View Allowable Stress, Minimum Yield and Modulus of Elasticity for Aluminum, Bronze, Stainless Steel and Steel.
Material
Allowable Stress
(psi)
Minimum Yield
(psi)
Modulus of Elasticity
(psi)
Aluminum, 6061-T6
21,000
35,000
10,000,000
Aluminum, 6061-T6 (pipe)
24,000
35,000
10,000,000
Aluminum, 6063-T52
9,500
16,000
10,000,000
Aluminum, 6063-T52 (pipe)
11,500
16,000
10,000,000
Aluminum, 6063-T6
15,000
25,000
10,000,000
Aluminum, 6063-T6 (pipe)
18,000
25,000
10,000,000
Bronze, Alloy C38500
11,000
19,000
17,000,000
Red Brass, Alloy C23000 (pipe)
11,000
18,000
17,000,000
Stainless Steel, Type 304 (tubing)
30,000
55,000
28,000,000
Carbon Steel, C1010
20,000
28,000
29,000,000
Calculations for Structural Design:Basic Equation: When calculating bending stresses, the basis of reasoning is that the bending moment (M) applied to a post or rail must be equaled by the resisting moment. The latter is determined by the unit stress (f) of the railing material and the properties of the railing section — the section modulus (S).
Allowable Stress: The unit stress of a metal is determined by its composition and temper. In structural design, allowable design stress (fs), as used here, are based on a safety factor of 1.65, applied to minimum yield strength, which is generally accepted by the engineering profession. For aluminum round tube and pipe, the allowable stress is increased by a factor of 1.17.
Section Modulus, Neutral Axis: The section modulus (S) is determined by the size, shape and cross-sectional area of a section. It may differ for each of the two neutral axes. The neutral axis of a symmetrical section is the center line. Otherwise, it is the line which passes through the center of gravity of the section, parallel either to its longest or shorted dimension. The two axes, x and y, are perpendicular to each other. For round and for square sections, the section modulus (S) is the same for either axis. Otherwise it is described as Sx or Sy, depending on which axis is involved.
Moment of Inertia: The moment of Inertia (I) about the x or y axis is the section modulus (S) multiplied by c, the distance of the neutral axis or any section from the extreme fibre, that is from the farthest edge of the section, measured at right angles to the axis.