This calculator allows the user to obtain key properties and assess the structural integrity of standard steel sections to ensure compliance with the Australian Standard AS4100:2020. The calculation will identify the design capacities of steel sections to meet axial and flexural design requirements to Ultimate Limit State (ULS) methods.

UB = Universal Beam, UC = Universal Column, WB = Welded Beam, WC = Welded Column, CHS = Circular Hollow Section, RHS = Rectangular Hollow Section, SHS = Square Hollow Section, EA = Equal Angle

Design bending moment in x, M*x

:20

Design bending moment in y, M*y

:10.0

Design shear in x, V*x

:50.0kN

Design shear in y, V*y

:50.0kN

Design axial force, N* (1)

:45.0kNPositive N* is compression, negative N* is tension

Compression properties:

Effective length (compression buckling), Le,x

:5000mm

Effective length (compression buckling), Le,y

:5000mm

Nominal column slenderness, λn,x

:82.799

Nominal column slenderness, λn,y

:229.58

Compression member factor, αa,x

:19.05

Compression member factor, αa,y

:8.85****

Compression member section constant, αb

:0

Modified column slenderness, λ,x

:82.799

Modified column slenderness, λ,y

:229.58

Flexural properties:

Effective length (lateral-torsional buckling), Le

:5000mm

Reference buckling moment, Mo (kNm)

:42.06

Section compression capacity, Ns

:1615kNMajor axis

Slenderness reduction factor, αc,x

:0.66

Member compression capacity, φNc,x

:961kN

N* < φNc,x

:PASS

Minor axis

Slenderness reduction factor, αc,y

:0.14

Member compression capacity, φNc,y

:198.49kN

N* < φNc,y

:PASSMajor axis

Section moment capacity, Ms,x (kNm)

:129.5Minor Axis

Section moment capacity, Ms,y (kNm)

:34.4

Slenderness reduction factor, αs

:0.27

Member moment capacity, φMb (kNm)

:31.73

M*x < φMb

:PASS

Major axis

Combined section capacity, φMr,x (kNm)

:112.94

M*x < φMr,x

:PASS

Minor axis

Combined section capacity, φMr,y (kNm)

:30

M*y < φMr,y

:PASSMajor Axis

Combined in-plane capacity, φMi.x (kNm)

:111.1

M*x < φMi,x

:PASS

Minor Axis

Combined in-plane capacity, φMi,y (kNm)

:23.94

M*y < φMi,y

:PASS

Combined out-of-plane capacity, φMo.x (kNm)

:23.74

M*x < φMo,x

:PASS

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Steel is an alloy of iron and carbon. Iron is present in the earth’s crust as oxidised iron in the form of rock, called “iron ore”, which is what we mine. After mining, iron ore must undergo “reduction”, which means to loose its oxygen so it converts into iron. When iron is combined with carbon, scrap steel and small amounts of other elements, it becomes steel.

Steel is commonly used to construct building frames, including columns, beams and trusses. These elements provide the necessary structural support for the building. Steel's high strength-to-weight ratio, durability and ductility make it an ideal material for various applications.

Ultimate Limit State (ULS) design for steel includes the following checks against failure phenomena.

- Only 'stocky' compression members fail by yielding, that is, to have a slenderness ratio l/r < 25 approximately.
- The form factor is the ratio of the effective to the gross area of the section. If the local buckling form factor, kf = 1.0 then yielding will occur before local buckling, if kf < 1.0 then local buckling will occur before yielding.

- Flexural buckling can only occur in slender compression members, that is, when l/r >= 25 approximately.
- The theoretical buckling load, Nom, is given by the Euler Equation. The slenderness reduction factor, αc reduces the Euler equation to account for residual stresses and imperfections.

- Effective section modulus, Ze is based on the slenderness classification of a section as either 'slender', 'compact' or 'non-compact'. The classification is used to understand whether the elastic or plastic material limits should be used. Slender sections should use an elastic approach to prevent buckling, whereas a compact section is allowed to develop full plastic capacity. All standard UB and UC sections have been sized such that they not slender.

- The elastic flexural-torsional buckling equation, Mo assumes a perfectly elastic and perfectly straight member with a uniform bending moment. The moment modification factor, αm and the slenderness reduction factor, αs reduces the equation to account for non-uniform bending moment and to account for how restraints impact deformations, respectively.
- Flexural-torsional buckling won't occur in minor-axis bending as it is already bending in the less stiff axis and it won't occur in CHS or SHS sections since Ix and Iy are equal from symmetry.

2,400 kg/m3

2-5MPa

20-50MPa

Brittle

Generally lower

Inherent in cover

Inherent in cover

7,850 kg/m3

500MPa

250MPa

Ductile

Generally higher

Not inherent, needs intumescent paint

Subject to weather and rust

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