Open Access Editorial

The Open Construction & Building Technology Journal is presently publishing a Special Issue on Infilled Framed Structures focusing on the Experimental & Modelling Aspects. It has been established that masonry infill walls affect the strength, stiffness and ductility of infilled frame structures. However, when designing such structures, it has become common practice not to include the existing infill walls in the structural analysis model as these elements are considered to be essentially non-load bearing. In doing so, the stiffness and strength contribution of the latter elements as well as their interaction with the members of the surrounding frame are ignored. Based on the available, published, experimental and numerical data, it becomes clear that the infill walls have a significant effect on the overall structural performance of the frames. Moreover, based on the above data it has been established that the infill walls usually act as diagonal compression ‘struts’ in the plane of the frame, resulting in an increase of the overall stiffness of the structure and in a reduction of its natural period, which in turn affects the distribution and intensity of the inertia loads generated during seismic excitation, as well as the distribution of the internal actions developing within the structural elements. Although the introduction of infill walls usually results in an overall increase of the seismic capacity and stiffness of the in-filled frame, it may also cause the development of stress concentrations in certain regions of the structure (e.g. the end regions of elements) leading to localized cracking or even unexpected forms of failure, which may potentially have a detrimental effect on the overall response of the frame.