Experimental Investigation of Infilled Reinforced Concrete Frames with Openings

The influence of masonry openings on the seismic performance of infilled reinforced concrete frames, designed according to current code provisions, is investigated. Eight 1/3-scale, single-story, single-bay frame specimens were tested under reversed cyclic, quasistatic, horizontal loading up to a drift level of 4%. lit all the examined cases, the shear strength of columns was higher than the cracking shear strength of solid infill. The parameters investigated include the shape and the size of the opening. Assessment of the behavior of the frames was also attempted based on the observed failure modes, strength, stiffness, ductility, energy dissipation capacity, and degradation due to cycling. The experimental results show the significance of various forms of openings on the reduction of strength, stiffness, and energy dissipation capability for all the examined cases of infilled frames. A continuous force-deformation model based on an equivalent strut approach is proposed for masonry infill panels with openings. The model, which is applicable for degrading elements, can be implemented to replicate a wide range of monotonic force-displacement behavior resulting from different design and geometry, by varying the control parameters of the model.