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32 values, each with its units, its uncertainty, and where it came from.

Material Properties 32

Density of Structural Steel measured

ρsteel=7850 kg/m3\rho_{\mathrm{steel}} = 7850\ \text{kg/m}^{3}

kg/m³Typical density of carbon and low-alloy structural steel at 20 °C, 7850 kg/m³ or 490 lb/ft³, essentially independent of grade.

Density of Aluminium Alloy 6061 measured

ρAl=2700 kg/m3\rho_{\mathrm{Al}} = 2700\ \text{kg/m}^{3}

kg/m³Typical density of 6061 aluminium alloy at 20 °C, 2700 kg/m³ or 169 lb/ft³ — about 35 % of steel for the same volume.

Density of Reinforced Concrete measured

ρRC=2400 kg/m3\rho_{\mathrm{RC}} = 2400\ \text{kg/m}^{3}

kg/m³Typical density of normal-weight reinforced concrete, 2400 kg/m³ or 150 lb/ft³, including ordinary reinforcing steel content.

Density of Softwood Timber measured

ρwood=500 kg/m3\rho_{\mathrm{wood}} = 500\ \text{kg/m}^{3}

kg/m³Representative density of construction softwood such as spruce-pine-fir or Douglas fir at 12 % moisture, roughly 500 kg/m³.

Young's Modulus of Structural Steel measured

Esteel=2×1011 PaE_{\mathrm{steel}} = 2 \times 10^{11}\ \text{Pa}

PaElastic modulus of carbon and low-alloy structural steel at room temperature, 200 GPa or 29 000 ksi, effectively grade-independent.

Young's Modulus of Type 304 Stainless Steel measured

ESS304=1.93×1011 PaE_{\mathrm{SS304}} = 1.93 \times 10^{11}\ \text{Pa}

PaElastic modulus of annealed Type 304 austenitic stainless steel at 20 °C, about 193 GPa or 28 000 ksi — 3 % below carbon steel.

Young's Modulus of Aluminium Alloy 6061 measured

EAl=6.89×1010 PaE_{\mathrm{Al}} = 6.89 \times 10^{10}\ \text{Pa}

PaElastic modulus of 6061 aluminium at room temperature, 68.9 GPa or 10 000 ksi — roughly one third the stiffness of steel.

Young's Modulus of Normal-Weight Concrete measured

Ec=2.5×1010 PaE_{c} = 2.5 \times 10^{10}\ \text{Pa}

PaSecant elastic modulus of 28 MPa (4000 psi) normal-weight concrete, about 25 GPa — computed from strength, not measured directly.

Shear Modulus of Structural Steel measured

Gsteel=7.72×1010 PaG_{\mathrm{steel}} = 7.72 \times 10^{10}\ \text{Pa}

PaShear (rigidity) modulus of structural steel at room temperature, 77.2 GPa or 11 200 ksi — the value used in torsion and shear.

Shear Modulus of Aluminium Alloy measured

GAl=2.6×1010 PaG_{\mathrm{Al}} = 2.6 \times 10^{10}\ \text{Pa}

PaShear modulus of common wrought aluminium alloys at room temperature, about 26 GPa or 3800 ksi — one third of steel's value.

Poisson's Ratio of Steel measured

νsteel=0.3 —\nu_{\mathrm{steel}} = 0.3\ \text{—}

—Poisson's ratio of carbon and alloy steel in the elastic range, 0.30 — the lateral contraction per unit of axial extension.

Poisson's Ratio of Aluminium measured

νAl=0.33 —\nu_{\mathrm{Al}} = 0.33\ \text{—}

—Poisson's ratio of wrought aluminium alloys in the elastic range, about 0.33 — slightly higher than steel's 0.30.

Poisson's Ratio of Concrete measured

νc=0.2 —\nu_{c} = 0.2\ \text{—}

—Poisson's ratio of hardened normal-weight concrete under service compression, typically 0.15–0.25 with 0.20 used in design.

Poisson's Ratio of Rubber measured

νrubber=0.499 —\nu_{\mathrm{rubber}} = 0.499\ \text{—}

—Poisson's ratio of natural and synthetic rubber, about 0.499 — nearly incompressible, the practical limit for isotropic solids.

Yield Strength of ASTM A36 Steel

Fy,A36=248,000,000 PaF_{y,\mathrm{A36}} = 248,000,000\ \text{Pa}

PaSpecified minimum yield strength of ASTM A36 structural steel, 36 ksi or 248 MPa — a floor guaranteed by the mill, not a measurement.

Yield Strength of ASTM A992 Steel

Fy,A992=345,000,000 PaF_{y,\mathrm{A992}} = 345,000,000\ \text{Pa}

PaSpecified minimum yield strength of ASTM A992 wide-flange steel, 50 ksi or 345 MPa — the default grade for W-shapes since 1998.

Yield Strength of 6061-T6 Aluminium measured

Fy,6061-T6=276,000,000 PaF_{y,\mathrm{6061\text{-}T6}} = 276,000,000\ \text{Pa}

PaTypical 0.2 % offset yield strength of 6061-T6 aluminium, 276 MPa or 40 ksi, with an ultimate tensile strength near 310 MPa.

Compressive Strength of Normal-Weight Concrete measured

fc′=28,000,000 Paf'_{c} = 28,000,000\ \text{Pa}

PaTypical specified 28-day cylinder strength of ordinary structural concrete, about 28 MPa (4000 psi), with 20–40 MPa the usual range.

Tensile Strength of a Grade 5 Bolt

Sut,Gr.5=827,000,000 PaS_{ut,\mathrm{Gr.5}} = 827,000,000\ \text{Pa}

PaMinimum ultimate tensile strength of an SAE Grade 5 bolt up to 1 in diameter, 120 ksi or 827 MPa, with 85 ksi proof strength.

Tensile Strength of a Grade 8 Bolt

Sut,Gr.8=1,034,000,000 PaS_{ut,\mathrm{Gr.8}} = 1,034,000,000\ \text{Pa}

PaMinimum ultimate tensile strength of an SAE Grade 8 bolt, 150 ksi or 1034 MPa, with 130 ksi proof — the high-strength shop fastener.

Thermal Expansion Coefficient of Carbon Steel measured

αsteel=0.0000117 1/K\alpha_{\mathrm{steel}} = 0.0000117\ \text{1/K}

1/KLinear thermal expansion coefficient of carbon steel near room temperature, 11.7 µm/(m·K) or 6.5 µin/(in·°F).

Thermal Expansion Coefficient of Type 304 Stainless measured

αSS304=0.0000173 1/K\alpha_{\mathrm{SS304}} = 0.0000173\ \text{1/K}

1/KLinear expansion coefficient of Type 304 austenitic stainless steel, 17.3 µm/(m·K) — about 50 % more than carbon steel.

Thermal Expansion Coefficient of Aluminium measured

αAl=0.0000234 1/K\alpha_{\mathrm{Al}} = 0.0000234\ \text{1/K}

1/KLinear expansion coefficient of aluminium near room temperature, 23.4 µm/(m·K) or 13 µin/(in·°F) — twice that of steel.

Thermal Expansion Coefficient of Copper measured

αCu=0.0000168 1/K\alpha_{\mathrm{Cu}} = 0.0000168\ \text{1/K}

1/KLinear expansion coefficient of copper near room temperature, 16.8 µm/(m·K) or 9.3 µin/(in·°F) — 44 % more than steel.

Thermal Expansion Coefficient of Concrete measured

αc=0.00001 1/K\alpha_{c} = 0.00001\ \text{1/K}

1/KLinear expansion coefficient of normal-weight concrete, roughly 8–12 µm/(m·K) — close enough to steel to make reinforcing work.

Friction Coefficient, Dry Steel on Steel measured

μsteel/steel=0.6 —\mu_{\mathrm{steel/steel}} = 0.6\ \text{—}

—Representative static friction coefficient for clean dry steel on steel, about 0.6 with a legitimate range of 0.4 to 0.8.

Friction Coefficient, Lubricated Steel on Steel measured

μsteel/steel,lub=0.1 —\mu_{\mathrm{steel/steel,lub}} = 0.1\ \text{—}

—Representative friction coefficient for oil-lubricated steel on steel in boundary lubrication, about 0.10 (range 0.05–0.15).

Friction Coefficient, Rubber Tyre on Dry Asphalt measured

μdry=0.8 —\mu_{\mathrm{dry}} = 0.8\ \text{—}

—Representative peak friction coefficient for a passenger tyre on dry asphalt, about 0.8 — competition tyres exceed 1.0.

Friction Coefficient, Rubber Tyre on Wet Asphalt measured

μwet=0.5 —\mu_{\mathrm{wet}} = 0.5\ \text{—}

—Representative friction coefficient for a passenger tyre on wet asphalt, about 0.5, falling to 0.3 or below on worn tyres.

Unit Weight of Loose Sand measured

γsand=15,500 N/m3\gamma_{\mathrm{sand}} = 15,500\ \text{N/m}^{3}

N/m³Typical moist bulk unit weight of loose sand, about 15.5 kN/m³ or 99 lbf/ft³; dense sand runs nearer 19.5 kN/m³.

Unit Weight of Soft Clay measured

γclay=16,000 N/m3\gamma_{\mathrm{clay}} = 16,000\ \text{N/m}^{3}

N/m³Typical saturated unit weight of soft normally consolidated clay, about 16 kN/m³ or 102 lbf/ft³, with 14–18 kN/m³ the usual range.

Specific Gravity of Soil Solids measured

Gs=2.65 —G_{s} = 2.65\ \text{—}

—Specific gravity of the mineral solids in most soils, about 2.65 for quartz sands and 2.70–2.75 for clays — remarkably consistent.