Effects of masonry walls on the seismic risk of reinforced concrete frame buildings

The observation of building damage after earthquakes has shown that the contribution to the seismic performance of concrete frame buildings from infill walls is significant and should not be ignored. Despite the added mass and the shortening of the structure's fundamental vibration period that may cause a boost in earthquake-induced inertia forces, the presence of infill walls is often beneficial due to the additional strength and energy-dissipation capacity that they provide. In this study we considered 4-, 6-, 8- and 12-story concrete frame buildings with regular plan and stiffness and mass distributions along the height. For each height we modeled three different frame/wall configurations: bare frame; frame with masonry infills at all stories; and frame with infills at all but ground level. We considered bare frames because it is the scheme routinely used for design, in which masonry walls are deemed non-structural and their contributions neglected. To represent buildings with several combinations of lateral strength and structure ductility requirements, we designed bare frames for different base shear values. We located this suite of buildings with and without infill walls in four Italian cities with different earthquake hazard and compared the probabilistic losses. Copyright © (2006) by Earthquake Engineering Research Institute.