Effects of concrete parameters in the lateral stiffness of reinforced concrete squat walls

The basis for the effective stiffness values or expressions and their applicability to nuclear power plant elements is not clearly presented in current seismic standards. This paper studies the effective stiffness of reinforced concrete (RC) squat walls under lateral loads. RC squat walls have height-to-length ratios less than or equal to 2. Prediction of the seismic response and proper capturing of the effective stiffness of squat walls are a challenging task, since these walls exhibit a shear-dominated behavior with strong coupling between shear and flexure responses. Finite-element models of several RC squat walls are developed using the commercial software Abaqus. The main objective of these models is to predict the lateral stiffness of RC squat walls appropriately and to identify the parameters that have main influence in the lateral stiffness of these walls. The results from analytical modeling are compared with the results of experimental tests available in the literature. Available expressions in current seismic standards and in the literature for the calculation of effective stiffness for RC squat walls are also evaluated. Key parameters influencing the effective stiffness are identified during the nonlinear analyses and from existing experimental data.