Experimental investigation and analysis on large-scale squat reinforced concrete shear walls with eccentric openings

Squat Reinforced Concrete (RC) shear walls with a shear span ratio of less than 2 are common structural components in nuclear facilities and structural segments with openings formed by doors and entrances. However, mechanical unknowing of openings impacts strength, stiffness, deformation capacity and failing mode, and the arrangement of the openings has significant effects on seismic behavior and in predicting the bearing capacity of such shear-dominated walls. In this paper, the effect of the eccentric openings and opening area ratios on the seismic performance of the squat RC shear walls are investigated by Quasi-Static Tests (QST) on five large-scale squat shear walls. It is shown from the experimental results that compared with corresponding central opening specimens, the specimens with eccentric openings exhibit similar failure modes while presenting higher energy dissipation capability and lower ductility. It is also shown from the experimental results that for asymmetric specimens, the peak load in the negative direction is higher than that in the positive direction, primarily attributed to the longer wall limbs providing improved diagonal bracing and enhancing load resistance. The stiffness and strength of RC shear walls are significantly decreased with the increase of the area ratio. Furthermore, numerical analysis of the experimental shear walls was conducted to account for the effect of eccentric openings, big opening area ratio, small opening area ratio, horizontal eccentricity, and vertical eccentricity on shear strength. The analysis results show that the characteristic values and the reduction rate of shear strength generally exhibit a linear distribution, indicating a strong linear correlation with the target variable. The reduction rate model for the shear strength of squat RC shear walls with openings has been proposed, demonstrating superior accuracy compared to the existing empirical model.