Multi-strut macro-model for masonry infilled frames with openings

This study aims to propose a multi-strut macro-model, capable of simulating the overall force-displacement behaviour of infilled frames with various opening configurations. For this purpose, the results of finite element modelling calibrated against several experimental data are employed to determine the characteristics of a multiple-strut model for such infilled frames. The results indicate that the size of the opening along with its position, compared to the size of the infill wall, can significantly affect both the inclination and also the effective width of the struts and therefore, the overall behaviour of infilled frames with opening. The proposed model is evaluated parametrically against FEM numerical results, with varying characteristics such as opening size and position, opening height-to-length ratio, height-to-length ratio of the infilled frame and relative rigidity of frame to the infill wall. The comparison of the derived results with the analytical and experimental findings demonstrates the ability of the model to approximate the lateral response of infilled frames with openings in a reliable and robust manner. A simple reduction factor for the ultimate strength of the perforated infilled frames is proposed based on opening size relative to infill wall size as well as relative stiffness of the frame and infill wall.