Nonlinear dynamic study on existing masonry-infilled concrete frames retrofitted with timber panels

This study investigates the dynamic performance of a timber-based seismic retrofit for existing reinforced concrete (RC) buildings, named RC-TP. The core of the proposed retrofit intervention is the replacement of the existing masonry infills with structural timber panels that are connected to the concrete elements using metal dowel-type fasteners and a timber subframe. The unreinforced frames were designed according to codes in force in the 60 s and 70 s, considering exclusively gravity loads to simulate a condition common to a large part of the built heritage across Europe. The seismic performance of single-storey single-bay frames before and after the application of the RC-TP retrofit was assessed via nonlinear simulations, for which the incremental dynamic analysis method was adopted. The results of the extensive dynamic study show the effectiveness of the RC-TP retrofit in increasing the seismic acceleration resisted by the frames and their base shear capacity and in promoting a more ductile failure mechanism. Some general considerations helpful in guiding the implementation of the retrofit system were also drawn.