Structural fire protection

Lenz Weber Engineers has in-depth experience with the computer-aided simulation/analysis of the characteristics of building components during a fire, as well as with fire protection engineering methods.

Together with leading engineering firms and research institutes, we are a founding member of a network specialized in the computer-aided analysis of the characteristics of load-bearing structures i.e. building components during a fire.

The introduction of European fire standards (EC1-EC6 and EC9 Parts 1-2) also laid the foundation for analyzing load-bearing structures and/or individual building components during a fire in Germany. The EC 1 1-2 contains parameter-dependent fire stresses (fire scenarios, cellulosic fires)

European standardization has thus also paved the way for the building authorities in Germany to approve engineering methods which link structural with preventative fire protection. Computer-aided simulations allow wide-span steel roofing systems, industrial buildings and venues for events to be built from steel without heat-retardant coating. Wooden buildings can also be analyzed.

We always cross-check our analyses/simulations with the latest international research results and collaborate closely with the corresponding fire safety experts – especially when we are dealing with special-purpose buildings.

What is a hot measurement in structural fire protection?

If a building component is unable to fulfil the prescribed fire protection requirements due to a lack of fire protection cladding, impracticality in the application of the fire protection cladding, change of use or a variety of other reasons, then a hot design is often the most economical solution. Based on the current standards, a calculation is carried out to determine the fire resistance of the component. As the calculated fire resistance is often better than the prescribed requirements, this can solve many problems.

At Lenz Weber we perform most of our hot measurement calculations using software, that can dynamically calculate both the temperature in the section over the entire fire duration, and then – if required – also run a dynamic analysis of the response of the structure over the same period. Although we have a range of other methods that we can use to solve virtually all foreseeable fire protection related problems.

Are there alternatives to a hot measurement?

A hot measurement is not always the most economical solution or there are situations when the calculation will not give the required fire resistance duration. At Lenz Weber we also have many years of experience in prescriptive fire protection and therefore we can also advise you on alternatives, for example: organisational methods, fire protection products with the appropriate European permissions or other alternatives.

We also have an experienced building physics department so that we can offer solutions that do not compromise thermal insulation, thermal bridges, sound insulation, etc.

Brandschutztechnische Verkleidung einer Stahlstütze in einem denkmalgeschützten Gebäude.

How much does a hot measurement cost?

The cost of a hot measurement varies considerably and is best discussed with us directly. In previous projects we have saved costs that otherwise would have made a project unviable. For example, we have saved clients the costs for repairing a damaged intumescent coating , building a new temporary school, fire protection of hundreds of exposed steel sections, building a new sports hall for a school, simplified the smoke extraction system in a cinema,  allowed a theatre in a Denkmalschutz Gebäude. In all of these cases the costs of alternative measures would have been over €100k and would have led to the project been cancelled or considerably reduced the budget for other parts of the project, the Heißbemessung had only costed a fraction of the alternative measures and allowed these projects to successfully continue.

What software is used for hot measurement calculations?

We have experience in software calculations using FRILO, mb AEC, Dlubal, ANSYS and Infograph, however we are very grateful to have a partnership with the software produced by John Hopkins University and Université de Liège: SAFIR.

SAFIR can perform dynamic structural analyses in 1D, 2D and 3D. Thermal analyses in 2d and 3D structures as well as shell elements. Until now SAFIR has been able to solve everything we have asked of it.

We have also collaborated with SAFIR to run a university Masters thesis project on the local buckling of steel sections in fire conditions.

For the CFD flow analysis in fire conditions we use the industry standard of FDS. This software can model any fire situation we can imagine, is verified and has strong heritage. Furthermore, FDS and SAFIR have collaborated together to allow the results from FDS to be directly imported into SAFIR with much greater accuracy and resolution using the RADF interface.

Sometimes none of the above software are appropriate as they are either unnecessarily complicated and simple hand calculation will suffice or there is not yet a software solution available, in this case we are able to go back to basics and calculate by hand.

Contact partner:

For any questions to structural fire protection, please contact Dr. Robin Amy.

Pages with additional information to structural fire protection:

Fire design of concrete – Concrete generally performs well in fire, but there are some exceptions.

Fire design of steel structures – Steel presents additional challenges when making  a hot calculation, but these can be overcome.