Abstract :
RC frames with unreinforced masonry infill walls are a common form of construction all around the
world. Often, engineers do not consider masonry infill walls in the design process because the final distribution
of these elements may be unknown to them, or because masonry walls are regarded as non-structural elements.
Separation between masonry walls and frames is often not provided and, as a consequence, walls and frames
interact during strong ground motion. This leads to structural response deviating radically from what is
expected in the design. The presence of masonry infills can result in higher stiffness and strength and it is cheap
and built with low cost labor. Under lateral load, Masonry walls act as diagonal struts subjected to
compression, while reinforced concrete confining members (Frames) act in tension and/or compression,
depending on the direction of lateral earthquake forces. The main objective of this research is to develop a
realistic matrix for the response modification factors for medium-rise skeletal buildings with masonry infills. In
this study, the contribution of the masonry infill walls to the lateral behavior of reinforced concrete buildings
was investigated. For this purpose, a five, seven and ten stories buildings are modelled as bare and infilled
frames. The parameters investigated were infill ratio, panel aspect ratio, unidirectional eccentricity,
bidirectional eccentricities. A Parametric study was developed on the behavior of medium rise infilled frame
buildings under lateral loads to investigate the effect of these parameters as well as infill properties on this
behavior.
