Evaluating the out-of-plane response of masonry infill walls in seismic conditions: a parametric analytical model

Masonry infill walls, often included within reinforced concrete (RC) frames, significantly impact the seismic response of these structures, even though they are typically classified as nonstructural elements. During seismic events, these infill walls can interact with the surrounding RC frame in ways that alter the overall behaviour, sometimes leading to brittle failure mechanisms such as out-of-plane (OOP) collapse. This collapse is particularly concerning, as it can occur under lateral seismic loads, posing safety risks. This study addresses this challenge by presenting an analytical model developed to assess the OOP performance of masonry infill walls under seismic loads. We conduct a parametric analysis, evaluating key factors such as the geometry and mechanical properties of the masonry, the slenderness and aspect ratio of the infill to understand their influence on OOP behaviour. The proposed model integrates vertical and horizontal arching mechanisms, considering the surrounding RC frame's flexibility, which can significantly affect the OOP response of the masonry. Validation against experimental data demonstrates the model’s accuracy and reliability in predicting the OOP behaviour of masonry infill walls. This analytical model provides valuable insights for professionals designing safer RC structures, highlighting its potential applications in improving seismic performance and guiding future design for masonry infills.