Theoretical study for predicting the fundamental period of concrete buildings including non-structural elements

Abstract

Abstract This paper presents a theoretical study for estimating the fundamental period of multi-storey buildings with plan symmetry and without horizontal or vertical irregularities, considering a structural system composed of reinforced concrete frames. In this study, non-structural elements (masonry infill walls) are assumed to participate in the distribution of seismic loads. The fundamental period was estimated using simplified expressions obtained through regression analysis of results from modal analyses performed on 288 buildings with geometric and mechanical characteristics representative of Brazilian construction practice. The structural models consisted of frames with equivalent diagonal struts used to simulate the presence of masonry infill walls. The simplified expressions obtained from the regression analyses were compared with the approximate expression recommended by the Brazilian code for the design of seismic-resistant structures. In addition, the seismic base shear values calculated using the investigated expressions were evaluated through the Equivalent Lateral Load Method, revealing relevant differences among the predicted seismic demands.