Fire design of sway frames

How to design fire-exposed sway frames?

The design methods for the constructive fire protection in the Eurocodes apply to braced structures. This is due to the additional stresses as a result of the effect from the second-order theory in sway constructions, which quickly lead to stability problems in the event of a fire. A similar problem often arises for cantilever columns out of reinforced concrete due to their great slenderness.

For this reason, sway frames exposed to fire can currently only be designed with so-called general calculation methods. Even in the case of a braced frame, it is advisable to regard the frame as a whole. For example, the fire-exposed beam expands in the early stages of the fire. This expansion is hindered by its supports, which is given by the adjacent columns. The hindered movement can lead to considerable constraining forces in the beam. In the animation below, you can see an example of the fire design of a steel frame (two-hinged frame) for the fire resistance class R30.

How I design sway frames

For sway frames, a dimensioning with special programs for the fire design is necessary, which covers the non-linear relationships and the effects according to the second order theory consider in case of fire. I prove these frames with a so-called fire design. The scope of the documentation can of course be agreed with you and usually contains information on the heating of the cross-section, the fire resistance period of the frames and its deformations. I am of course happy to provide additional services depending on your task.

What are your advantages?

With the fire design, sway frames can be dimensioned for the event of fire. This enables innovative construction methods, as the additional costs for stiffening can be omitted.

How I advise you.

The easiest way is to give me a call or send me an email. We will then clarify at short notice whether I can support you. This consultation is of course completely free of charge and without obligation.