The AISC-ASD 9th Edition specifies the design of steel tube and pipe columns under axial compression by checking against allowable compressive stresses. Key design considerations include cross-section properties, slenderness ratio, effective length, and the column buckling curve defined in the code. This Excel sheet automates these checks for both HSS (Hollow Structural Section) rectangular tubes and circular pipes.
Tube and Pipe Columns in Steel Construction
Hollow structural sections (HSS) — both rectangular (square or rectangular) and round (circular pipes) — are widely used as columns in steel construction because of their:
- Excellent resistance to biaxial bending (equal stiffness in both directions for square and round sections)
- High torsional stiffness
- Aesthetic appeal in exposed structural applications
- Efficient material distribution — the hollow core means material is located where bending stresses are highest
AISC-ASD 9th Edition Column Design Method
For axially loaded columns, AISC-ASD 9th uses the following approach:
- Compute the slenderness ratio KL/r for the governing axis
- Determine Cc (critical slenderness ratio = √(2π²E/Fy))
- For KL/r ≤ Cc: use inelastic buckling formula (parabolic curve)
- For KL/r > Cc: use elastic (Euler) buckling formula
- Compare actual axial stress fa with allowable Fa
Local Buckling Check for HSS
HSS sections must also be checked for local buckling of the wall elements. The AISC-ASD 9th Edition requires that the width-to-thickness ratio b/t (for rectangular HSS) or D/t (for round pipes) does not exceed the compact section limits. Sections exceeding these limits are subject to reduced allowable stresses.
Sheet Outputs
- Governing KL/r ratio
- Allowable axial stress Fa
- Actual axial stress fa
- Unity check (fa/Fa ≤ 1.0)
- Local buckling check for wall elements
Download the AISC-ASD 9th HSS/Pipe Column Design Sheet
This sheet is a practical daily-use tool for steel connection and frame designers working under AISC-ASD 9th. It is widely used for designing pipe columns in industrial structures, mezzanines, and equipment support frames. The transparent allowable stress calculation makes it easy to include in formal connection design packages. Download the free Excel sheet below.
