Experimental study on seismic behavior of self-slitting composite shear walls with external O-type dampers

Shear walls are efficient lateral load resisting systems for high-rise buildings due to their significant stiffness and load-carrying capacity. The constraints such as floor height can lead to the design of squat walls with brittle failure characteristics. Earthquake damage assessments highlight the need for improved elastic-plastic deformation and energy dissipation capacities to enhance structural safety. To address these needs, this study proposes an innovative self-slitting composite shear wall (CSW) incorporating four circular concrete-filled steel tubular (CFST) columns, plain concrete regions, and external O-type dampers. Experimental program and results are described on four CSWs under quasi-static cyclic loads with varying parameters, such as plain concrete spacing, the number of O-type dampers, and axial load ratios. The results indicate that increasing the number of O-type dampers considerably improves the strength, ductility, and energy dissipation capacity of CSWs. The flexural strength of CSWs is shown to decrease with an increase in the plain concrete spacing. Increasing the axial load ratio enhances the stiffness, delays cracking but diminishes the ductility and energy dissipation of CSWs. The observed failure process of CSWs under lateral loads was characterized by initially forming macroscopic cracks in plain concrete regions, followed by transitions through three distinct phases: integral, slit, and segmented walls. This behavior aligns with the three-level seismic design criteria: enhancing structural resilience by effectively resisting minor earthquakes, accommodating moderate ones, and safely dissipating energy during severe seismic events.