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Verification according to AISC 360-22 (LRFD, ASD)

Check of shear

Shear stress resistance for composite cross section with concreted steel cross section is determined conservatively as shear capacity of steel profile.

Nominal shear strength for round cross section filled with concrete is provided by:

where:

Av

-

shear area of steel profile when for a round section is equal to 2As / π

Fy

-

specified minimum yield stress

Kc

-

conservatively considered as 1.0

Ac

-

area of concrete

fc'

-

specified compressive strength of concrete

Check for shear force is determined as:

  • for LRFD: Q / (Vn ϕv ) ≤ 1.0
  • for ASD: Q / (Vn / Ωv ) ≤ 1.0

Check for compressive

Nominal compressive strength for concreted steel cross section is provided by:

Nominal compressive strength of "non-compact" round HSS filled with concrete is provided by:

where:

As

-

area of structural steel section

Ac

-

area of concrete

Nominal compressive strength of "compact" round HSS filled with concrete is provided by:

where:

λp, λr

-

are width-to-thickness ratios due to AISC 360 and Tab.I1.1a

λ

-

width-to-thickness ratio = D / t

D

-

outside diameter of round HSS

t

-

thickness of round HSS

Nominal compressive strength of "slender" round HSS filled with concrete is provided by:

where:

Fn

-

critical buckling stress

where:

Es

-

modulus of elasticity of steel

Available compressive strength is determined as:

  • for LRFD: Pc = Pn ϕc
  • for ASD: Pc = Pn / Ωc

Check for flexure

Nominal flexural strength is determined from the interaction diagram for corresponding distribution of normal stress calculated with influence of bending moment.

For composite cross sections with concreted steel cross section the following normal stress distribution is assumed:

Nominal flexural strength is provided as:

where:

Mp

-

moment corresponding to plastic stress distribution over the composite cross section

For round HSS cross sections filled with concrete the following normal stress distribution depending on D/t ratio is assumed:

Nominal flexural strength of "compact" round HSS filled with concrete is provided by:

Nominal flexural strength of "non-compact" round HSS filled with concrete is provided by:

where:

My

-

yield moment corresponding to elastic-plastic stress distribution over the cross section

λp, λr

-

width-to-thickness ratios determined from Table I1.1b

Nominal flexural strength of slender" round HSS filled with concrete is provided by:

where:

Mcr

-

first yield moment corresponding to elastic stress distribution over the cross section

Available flexural strength is determined as:

  • for LRFD: Mcx = Mn ϕb
  • for ASD: Mcx = Mn / Ωb

Check for axial force and flexure

Check for axial force and flexure is provided by formula:

  • if: N / Pc ≥ 0.2

  • if: N / Pc < 0.2

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