Analytical and numerical modeling of innovative strengthening materials (Fiber Reinforced Polymer and Textile Reinforced Mortar) applied to brittle supports

Fiber Reinforced Polymer (FRP) composites and Textile Reinforced Mortar (TRM) materials represent an effective retrofitting strategy for the rehabilitation of masonry and concrete structures. Typically, debonding of an FRP strip from the substrate is a brittle phenomenon involving the support, with the removal of a thin layer of bricks and mortar, and roughly ruled by an initial linear elastic behaviour followed by marked softening, due to the detachment of the strip from the substrate. Several recent and less recent studies, mainly based on experimentation, sophisticated numerical modelling and theoretical approaches, just focus on this topic. The re-elaboration of the experiences collected on this topic allowed to conceive dedicated technical recommendations, as in Italy with the CNR DT 200 - technical code on FRP reinforcement applied to concrete and masonry.

The debate on the application of FRP composites in general and C-FRP in particular for the rehabilitation and seismic upgrading of historical masonry structures or existing buildings is however still open, some authors raising doubts on the long-term efficacy and cost of the intervention when compared with traditional techniques. The major drawback seems however related to the reversibility issue, which is nowadays considered a priority for any seismic upgrading with innovative materials. In order to be consistent with such conservation requirements, part of the scientific efforts have been recently channeled to alternative – appearing more reversible – innovative strengthening systems, such as Textile Reinforced Mortars TRMs.

In addition to open issues related to the reversibility, durability and vapor permeability of FRP strips, from a strictly structural point of view, the application of FRP on masonry walls and arches is certainly very interesting.

The project focuses on the development of advanced analytical and numerical models of innovative reinforcement materials, such as Fiber Reinforced Polymers (FRP) and Textile Reinforced Mortars (TRM), to improve the adhesion of strengthening composites when applied to masonry.

The project offers a unique opportunity to carry out a high-quality research project. The project will be coupled with experimental laboratory tests to enable the calibration and development of advanced modeling approaches.

References

• State-of-the-art review and future research directions for FRP-to-masonry bond research: Test methods and techniques for extraction of bond-slip behaviour, J. Vaculik, P. Visintin, N.G. Burton, M.C. Griffith, R. Seracino, Construction and Building Materials, Volume 183, 2018
• State-of-the-art on strengthening of masonry structures with textile reinforced mortar (TRM), L. A. S. Kouris, T. C. Triantafillou, Construction and Building Materials, Volume 188, 2018.
• Effectiveness of Textile Reinforced Mortar (TRM) materials for the repair of full-scale timbrel masonry cross vaults, E. Bertolesi, B.Torres, J. M. Adam, P. A. Calderón, J. J. Moragues, Engineering Structures, Volume 220, 2020.

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