In-plane behavior of URM wall with openings strengthened with ECC subjected to cyclic load

Abstract

Unreinforced masonry (URM) structures exhibit high vulnerability in the moderate or strong earthquakes. The door- or window-type opening would further increase the seismic vulnerability, in which there is a weak area in the structures with stress concentrations. To improve the seismic behavior of perforated URM wall, a reinforcement of engineered cementitious composites (ECC) overlay was used on the both sides of the wall. Two 1/2-scale H-shaped specimens were prepared and tested under cyclic lateral loads. The damage patterns, hysteretic curves, envelope curves, stiffness degradation and energy dissipation of specimens were analyzed and discussed. The ECC effect can be observed as an increase of lateral resistance (maximum lateral force from 87.5 kN to 255.2 kN), and energy dissipation capacity (the cumulative energy dissipation up to ultimate state from 10.6 kJ to 21.5 kJ). Moreover, ECC overlay was able to control the crack initiation and propagation. The wide cracks along mortar joints observed in the spandrel of control specimen became multiple flexural cracks in the masonry piers after ECC reinforcement. The final failure of strengthened wall was dominated by the bending of piers, which was beneficial to improving the collapse resistance of masonry structures in the strong earthquake excitation.