A flexural-shear beam model for interaction analysis of frame-wall systems

In the reinforced concrete frame constructions, the infilled frame structures may have initial gaps between the frame and the infill, which can significantly affect the overall mechanical behavior. Therefore, an adequate description of the contact effects developing at the panel-frame interface is very important to obtain a realistic response of the model. In this paper a simple model of infilled frames is presented in order to evaluate the deformation capacities of framed-masonry shear wall systems, with focus on the interface modeling. The frame and wall are modeled respectively as a flexural beam and a shear beam. A monotonically increasing horizontal force acts at the top of the portal frame. Contact and separation effects, with opening and closing of the interface gap, are taken into account by using interface onedimensional elements, placed in uniform way along the wall height. In particular, the link elements are unilateral, acting only in compression, and obey to a nonlinear constitutive law, in according to which the links can work as elastic links (modeling an elastic contact) or as rigid links (modeling a rigid contact), or not work at all (indicating a no-contact phase). The results, obtained by a semi-analytical approach, are shown in terms of a force-displacement law and contact length-displacement.