The influence of openings on the seismic behaviour of infilled framed structures

Framed structures are usually infilled with masonry walls. Since the infills included in the frame produce significant increase in both horizontal stiffness and strength their structural contribution should not be ignored, especially in regions of moderate and high seismicity. Simple models to take into account infill walls are available for solid walls, such as the diagonal no tension strut models, while infilled frames with openings have not been sufficiently investigated. In the present study the effect of openings on the lateral stiffness and strength of infilled frames is studied by means of numerical and experimental analyses available in the literature and a simple model to take into account the presence of openings is presented. The proposed model, which takes into account the presence and type of reinforcing elements around the openings, allows the evaluation of the reduction of stiffness and strength of the panel due to openings.