Learnings

Outcomes

The stage 1 (feasibility) study concluded that GFRP reinforcement is the most suitable FRP solution. BFRP reinforcement is the second most suitable option for progression into detailed analysis and potential pilot implementation due to its combination of corrosion resistance, electrical non-conductivity, commercial availability, lifecycle durability, and alignment with emerging international design standards. 

This project aims to establish a technical basis for the future design of FRP reinforced concrete foundations in the UK through analysis of:

• International FRP design guidance and standards
• Material mechanical properties and durability
• Bond and anchorage behaviour
• Fire resistance considerations
• Constructability and installation requirements
• Health and safety implications
• Lifecycle inspection and maintenance requirements
• Environmental and embodied carbon performance

The feasibility study confirmed that existing UK and international supply chains are capable of supporting future FRP reinforcement trials, with multiple suppliers able to provide certified reinforcement products and prefabricated reinforcement systems. The project also demonstrated that FRP reinforcement has strong potential to reduce long-term maintenance requirements and improve durability performance.

Recommendations for further work

Following successful completion of stage 2, the trial stage (stage 3 onwards) should focus on larger-scale demonstration projects and operational deployment within a selected National Grid site. This stage would support development of standardised design procedure, construction methodologies, asset management procedures, and validate the adoption of FRP reinforcement across suitable substation infrastructure applications.

Lessons Learnt

The feasibility stage highlighted several technical and practical limitations that required refinement of the original project approach and provided important lessons for future FRP reinforcement projects.

One of the main challenges identified was the limited availability of UK-specific design guidance for FRP reinforced concrete structures. While international standards such as fib Bulletin 40, ACI 440, CSA S806, and BS EN 1992-1-1:2023 Annex R provide a strong technical basis, significant time was required to compare design methodologies and understand how these could be adapted for National Grid substation applications. Future projects would benefit from establishing a clear design basis and agreed design assumptions at an earlier stage. The study also identified that FRP reinforcement behaves fundamentally differently from traditional steel reinforcement, particularly regarding stiffness, ductility, and failure mechanisms. Early stages of the project focused heavily on ultimate strength comparisons; however, the literature review demonstrated that serviceability behaviour, including crack width and deflection control, is often the governing design consideration for GFRP reinforced concrete. Future projects should prioritise serviceability assessment earlier within the design development process.

Constructability assessments highlighted the importance of accurate detailing and early supplier engagement, as FRP reinforcement cannot be bent or adjusted on site without risk of damage. Prefabricated reinforcement systems and modular construction approaches may therefore provide significant benefits for future implementation.

Overall, the study demonstrated that successful implementation of FRP reinforcement systems requires early collaboration between designers, suppliers, contractors, and fire specialists to ensure technical, practical, and operational requirements are fully considered from the outset.

Dissemination 
None