Cyclic Numerical Modeling of Confined Masonry Walls Using Equivalent Strut Model

Confined masonry walls (CMWs) are generally used as a suitable type of lateral force resisting systems in earthquake prone regions. The RC confining members (tie-beams) in such walls are mainly used to provide integrity and increase the ductility of masonry buildings. Considering the inherent complexities of structural behavior of masonry materials and interaction between tie-beams and walls, modeling and analysis of CMWs is one of the challenging problems in the analysis of buildings under lateral loads. Among the building analysis methods, macro-modeling methods have always been considered by researchers due to their proper accuracy and efficiency. The purpose of this study is to modify and verify a suitable macro-model based on the equivalent strut model (Crisafulli infill model) for the cyclic analysis of CMWs. To this end, first, by comparing the behavior of CMWs with infilled frames and identifying their similarities and differences and using the relationships available in the literature, the specifications and parameters of this model are modified for CMWs (with and without opening) as well as CMWs with interior tie-beams. Then, based on the available experimental results of several CMWs and a 3D confined masonry building, the accuracy of the equivalent strut-based model in estimating the lateral stiffness and shear capacity of the specimens is discussed. The results show that it is possible to predict reasonably the overall response of CMWs by the modified equivalent strut model.