Advances in macro modeling for seismic performance assessment of infilled reinforced concrete structures

This article presents a comprehensive review of advancements in macro modeling techniques for assessing the seismic performance of reinforced concrete structures with masonry infill walls. The study emphasizes the importance of accurately modeling the contribution of masonry infill walls, which are often treated as non-structural elements in seismic design. However, research has shown that masonry infills significantly enhance the lateral stiffness and strength of reinforced concrete frames, influencing their overall seismic behavior. The paper explores the historical evolution of macro modeling approaches, starting from early single-strut models introduced in the 1960s, to more refined multi-strut and spring-based models developed in recent decades. These advancements allow for better simulation of the non-linear behavior of masonry under lateral loads, including cracking, crushing, and interaction with the surrounding frame. The article also discusses the introduction of fiber hinge models, which offer a more sophisticated method for capturing both flexural and shear deformations in infilled frames. A key aspect of the study is the validation of the nonlinear macro-model through comparisons with experimental data. Three infilled frame specimens-constructed with different masonry types (limestone, hollow clay, and lightweight concrete) were analyzed under vertical and lateral loading. The force-displacement curves from the analytical model closely matched the experimental results, demonstrating the accuracy of the macro-model in predicting the seismic response of infilled frames. Notably, the model accurately captured stiffness degradation and maximum lateral strength, key indicators of seismic performance.