Bending analysis
of beams using BendIT©
To calculate different load cases quickly and easily, BendIT is now available directly as an online calculator. Select the profile, dimensions, and load case; the calculation is performed directly in your browser.
The calculated values are non-binding guidance for preliminary sizing only and do not replace a project-specific structural analysis. Despite careful implementation, the calculator may produce incorrect results; all inputs, load assumptions, and results must be reviewed by a qualified professional before use.
Enter the profile type and dimensions, select the load case, and calculate the key values directly.
Profile and Dimensions
For standard profiles, the cross-sectional area A, second moment of area I, and section modulus W are calculated from the dimensions. For exact catalog values, you can switch to manual profile properties.
Results
The calculated values are non-binding guidance for preliminary sizing only and do not replace a project-specific structural analysis. Despite careful implementation, the calculator may produce incorrect results; all inputs, load assumptions, and results must be reviewed by a qualified professional before use.
Calculation of bending
In the bending analysis, the bending stress and deflection of a GRP section under transverse loading are estimated. The decisive factors are the load case, span, modulus of elasticity, and the section’s moment of inertia and section modulus.
Bending stress and deflection
σb =Mb /Wb
f = F ·L3 / (48 · E · I)
- σb = bending stress
- Mb = bending moment
- Wb = section modulus
- E = modulus of elasticity
- I = moment of inertia
Calculation of pressure
When subjected to compressive loading, the compressive stress and buckling resistance of the section are taken into account. The Euler buckling load serves as an idealised estimate for slender members and is not a substitute for a project-specific structural analysis.
Compressive stress and buckling load
σd = F / A
Fkrit =π² · E · I /lk²
- σd = compressive stress
- F = compressive force
- A = cross-sectional area
- Fkrit = critical buckling load according to Euler
- lk = buckling length
- E = modulus of elasticity
- I = moment of inertia
Torsion calculation
In the case of torsional loading, the torsional stress and angle of rotation of a section are estimated as a result of a torque. The decisive factors are the torsional moment, the shear modulus and the section properties relevant to torsion.
Torsional stress and angle of rotation
τ = T /Wt
φ = T · l / (G ·Jp)
- τ = torsional stress
- T = torsional moment
- Wt = moment of resistance to torsion
- φ = angle of rotation
- G = shear modulus
- Jp = polar moment of inertia
Wind load
FRP profiles subjected to wind loads are preliminarily dimensioned on the basis of the dynamic wind pressure and the exposed surface area. The wind speed determines the pressure, and this in turn determines the resulting wind force acting on the profile.
Wind pressure and wind force
q = 0.613 ·v²
Fw = q · A
- q = dynamic wind pressure [N/m²]
- v = wind speed [m/s]
- A = exposed area [m²]
- Fw = resulting wind force [N]
Calculation: Train
In the case of tensile loading, the tensile stress is calculated from the applied force and the effective cross-sectional area. This calculation is intended for rapid preliminary sizing and is not a substitute for a project-specific structural analysis.
Tensile stress
σz = F / A
- σz = tensile stress
- F = tensile force
- A = effective cross-sectional area