In-plane shear behavior of masonry walls strengthened with steel fiber-reinforced concrete overlay

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Masonry load-bearing walls in unreinforced masonry (URM) buildings are the major load-resisting elements. The traditional URM buildings have shown poor performance during earthquakes which may be due to lack of lateral strength to withstand the inertia forces. Various retrofitting techniques have been proposed to improve the in-plane behavior of the existing URM walls. In recent proposed retrofitting techniques, innovative construction materials such as steel fiber-reinforced concrete (SFRC) have been employed in the form of a strengthening surface layer on URM walls. Experimental studies on this retrofitting technique which are mostly carried out on masonry panels indicate that this method is practical and efficient for seismic upgrading of URM walls. Therefore, to evaluate the effects of some parameters such as surface layer thickness, retrofitted face of the wall, wall aspect ratio, URM wall strength, and fiber content of SFRC mix on the in-plane shear behavior of both solid walls and walls with openings strengthened with SFRC overlay, a study is conducted through 3D finite-element modeling using software ABAQUS with appropriate material models. The analysis results indicate that in-plane strength enhancement of the retrofitted wall depends on wall aspect ratio. Furthermore, the surface layer thickness and fiber content of the SFRC mix have significant influence on the ultimate in-plane capacity of the walls retrofitted with SFRC surface layer. In addition, the efficiency of this strengthening technique in walls with opening depends on configuration of the surface layer on the walls. Finally, interaction of the masonry wall and SFRC overlay was evaluated through comparing the retrofitted walls’ in-plane strength with in-plane capacity of masonry and SFRC layer.