Seismic retrofit of infilled RC frames with textile reinforced mortars: State-of-the-art review and analytical modelling

Significant damage to existing reinforced concrete (RC) frame structures during recent earthquakes has highlighted the potential detrimental effect of non-structural masonry infills. Several experimental studies have hence investigated the use of composite materials for in-plane retrofitting to reduce the risk of brittle collapse of the infills. In this review, the state-of-the-art on strengthening infilled RC frames with textile-reinforced mortars (TRM), a new class of composite material consisting of open-mesh textiles embedded in a cementitious matrix, is presented, highlighting the great potential of this retrofit solution for large-scale interventions on the existing building stock. A database of experimental results is compiled to evaluate the effect of different parameters on the effectiveness of the retrofitting applications. The stiffness of the fibre material, as well as the angle of application are found to be crucial factors. To ensure adequate analytical modelling for predicting the retrofitted behaviour, a macro-model, using an additional tensile tie to account for the TRM, is first calibrated by means of the experimental data gathered from the literature. Correlation between experimental parameters and the obtained effective strain is then assessed and an empirical formulation of effective strain in terms of fibre stiffness and retrofit amount is finally proposed.