Experimental study and efficient shear-flexure interaction model of reinforced concrete shear walls with UHPC boundary columns

Traditional reinforced concrete (RC) shear walls have insufficient deformation capacity under strong earthquake conditions and are difficult to repair due to severe post-earthquake damage. Ultra-high performance concrete (UHPC) is a cement-based composite material with high strength and toughness, which can be applied to shear walls. Therefore, a new type of RC shear walls with UHPC boundary columns was proposed. A rectangular-shaped shear wall and two shear walls with barbell-shaped sections were tested under axial force and lateral cyclic load, and the effects of UHPC distribution, sectional shape and stirrup strength were studied. The hysteresis characteristics, ductility behavior, energy dissipation and stiffness degradation of all the specimens were analyzed and discussed. The test showed that the shear wall with UHPC boundary columns had good crack-width control ability and the damage degree was greatly alleviated even under large axial forces. The addition of UHPC could enhance the ductility and energy dissipation capacity of shear walls, especially for rectangular-shaped walls. Besides, an efficient shear-flexure interaction (SFI) model was developed for the shear walls and it could accurately capture the lateral load versus lateral displacement relationship and crack orientations. This nonlinear analysis model had fast calculation speed and effective results, with a prediction error of less than 5% for peak loads.