A simplified procedure for Nonlinear Static analysis of masonry infilled RC frames

Abstract

Masonry walls are widely used in existing Reinforced Concrete (RC) structures, either as external infill or as internal partitions. Although their mechanical contribution is usually neglected in structural analysis and design, they significantly affect the seismic response of RC frames. This paper proposes a simplified procedure based on NonLinear Static (NLS) analysis for evaluating the seismic response of masonry infilled RC frames. NonLinear Time History (NLTH) analyses are firstly carried out for understanding the actual seismic response of such frames. To this end, an “equivalent-strut” model available in the scientific literature is considered for simulating the nonlinear response of masonry walls under the cyclic actions induced by seismic shakings. Then, based on the results of such NLTH analyses, the aforementioned simplified NLS procedure is formulated by unveiling a stable correlation between the observed dynamic response and a simple scalar parameter that can be easily determined through two NLS analyses carried out on the infilled frame and the corresponding bare one. A statistical description of the accuracy and reliability of the proposed method is finally proposed.