Lateral Stiffness of Masonry Infilled Reinforced Concrete (RC) Frames with Central Opening

Window and door openings are inevitable parts of infill walls for functional reasons. Currently, publications like FEMA‐273 and ATC‐40 contain provisions for the calculation of stiffness of solid infilled frames mainly by modeling infill as a “diagonal strut.” However, such provisions are not provided for infilled frames with openings. The present study proposes a reduction factor for effective width of diagonal strut over that of the solid reinforced concrete (RC) infilled frame to calculate its initial lateral stiffness when a central window opening is present. The study is based on initial lateral stiffness which is taken at 10% of the lateral strength of the infilled frames.