Environmentally-induced loss of performance in FRP strengthening systems bonded to full-scale masonry structures

The issue of building materials deterioration due to environmental actions, which are expected to worsen in the future according to climate change predictions, is recognized as high-priority by the scientific community. However, the impact of material deterioration on the structural and seismic performances of masonry and historical structures strengthened with composites has not been investigated in detail, even though potentially significant. This paper aims to evaluate the environmentally-induced loss of performance in fiber reinforced polymer (FRP) strengthening systems bonded to masonry structures. An efficient damaging block-based modelling strategy, recently developed by the authors, is used to model masonry. FRP strips are originally introduced in the model and bonded to masonry blocks through a contact-based formulation with cohesion. This novel numerical approach is validated through FRP-strengthened masonry wall benchmarks. Numerical analyses are performed on FRP-strengthened in- and out-of-plane loaded masonry full-scale walls and houses with non-degraded material properties to predict the structural response at design conditions. Then, degraded material properties are deduced from accelerated ageing laboratory tests which investigated environmental degradation in FRP-strengthened masonry and are adopted in the same numerical analysis framework to predict the structural response at degraded conditions. Therefore, the environmentally-induced loss of performance in FRP strengthening systems bonded to masonry structures is deduced by comparing the structural response at degraded conditions with the one at design conditions.