Structural & Mechanical

Combined Structural Stress Calculator

Estimate axial, biaxial bending, shear, torsional and von Mises stress for an idealised member, bracket or shaft critical section.

A bracket arm carries a known load at a known distance. What stress occurs, and what section size should I start with?
Preliminary screeningUse this result to screen and frame the problem—not to approve regulated or high-consequence work.
Core formulae

Combined structural stress reference

Axial stressσ_a = N / A
Bending stressσ_b = M_v / Z_v + M_h / Z_h
Torsional shearτ_t = T r / J
Direct shearτ_v ≈ V / A or section screening model
von Misesσ_vm = √(σ² + 3τ²)

For a solid rectangle or plate, vertical depth means the dimension resisting bending in the vertical plane. If the plate bends out of plane, this depth is usually the plate thickness.

Simple arrangement sketch

Bracket-type critical section

Fcritical sectionML
1

Tell us how the structure is loaded

Use guided mode for one real-world force, or enter the actions already known at the critical section.

Actions used at the critical sectionN 0 kN · Vᵥ 15 kN · Vₕ 0 kNMᵥ 12 kN·m · Mₕ 0 kN·m · T 0 kN·m
2

Describe the member cross-section

Width is horizontal. Depth is vertical. The calculator automatically uses the correct section modulus for each bending direction.

Calculated section properties — RHS / SHSArea 3,456 mm² · Zᵥ 179.39 cm³ · Zₕ 119.81 cm³Torsion model: thin-wall closed-section screening. Hollow-section geometry ignores real corner radii.
3

Optional preliminary sizing target

Use a chosen fraction of yield strength to find an idealised starting size. This is not an AS 3990 or AS 4100 design capacity.

Equivalent stress target150 MPa60% of the entered 250 MPa yield strength.
Results

Combined stress at the idealised critical section

Maximum von Mises stress67.31 MPa
Maximum shear stress33.73 MPa

Plane-stress maximum shear from the combined normal and shear screen.

Maximum bending stress66.89 MPa
Governing normal stress66.89 MPa

Axial plus the worst section corner from biaxial bending.

Torsional shear stress0 MPa

thin-wall closed-section screening

Transverse shear stress4.34 MPa

average screening

Axial stress0 MPa
Yield-strength comparison26.9 %

Arithmetic comparison only—not a design utilisation.

Principal stress σ₁67.17 MPa
Principal stress σ₂-0.28 MPa
Below the entered yield strength in this idealised elastic screen

The calculated von Mises stress is 26.9% of the entered yield strength. This does not check code capacity, stability, fatigue or local effects.

Preliminary size helper

Minimum idealised wall thickness: 2.53 mm to reach approximately 150 MPa under the same idealised load model.

This varies only one dimension: vertical depth for a solid rectangle, wall thickness for RHS/CHS, or diameter for a solid round.

What this calculator combines

Axial stress N/A, biaxial elastic bending M/Z, transverse shear screening, supported torsional shear, principal stresses and a plane-stress von Mises equivalent.

Important stress-envelope limitation

The result is a screening envelope, not a point-by-point stress field. Bending, direct shear and torsional maxima may occur at different places on the real section. Hollow-section transverse shear is shown as an average screening value, so local web or wall shear still needs a section-specific check.

What it does not check

Stress concentrations, holes, weld toes, local plate bending, bearing, contact, buckling, lateral-torsional buckling, connection flexibility, second-order effects, plasticity, fatigue, vibration, impact, dynamic amplification, load combinations, code factors or the actual support stiffness.

Job-file record

Save the calculation, not just the number.

Copy a permalink that reloads these inputs, or download a PDF record with inputs, visible results, assumptions, a sensitivity note, date and disclaimer.

Important boundary

A calculator can show the arithmetic. It cannot establish every requirement that applies.

Confirm the actual equipment, loading, materials, condition, jurisdiction, contractual requirements, standard edition and current project documentation before using the result for design, repair, testing or lifting decisions.

Ask an engineer about this calculation →