fib Bulletin 105: the international standard for fibre reinforced concrete

For anyone working seriously with fibre reinforced concrete, fib Bulletin 105 is an indispensable reference work. This report from the international concrete federation fib brings together the current state of knowledge on fibre reinforced concrete and fills an important gap left by Model Code 2020. This article discusses its content and significance.

What is fib Bulletin 105?

fib Bulletin 105 was published at the end of 2022 by the International Federation for Structural Concrete (fib). The report contains state-of-the-art knowledge on Fibre Reinforced Concrete (FRC) — not limited to steel fibre concrete, but covering multiple fibre types.

Fibre reinforced concrete is characterised in the report by its post-cracking behaviour: because fibres bridge crack surfaces, the concrete retains tensile strength after cracking, unlike unreinforced concrete, which loses its tensile strength immediately upon cracking.

Why was this report needed?

Prior to fib Bulletin 105, there was no comprehensive, internationally recognised reference work specifically aimed at designing with fibre reinforced concrete. Model Code 2020 does address the subject, but not with the depth that practice now demands, now that fibre reinforced concrete is increasingly used in structural applications.

What does the report cover?

fib Bulletin 105 covers, among other things:

• The influence of fibre properties on the mechanical performance of the concrete.

• Test methods for determining the mechanical properties of fibre concrete.

• Design in both the serviceability limit state (SLS) and the ultimate limit state (ULS), the two main categories against which structural concrete is assessed.

• Service life aspects, fire safety and mix design.

• Application possibilities for strengthening existing structures and for earthquake resistance.

• Design examples, ranging from analytical calculations to advanced non-linear finite element analyses (NLFEA).

• Practical examples of Ultra-High Performance Fibre Reinforced Concrete (UHPFRC), in both the civil engineering and building sectors.

Why is this relevant for structural engineers and clients?

For structural engineers who want to apply fibre reinforced concrete in (semi-)structural elements, fib Bulletin 105 offers a recognised, internationally endorsed basis on which to ground design decisions — relevant when seeking approval from supervisory bodies and clients who require substantiation.

For clients, the report signals that fibre reinforced concrete has become a mature, scientifically well-founded technology, no longer a niche application without a normative basis.

A practical example

The report refers, among other things, to applications such as the BetonBallon concept: a three-storey office building in Schijndel, built with fibre reinforced sprayed concrete — an example of how fibre reinforced concrete is now also being applied in building construction, not only in floors and infrastructure.

In conclusion

fib Bulletin 105 marks an important step in the standardisation of fibre reinforced concrete: from a practically proven but normatively under-represented material to a technology with a solid, internationally recognised design basis. For anyone wanting to apply fibre reinforced concrete structurally, this report is an essential reference.