Concrete and Reinforcement Materials per ACI 318-19 with ideCAD
How does ideCAD define concrete and reinforcement materials according to ACI 318-19?
Design properties for concrete and reinforcement materials are selected by the user.
Modulus of elasticity, E_{c}, and Shear Modulus is calculated automatically according to the selected material's design property.
Notation
E_{c } = modulus of elasticity of concrete, psi
E_{s } = modulus of elasticity of reinforcement, psi
f_{c}^{'}_{ } = specified compressive strength of concrete, psi
f_{y } = specified yield strength for nonprestressed reinforcement, psi
ε_{s } = strain value of reinforcement
ε_{y } = yield strain of reinforcement
w_{c} _{ }=_{ }density, unit weight, of normal weight concrete, lb/ft^{3}
Concrete Design Properties
Specified compressive strength
The compressive strength of the concrete material used in reinforced concrete elements is shown with f_{c}^{'}. ACI defines a minimum value of f_{c}^{'} for structural concrete, with no limit for the maximum value. Limit values for f_{c}^{'} are shown in ACI Table 19.2.1.1.
Application | Minimum f_{c}', 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 construction 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 E_{c}, 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 f_{y} is equal to E_{s} times ε_{s} which is the value from the strain diagram at the location of the reinforcement. For strains greater than that corresponding to f_{y}, stress is constant and equals f_{y}.
The modulus of elasticity, E_{s}, for nonprestressed reinforcement bar, 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, in^{2} | Nominal diameter, mm | Nominal area, cm^{2} |
---|---|---|---|---|
#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, f_{c}^{',} and specified yield strength for reinforcement f_{y} are shown below.
U.S. Customary units stress in pounds per square inch (psi) | SI-metric stress in MPA | mks-metric stress in kgf/cm^{2} | |
---|---|---|---|
f_{c}^{'} = 3000 psi | f_{c}^{'} = 21 MPa | f_{c}^{'} = 210 kgf/cm^{2} | Concrete |
f_{c}^{'} = 4000 psi | f_{c}^{'} = 28 MPa | f_{c}^{'} = 280 kgf/cm^{2} | |
f_{c}^{'} = 5000 psi | f_{c}^{'} = 35 MPa | f_{c}^{'} = 350 kgf/cm^{2} | |
f_{c}^{'} = 6000 psi | f_{c}^{'} = 40 MPa | f_{c}^{'} = 420 kgf/cm^{2} | |
f_{y} = 40,000 psi | f_{y} = 280 MPa | f_{y} = 17,600 kgf/cm^{2} | Reinforcement |
f_{y} = 60,000 psi | f_{y} = 420 MPa | f_{y} = 19,000 kgf/cm^{2} |