Experimental Assessment of the Influence of Drywall Infills on the Seismic Behaviour of RC Frame Buildings

The use of drywall as a non-structural infill has grown significantly due to its rapid and economical installation. Despite this widespread use, a common assumption in structural design is that these elements do not significantly affect seismic performance and are often ignored in analysis. This assumption, however, is increasingly questioned. This study presents a full-scale experimental evaluation of the influence of drywall infill on the seismic response of reinforced concrete frames under cyclic loading. The results quantify how the inclusion of these non-structural elements alters the dynamic properties and structural response of the frame. The infill increased the initial lateral stiffness by approximately three times with respect to the bare frame, thus modifying the structure’s fundamental period. The infill also altered the failure mechanism, initiating with a transient compression strut action at very low drifts, which rapidly and concurrently transitioned into a dominant membrane behavior. This membrane contribution ceased abruptly at a drift of 0.89%, prior to the life-safety limits specified by Eurocode 8. The study’s findings demonstrate the necessity of incorporating the non-linear stiffness and energy dissipation of drywall into structural models to ensure reliable and accurate predictions in seismic design methodologies.