FAQ

The most frequently asked questions about Simplex Beam.

What beam theory is used?

Simplex uses the Euler-Bernoulli classical beam theory. This method is suitable for situations where deformations are small and bending is the main structural behaviour (as opposed to shear or torsion).

How is cracking taken into account during analysis?

In Simplex beam, the user decides whether cracking should be taken into account during analysis. The option "Consider cracking during analysis" can be found under "Calculation settings" for concrete beams. This will affect the deformations and moment distribution for the beam.

Is there a check for crack width in the code check?

Yes. Crack width is checked for quasi-permanent load combinations. The crack width is checked in accordance to the Eurocode/National annex requirements for the exposure class selected in the project. It is therefore important that the correct exposure class is selected. Currently, the crack width itself cannot be seen, only the ratio between current crack width and allowed crack width.

How is deflection calculated for timber?

The calculations in Simplex Beam are done per load combination. If the loads in the load combination have different longevity (for example permanent and short term), the factor used in calculation will be the one for the load with longest duration. This gives a conservative result. In situations where a more detailed result is required, it is currently recommended to create a separate load combination for each load case, then sum up the deformation results manually.

Are all browsers supported?

Simplex Beam supports all the common browsers. We recommend selecting another browser than Mozilla Firefox, which works but has some limitations regarding the user experience.

How are asymmetric sections calculated?

Sections that have local axes different from the global y and z coordinates have a different type of behaviour than symmetric beams. If they are not restrained from lateral movement, they will deform laterally as well as vertically under a vertical load. In Simplex Beam, deformations are calculated with the assumption that the section main axes are parallell to the global axes. In the code check, we account for moments both in local 1 and 2 axes, which are components of the global moment. Under the Properties tab, the user can set the factor for lateral buckling and lateral torsional buckling.

How does concrete fire design work?

The concrete fire design is based on the method described in the Danish national annex. A temperature distribution is calculated based on the cross-section and fire duration. This results in a reduction of the cross-section, reinforcement strength and concrete strength. The design calculations are then carried out as normal for the reduced cross-section. Read more about this in the Pre-Stress Theory Handbook which can be found online.

Is it possible to do fire design for U-profiles?

No, you cannot calculate fire for U-profiles or other non-double-symmetrical cross-sections (same as in FEM-Design).

When doing fire design, is plaster calculated around profiles as a box, or tightly around web, top and bottom flanges?

When using fire plaster it is counted as a box. When using paint it is counted along the surface. It is not possible to change this setting regarding box/along the surface. We assumed that there was no need to change it.