Reinforcing masonry with lamellar carbon fibres (CFRP)

Masonry structures usually bear vertical loads. They often fail under horizontal loads, for example due to earthquakes or explosion events, as the masonry joints widen. This is due to the low combined flexural strength of the brick and mortar.

CFRP straps are an efficient method of enahncing masonry. They can also be retrofitted.

This involves milling vertical slits about 2 cm deep across the entire span and gluing the CFRP straps in place on edge with epoxy resin.

This measure has the effect that the low tensile strength of the masonry is increased by the tensile strength of the CFRP lamella. The breaking moment increases, which improves the resistance to horizontal dynamic loads

Researchers at Fraunhofer EMI have derived a comprehensive understanding of this reinforcement through experiments on the shock tube. The results show that the structural failure is transferred from the masonry joint to the brick. 

The test data also build the basis to derive an engineering model. Using this model, the researchers can now simulate various scenarios, component properties or dimensions and calculate suitable protective measures.

The results provide a contribution for planners and engineers within the design for dynamic loadings. Examples are assessment of existing buildings for earthquake loadings or office buildings on industrial plants with a higher hazard for explosion scenarios.