SEISMIC RESPONSE OF A NON-DUCTILE RC FRAME WITH MASONRY INFILLS AND RETROFITTED WITH ECCENTRIC STEEL BRACING

The seismic performance of a non-ductile RC frame with and without masonry infill panels and the assessment of a retrofitting intervention using eccentric steel bracing were investigated through numerical analyses. The main objectives of this study were: a) the development and calibration of numerical models capable of predicting the seismic response of RC frames designed only for gravity loads; b) the evaluation of the masonry infill effects on the global structural response; c) the assessment of the effectiveness of a retrofitting solution for masonry infilled RC frames based on the replacement of infill panels by eccentric steel bracing with vertical shear link. The developed numerical models were calibrated with the results of the experimental tests carried out on RC structures at the JRC ELSA laboratory and satisfactory agreement was obtained. The numerical results showed that the infill panels may protect RC frames for medium intensity seismic input. In case of high levels of seismic action the analyses outlined the brittleness of the infilled frames after reaching the maximum strength, indicating significant stiffness and strength degradation. The retrofitting intervention by eccentric bracing with vertical shear link reduced the displacements, prevented the formation of soft-storey mechanisms and provided a stable energy dissipation uniformly distributed throughout the RC frame.

Keywords:

RC Frames , Retrofitting , Masonry Infills , Steel Bracing , Seismic Analyses