Nonlinear Numerical Study of Infilled RC Frames with Openings and Wall-Posts

Abstract

Masonry infill walls, although commonly treated as non-structural elements in reinforced concrete (RC) buildings, have a significant influence on the lateral response of RC frames. This study investigates the effects of masonry infills, opening configurations, and wall-post systems on the nonlinear lateral behavior of RC moment-resisting frames under quasi-static loading using advanced numerical modeling. Three-dimensional finite element models were developed in ABAQUS and validated against reliable experimental results. The numerical program includes bare frames, fully infilled frames, infilled frames with various opening sizes, and wall-post–strengthened configurations, all subjected to displacement-controlled quasi-static lateral loading up to large deformation levels. The results indicate that masonry infills considerably increase the initial stiffness and lateral strength of RC frames, while simultaneously increasing the potential for brittle behavior and stress concentration in the columns. The presence of openings reduces stiffness and disrupts the load transfer mechanism, leading to localized damage concentration around opening corners. In contrast, wall-post systems effectively mitigate these adverse effects by redistributing stresses, improving damage uniformity, and enhancing post-peak stability. The combined use of wall-posts and infilled walls with openings provides a more controlled lateral response in terms of strength, stiffness, and ductility, highlighting wall-posts as an efficient solution for improving the structural performance of infilled RC frames under lateral loading conditions.