equation 19.2.2.1.b.
Nonprestressed Reinforcement Bars Design Properties
For non-prestressed reinforcement bars, the stress value below fy is equal to Es times εs which is the value from the strain diagram at the location of the reinforcement. For strains greater than that corresponding to fy, stress is constant and equals to fy.
The modulus of elasticity, Es, for non-prestressed reinforcement bars is 29,000,000 psi.
Information on sizes and areas of various ASTM standard steel reinforcement is presented below in U.S. Customary and SI-METRIC units.
Bar size, no. | Nominal diameter, in | Nominal area, in2 | Nominal diameter, mm | Nominal area, cm2 |
---|---|---|---|---|
#2 | 0.25 | 0.05 | 6.350 | 0.32 |
#3 | 0.375 | 0.11 | 9.525 | 0.71 |
#4 | 0.500 | 0.20 | 12.700 | 1.27 |
#5 | 0.625 | 0.31 | 15.875 | 1.98 |
#6 | 0.750 | 0.44 | 19.050 | 2.85 |
#7 | 0.875 | 0.60 | 22.225 | 3.88 |
#8 | 1.000 | 0.79 | 25.400 | 5.07 |
#9 | 1.128 | 1.00 | 28.651 | 6.45 |
#10 | 1.270 | 1.27 | 32.258 | 8.17 |
#11 | 1.410 | 1.56 | 35.814 | 10.07 |
#14 | 1.693 | 2.25 | 43.002 | 14.52 |
#18 | 2.257 | 4.00 | 57.328 | 25.81 |
Equivalence Between U.S. Customary Units, SI-METRIC, and MKS-METRIC of specified compressive strength, fc', and specified yield strength for reinforcement fy are shown below
U.S. Customary units stress in pounds per square inch (psi) | SI-metric stress in MPA | mks-metric stress in kgf/cm2 | |
---|---|---|---|
fc' = 3000 psi | fc' = 21 MPa | fc' = 210 kgf/cm2 | Concrete |
fc' = 4000 psi | fc' = 28 MPa | fc' = 280 kgf/cm2 | |
fc' = 5000 psi | fc' = 35 MPa | fc' = 350 kgf/cm2 | |
fc' = 6000 psi | fc' = 40 MPa | fc' = 420 kgf/cm2 | |
fy = 40,000 psi | fy = 280 MPa | fy = 17,600 kgf/cm2 | Reinforcement |
fy = 60,000 psi | fy = 420 MPa | fy = 19,000 kgf/cm2 |
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